:icons:
:toc:
:toc-placement: manual
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image::images/Subsurface4Banner.jpg["Banner", align="center"]

[big]#MANUEL UTILISATEUR#

*Auteurs du manuel* : Willem Ferguson, Jacco van Koll, Dirk Hohndel, Reinout Hoornweg,
Linus Torvalds, Miika Turkia, Amit Chaudhuri, Jan Schubert, Salvador Cuñat, Pedro Neves

[blue]#_Version 4.3, Décembre 2014_#


Bienvenue en tant qu'utilisateur de _Subsurface_, un programme avancé
d'enregistrement de plongées (carnet de plongées) avec une bonne
infrastructure pour décrire, organiser, interpréter et imprimer des plongées
en scaphandre et en apnée. _Subsurface_ offre de nombreux avantages par
rapport à d'autres solutions logicielles similaires :

 - Do you need a flexible way of logging dives using recreational equipment,
   even not using a dive computer?
 - Do you use two different dive computer brands, each with its own proprietary
   software for downloading dive logs? Do you dive with rebreathers as well as
   open circuit or recreational equipment? Do you use a Reefnet Sensus
   time-depth recorder in conjunction with a dive computer? _Subsurface_ offers
   a standard interface for downloading dive logs from all these different
   pieces of equipment and to store and analyse the dive logs within a unified
   system.
 - Do you use more than one operating system? _Subsurface_ is fully compatible
   with Mac, Linux and Windows, allowing you to access your dive log on each of
   your operating systems using a single application.
 - Do you use Linux or Mac and your dive computer has only Windows-based
   software for downloading dive information (e.g. Mares)? _Subsurface_
   provides a way of downloading and analysing your dive logs on other
   operating systems.
 - Do you need an intuitive graphical dive planner that integrates with and
   takes into account the dives that have already been logged?

_Subsurface_ binaries are available for Windows PCs (Win XP or later), Intel
based Macs (OS/X) and many Linux distributions. _Subsurface_ can be built
for many more hardware platforms and software environments where Qt and
libdivecomputer are available.

The scope of this document is the use of the _Subsurface_ program. To
install the software, consult the _Downloads_ page on the
http://subsurface-divelog.org/[_Subsurface_ web site].  Please discuss
issues with this program by sending an email to
mailto:subsurface@subsurface-divelog.org[our mailing list] and report bugs
at http://trac.hohndel.org[our bugtracker].  For instructions on how to
build the software and (if needed) its dependencies please consult the
INSTALL file included with the source code.

*Audience*: Recreational Scuba Divers, Free Divers, Tec Divers, Professional
Divers

toc::[]

[[S_UserSurvey]]

Le sondage utilisateur
----------------------
In order to develop _Subsurface_ in a way that serves its users in the best
possible way, it is important to have some user information. Upon launching
_Subsurface_ after using this software for a week or so, a one-box user
survey pops up. It is entirely optional and the user controls what, if any,
data are sent to the _Subsurface_ development team. Any data that the user
chooses to send is extremely useful, and will only be used to steer future
development and to customise the software to fit the needs of the
_Subsurface_ users. If one completes the survey, or clicks the option not to
be asked again, that should be the last communication of this nature one
receives.  However, if one's diving and/or subsurface habits change and one
wishes to provide another survey, this can be done by launching _Subsurface_
with the _--survey_ option on the command line.

[[S_StartUsing]]
Start Using the Program
-----------------------

The _Subsurface_ window is usually divided into four panels with a *Main
Menu* (File Import Log View Filter Help) at the top of the window (for
Windows and Linux) or the top of the screen (for Mac and Ubuntu Unity). The
four panels are:

The *Dive List* to the bottom left containing a list of all the dives in the
user's dive log. A dive can be selected and highlighted on the dive list by
clicking on it. In most situations the up/down keys can be used to switch
between dives. The *Dive List* is an important tool for manipulating a dive
log.

The *Dive Map* to the bottom right, showing the user's dive sites on a world
map and centred on the site of the last dive selected in the *Dive List*.

The *Dive Info* to the top left, giving more detailed information on the
dive selected in the *Dive List*, including some statistics for the selected
dive or for all highlighted dive(s).

The *Dive Profile* to the top right, showing a graphical dive profile of the
selected dive in the *Dive List*.

The dividers between panels can be dragged in order to change the size of
any of the panels. _Subsurface_ remembers the position of the dividers, so
the next time _Subsurface_ starts it uses the positions of the dividers from
when the program was last used.

If a dive is selected in the *Dive List*, the dive location, detailed
information and profile of the _selected dive_ are shown in the respective
panels. On the other hand, if one highlights more than one dive the last
highlighted dive is the _selected dive_, but summary data of all
_highlighted dives_ are shown in the *Stats* tab of the *Dive Info* panel
(maximum, minimum and average depths, durations, water temperatures and SAC;
total time and number of dives selected).

[[S_ViewPanels]]

image::images/main_window_f20.jpg["The Main Window", align="center"]

The user can determine which of the four panels are displayed by selecting
the *View* option on the main menu. This feature gives the user several
choices of display:

*All*: show all four of the panels as in the screenshot above.

*Divelist*: Show only the Dive List.

*Profile*: Show only the Dive Profile of the selected dive.

*Info*: Show only the Dive Notes about the last selected dive and statistics for
all highlighted dives.

*Globe*: Show only the world map, centred on the last selected dive.

Like many other functions that can be accessed via the Main Menu, these
options can be triggered using keyboard shortcuts. The shortcuts for a
particular system are shown with an underline in the main menu
entries. Since different Operating Systems and the user chosen language may
cause _Subsurface_ to use different shortcut keys they are not listed here
in the user manual.

When the program is started for the first time, it shows no information at
all.  This is because the program doesn't have any dive information
available. In the following sections, the procedures to create a new logbook
will be described.

[[S_NewLogbook]]
Creating a new logbook
----------------------
Select _File -> New Logbook_ from the main menu. All existing dive data are
cleared so that new information can be added. If there are unsaved data in
an open logbook, the user is asked whether the open logbook should be saved
before a new logbook is created.

[[S_GetInformation]]
== Storing dive information in the logbook

Now that a new logbook was created, it is simple to add dive data to it.
_Subsurface_ allows several ways of adding dive data to a logbook, detailed
in the following sections.

If the user has a handwritten divelog, a spreadsheet or another form of
manually maintained divelog, dive data can be added to the logbook using one
of these approaches:

Enter dive information by hand. This is useful if the diver did not use a
dive computer and dives were recorded in a written logbook. See:
xref:S_EnterData[Entering dive information by hand]

Import dive log information that has been maintained either as a spreadsheet
or as a CSV file. Refer to: xref:S_Appendix_D[APPENDIX D: Exporting a
spreadsheet to CSV format] and the text about
xref:S_ImportingManualCSV[Importing dives from manually created CSV files]
and

If one has dives recorded using a dive computer, the depth profile of the
dive and a large amount of additional information can be accessed. These
dives can be imported from:

- The divecomputer itself. See: xref:S_ImportDiveComputer[Importing new dive
  information from a Dive Computer] or

Proprietary software distributed by manufacturers of dive computers. Refer
to: xref:S_ImportingAlienDiveLogs[Importing dive information from other
digital data sources or other data formats].

Import from spreadsheet or CSV files containing dive profiles.  See:
xref:S_ImportingCSVDives[Importing dives in CSV format from dive computers
or other dive log software]


[[S_EnterData]]
=== Entering dive information by hand

This is usually the approach for dives without a dive computer. The basic
record of information within _Subsurface_ is a dive. The most important
information in a simple dive logbook usually includes dive type, date, time,
duration, depth, the names of your dive buddy and of the dive master or dive
guide, and some remarks about the dive. _Subsurface_ can store much more
information than this for each dive. In order to add a dive to a dive log,
select _Log -> Add Dive_ from the Main Menu. The program then shows three
panels to enter information for a dive: two tabs in the *Dive Info* panel
(*Dive Notes* and *Equipment*), as well as the *Dive Profile* panel that
displays a graphical profile of each dive. These panels are respectively
marked [red]#A#, [red]#B# and [red]#C# in the figure below. Each of these
tabs will now be explained for data entry.

image::images/AddDive1_f20.jpg["FIGURE: Add dive", align="center"]

When one edits a field in Dive notes or Equipment panels, _Subsurface_
enters *Editing Mode*, indicated by the message in the blue box at the top
of the _Dive Notes_ panel (see the image below). This message is displayed
in all the panels under Dive notes and Equipment when in *Editing Mode*.

image::images/BlueEditBar_f20.jpg["Blue edit bar", align="center"]

The _Save_ button should only be selected after all the parts of a dive have
been entered.  When entering dives by hand, the _Info_, _Equipment_ and
_Profile_ tabs should be completed before saving the information. By
selecting the _Save_ button, a local copy of the information for this
specific dive is saved in memory. When one closes Subsurface, the program
will ask again, this time whether the complete dive log should be saved on
disk or not.

==== Dive Notes

This panel contains the date, time and place information for a particular
dive, environmental conditions, co-divers and buddies, as well as some
descriptive information. If one clicks on the *Dive Notes* tab, the
following fields are visible:

image::images/AddDive2_f20.jpg["FIGURE: The Dive Notes tab", align="center"]

The *Time* field reflects the date and the time of the dive. By clicking the
date, a calendar is displayed from which one can choose the correct
date. Press ESC to escape from the calendar.  The time values (hour and
minutes) can also be edited directly by clicking on each of them in the text
box and by overtyping the information displayed. The default date is the
present date and the default time is an hour in advance of the present time.

*Air and water temperatures*: the air and water temperatures during the
dive can be typed directly on the fields to the right of the Start time.
Temperature units are not needed, as they will be automatically supplied by
_Subsurface_. Only the numerical value must be
typed by the user (the units selected in the 'Preferences'
will determine whether metric or imperial units are used).

*Location*: Here the name of the dive site can be entered, e.g. "Tihany, Lake
Balaton,
Hungary". Auto completion of location names will make this easier if one
frequently dives at the same sites.

*Coordinates*: The geographic coordinates of the dive site should be entered
here. These can come from three sources:

One can find the coordinates on the world map in the bottom right hand part
of the Subsurface window. The map displays a green bar indicating "No
location data - Move the map and double-click to set the dive
location". Upon a double-click at the appropriate place, the green bar
disappears and the coordinates are stored.

The coordinates can be obtained from the _Subsurface_ Companion app if the
user has an Android device with GPS and if the coordinates of the dive site
were stored using that device.  xref:S_Companion[Click here for more
information]

The coordinates can be entered by hand if they are known, using one of four
formats with latitude followed by longitude:

	ISO 6709 Annex D format e.g. 30°13'28.9"N 30°49'1.5"E
	Degrees and decimal minutes, e.g. N30° 13.49760' , E30° 49.30788'
	Degrees minutes seconds, e.g. N30° 13' 29.8" , E30° 49' 1.5"
	Decimal degrees, e.g. 30.22496 , 30.821798

Southern hemisphere latitudes are given with a *S*, e.g. S30°, or with a
negative value, e.g. -30.22496. Similarly western longitudes are given with
a *W*, e.g. W07°, or with a negative value, e.g. -7.34323.

Please note that GPS coordinates of a dive site are linked to the Location
name - so adding coordinates to dives that do not have a location
description will cause unexpected behaviour (Subsurface will think that all
of these dives have the same location and try to keep their GPS coordinates
the same).

*Divemaster*: The name of the dive master or dive guide for this dive can be
entered here.
Again, this field offers auto completion based on the list of dive masters in
the current logbook.

*Buddy*: In this field one can enter the name(s) of the buddy / buddies
(separated by commas) who accompanied the user on the dive. Auto completion
is offered based on the list of buddies in the current logbook.

*Suit*: The type of diving suit used for the dive can be entered here.
As with the other items, auto completion of the suit description is available.
Some dry-suit users may choose to use this field to record what combination of
suit and thermal protection undersuit was used.

*Rating*: One can provide a subjective overall rating of the dive on a
5-point scale by clicking the appropriate star on the rating scale.

*Visibility*: Similarly, one can provide a rating of visibility during the
dive on a
5-point scale by clicking the appropriate star.

*Tags*: Tags that describe the type of dive performed may
be entered here (separated by commas). Examples of common tags are boat, drift,
training, cave etc. _Subsurface_ has many built-in tags. Auto completion is once again offered.
For instance, if +cav+ was typed, then the tags *cave* and *cavern* are
shown for the user to choose from.

*Notes*: Any additional information can be typed here.

The *Save* and *Cancel* buttons are used to save all the information for
tabs in the info panel and in the dive profile panel, so there's no need to
use them until ALL other information has been added. Here is an example of a
completed Dive Notes panel:

image::images/CompletedDiveInfo_f20.jpg["FIGURE: A completed Dive Notes tab", align="center"]

==== Equipment

The Equipment tab allows the user to enter information about the type of
cylinder and gas used, as well as the weights used for a dive. This is a
highly interactive part of _Subsurface_ and the information on cylinders and
gases (entered here) affects the behaviour of the dive profile (top
right-hand panel).

[[S_CylinderData]]
*Cylinders*: The cylinder information is entered through a dialogue that looks
like this:

image::images/Gas_dialogue1_f20.jpg["FIGURE:Initial cylinder dialogue", align="center"]

The + button at the top right allows the user to add more cylinders for this
dive.  The dark dustbin icon on the left allows one to delete information
for a particular cylinder. Note that it is not possible to delete a cylinder
if it is used during the dive. One cylinder is implicitly used in the dive,
even without a gas change event. Thus the first cylinder cannot be deleted
until another cylinder is created.

Start by selecting a cylinder type on the left-hand side of the table.  To
select a cylinder, click in the *Type* box.  This brings up a button that
can be used to display a dropdown list of cylinders:

image::images/Gas_dialogue2_f20.jpg["FIGURE:The cylinder drop-down list button", align="center"]

The drop-down list can be used to select the cylinder type used for the dive
or the user may start typing in the box which shows the available options
for the entered characters. The *Size* of the cylinder as well as its
working pressure (*WorkPress*) will automatically be shown in the
dialogue. If a cylinder is not shown in the dropdown list, type the name and
description of that cylinder into the *Type* field.

Next, indicate the starting pressure and the ending pressure of the gas used
during the dive. The unit of pressure (metric/imperial) corresponds to the
setting in the _Preferences_.

Finally, type in the gas mixture used in the *O2%* field. If air was used, a
value of 21% can be entered on this field, or it might be left blank. If
nitrox or trimix were used, their percentages of oxygen and/or helium must
be specified.  Any inappropriate fields should be left empty. After typing
the information for the cylinder, press _ENTER_ on the keyboard or click
outside the cell that contains the cursor. Information for any additional
cylinders can be added by using the + button at the top right
hand. Following is an example of a complete description for a dive made
using two cylinders (air and EAN50):

image::images/CylinderDataEntry3_f20.jpg["FIGURE: a completed cylinder dive information table", align="center"]

*Weights*: Information about the weight system used during a dive can be entered
using a dialogue very similar to that for the cylinder information. If the user
clicks the + button on the top right of the weights dialogue, the table looks
like this:

image::images/WeightsDataEntry1_f20.jpg["FIGURE: The Weights dialogue", align="center"]

If one then clicks on the *Type* field, a drop-down list becomes accessible
through a down-arrow:

image::images/WeightsDataEntry2_f20.jpg["FIGURE: Weights type drop-down list button", align="center"]

The drop-down list can then be used to select the type of weight system or
the user may start typing in the box which shows the available options for
the entered characters. In the *Weight* field, the weight used during the
dive must be typed. After typing the information for the weight system the
user must either press _ENTER_ on the keyboard or click outside the cell
that contains the cursor. It is possible to enter information for more than
one weight system by adding an additional system using the + button on the
top right hand. Weight systems can be deleted using the dustbin icon on the
left hand. Here is an example of information for a dive with two types of
weights: integrated and a weight belt:

image::images/WeightsDataEntry3_f20.jpg["FIGURE: A completed weights information table", align="center"]

There's NO need to click the _Save_ button before the dive profile has been
completed.

[[S_CreateProfile]]
==== Creating a Dive Profile

The *Dive Profile* (a graphical representation of the depth of the dive as a
function of time) is indicated in the panel on the top right hand of the
_Subsurface_ window. When a dive is manually added to a logbook,
_Subsurface_ presents a default dive profile that needs to be modified to
best represent the dive being described:

image::images/DiveProfile1_f20.jpg["FIGURE: Initial dive profile", align="center"]

_Modifying the dive profile_: When the cursor is moved around the dive
profile, its position is indicated by two coloured lines (red and green) as
shown below.  The depth and time that the cursor represents are indicated at
the top of the black information box (@ and D). The units (metric/imperial)
on the axes are determined by the *Preference* settings. The dive profile
itself comprises several line segments demarcated by waypoints (white dots
on the profile, as shown above). The default dive depth is 15 m.  If the
dive depth was 20 m then the user needs to drag the appropriate waypoints
downwards to represent 20 m. To add a waypoint, double-click on any line
segment. To move an additional waypoint, drag it.  To remove this waypoint,
right-click on it and choose "Remove this point" from the context menu. The
user needs to drag the waypoints to represent an accurate time duration for
the dive. Below is a dive profile that represents a dive to 20 m for 30 min,
followed by a 5 minute safety stop at 5 m.

image::images/DiveProfile2_f20.jpg["FIGURE: Edited dive profile", align="center"]

_Specifying the gas composition:_ The gas composition used is clearly
indicated along the line segments of the dive profile. This defaults to the
first gas mixture specified in the *Equipment* tab, which was air in the
case of the profile illustrated above. The gas mixtures of segments of the
dive profile can be edited. This is done by right-clicking on the particular
waypoint and selecting the appropriate gas from the context menu. Changing
the gas for a waypoint affects the gas shown in the segment _to the left_ of
that waypoint. Note that only the gases defined in the *Equipment* tab
appear in the context menu.

image::images/DiveProfile3_f20.jpg["FIGURE: Gas composition context menu", align="center"]

Below is the profile of a dive to 25 m for 30 min and with a switch from air
to EAN50 at the end of the duration at 20m. In this case the first cylinder
in the *Equipment* tab contained air and the second cylinder contained
EAN50.

image::images/DiveProfile4_f20.jpg["FIGURE: Completed dive profile", align="center"]

==== Saving the hand-entered dive information

The information entered in the *Dive Notes* tab, the *Equipment* tab as well
as the *Dive Profile* can now be saved in the user's logbook by using the
two buttons on the top right hand of the Dive Notes tab. If the _Save_
button is clicked, the dive data are saved in the current logbook. If the
_Cancel_ button is clicked, the newly entered dive data are discarded. When
exiting _Subsurface_, the user will be prompted once more to save the
logbook with the new dive(s).

[[S_ImportDiveComputer]]
=== Importing new dive information from a Dive Computer

==== Connecting and importing data from a dive computer.

The use of dive computers allows the collection of a large amount of
information about each dive, e.g. a detailed record of depth, duration,
rates of ascent/descent and of gas partial pressures. _Subsurface_ can
capture this information and present it as part of the dive information,
using dive information from a wide range of dive computers. The latest list
of supported dive computers can be found at:
link:http://subsurface-divelog.org/documentation/supported-dive-computers/[
Supported dive computers].

[icon="images/icons/warning2.png"]
[WARNING]
Several dive computers consume more power when they are in their
PC-Communication mode. **This could drain the dive computer's battery**. We
therefore recommend that the user checks if the dive computer is charged
when connected to the USB port of a PC. For example, several Suunto and
Mares dive computers do not recharge through the USB connection. Users
should refer to the dive computer's manual if they are unsure whether the
dive computer recharges its batteries while connected to the USB port.

To import dive information from a dive computer to a computer with
_Subsurface_, it is necessary that the two pieces of equipment communicate
with one another.  This involves setting up the communications port (or
mount point) of the computer with _Subsurface_ that communicates with the
dive computer. In order to set up this communication, one needs to find the
appropriate information to instruct _Subsurface_ where and how to import the
dive information.
xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix
A] provides the technical information to help the user achieving this for
different operating systems and
xref:_appendix_b_dive_computer_specific_information_for_importing_dive_information[Appendix
B] has dive computer specific information.

After this, the dive computer can be hooked up to the user's PC, which can
be achieved by following these steps:

1. The interface cable should be connected to a free USB port (or the Infra-red
	or Bluetooth connection set up as described later in this manual)

2. The dive computer should be placed into PC Communication mode.
	(Users should refer to the manual of their specific dive computer)

In _Subsurface_, from the Main Menu, the user must select _Import -> Import
From Dive Computer_.  Dialogue *A* in the figure below appears:


image::images/ImportFromDC1_f20.jpg["FIGURE: Download dialogue 1", align="center"]

Dive computers tend to keep a certain number of dives in their memory, even
though these dives have already been imported to _Subsurface_. For that
reason _Subsurface_ only imports dives that have not been uploaded
before. This makes the download process faster on most dive computers and
also saves battery power of the dive computer (at least for those not
charging while connected via USB).  If, for some reason, the user wishes to
import ALL dives from the dive computer, even though some may already be in
the logbook, then check the check box labelled _Force download of all
dives_.

The dialogue has two drop-down lists, *Vendor* and *Dive Computer*. On the
*vendor* drop-down list select the make of the computer, e.g.  Suunto,
Oceanic, Uwatec, Mares. On the *Dive Computer* drop-down list, the model
name of the dive computer must be selected, e.g. D4 (Suunto), Veo200
(Oceanic), or Puck (Mares).

The *Device or Mount Point* drop-down list contains the USB or Bluetooth
port name that _Subsurface_ needs in order to communicate with the dive
computer.  The appropriate port name must be selected. Consult
xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix
A] and
xref:_appendix_b_dive_computer_specific_information_for_importing_dive_information[Appendix
B] for technical details on how to find the appropriate port information for
a particular dive computer and, in some cases, how to do the correct
settings to the operating system of the computer on which _Subsurface_ is
running.

 - If all the dives on the dive computer need to be downloaded, check the
   checkbox _Force download of all dives_. Normally, _Subsurface_ only
   downloads dives after the date-time of the last dive in the *Dive List*
   panel. If one or more of your dives in _Subsurface_ have been accidentally
   deleted or if there are older dives that still need to be downloaded from
   the dive computer, this checkbox needs to be activated. Some dive computers
   (e.g. Mares Puck) do not provide a contents list to _Subsurface_ before the
   download in order to select only new dives.  Consequently, for these dive
   computers, all dives are downloaded irrespective of the status of this check
   box.

 - If the checkbox _Always prefer downloaded dives_ has been checked and,
   during download, dives with identical date-times exist on the dive computer
   and on the _Subsurface_ *Dive List* panel, the record in the _Subsurface_
   divelog will be overwritten by the record from the dive computer

 -  Do *not* check the checkboxes labelled _Save libdivecomputer logfile_ and
    _Save libdivecomputer dumpfile_. These are only used as diagnostic tools
    when problems with downloads are experienced (see below).

The _OK_ button must then be clicked. Dialogue *B* in the figure above
appears.

With communication established, one can see how the data are retrieved from
the dive computer.  Depending on the make of the dive computer and/or number
of recorded dives, this could take some time. The user should be
patient. The _Download_ dialogue shows a progress bar at the bottom of the
dialogue (for some dive computers the progress information could be
inaccurate as we cannot determine how much downloadable data there is until
all data have been downloaded). When the download of the dive information is
complete, all the imported dives appear in the *Dive List*, sorted by date
and time. Disconnect and switch off the dive computer to conserve its
battery power.  If a particular dive is selected, the *Dive Profile* panel
shows an informative graph of dive depth against time for that particular
dive.


If there is a problem in communicating with the dive computer, an error
message will be shown, similar to this text: "Unable to open /dev/ttyUSB0
Mares (Puck Pro)". Refer to the text in the box below.


****
*PROBLEMS WITH DATA DOWNLOAD FROM A DIVE COMPUTER?*
[icon="images/icons/important.png"]
[IMPORTANT]
Check the following:

Is the dive computer still in PC-communication or Upload mode?

Is the battery of the dive computer fully charged? If not then the battery
must be charged or replaced.

Is the connecting cable faulty? Does the cable work perfectly using other
software? Has it worked before, or is this the first time the cable is being
used? Are the contacts on the dive computer and the cable clean?

Consult
xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix
A] and make sure that the correct Mount Point was specified (see above).

On Unix-like operating systems, does the user have write permission to the
USB port? If not, consult
xref:_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer[Appendix
A]

If the _Subsurface_ computer does not recognise the USB adaptor by showing
an appropriate device name next to the Mount Point, then there is a
possibility that the cable or USB adaptor is faulty. A faulty cable is the
most common cause of communication failure between dive computer and
_Subsurface_ computer. It is also possible that the _Subsurface_ computer
cannot interpret the data. Perform a download for diagnostic purposes with
the following two check boxes checked in the download dialogue discussed
above:

	Save libdivecomputer logfile
	Save libdivecomputer dumpfile

*Important*: These check boxes are only used when problems are encountered
during the download process: under normal circumstances they should not be checked.
When checking these boxes, the user is prompted to select a folder to
save the information to. The default folder is the one in which the _Subsurface_
dive log is kept.

*Important:* _After downloading with the above checkboxes
checked, no dives are added to the
*Dive List* but two files are created in the folder selected above_:

	subsurface.log
	subsurface.bin

These files should be send to the _Subsurface_ mail list:
_subsurface@subsurface-divelog.org_ with a request for the files to be
analysed. Provide the dive computer make and model as well as contextual
information about the dives recorded on the dive computer.
****

[[S_DeviceNames]]
==== Changing the name of a dive computer

It may be necessary to distinguish between different dive computers used to
upload dive logs to _Subsurface_. For instance if one's partner's dive
computer is the same make and model as one's own and dive logs are uploaded
from both dive computers to the same _Subsurface_ computer, then one would
perhaps like to call one dc "Alice's Suunto D4" and the other one "Bob's
Suunto D4". Alternatively, perhaps a technical diver dives with two or more
dive computers of the same model, the logs of both (or all) being uploaded.
In this case it might be prudent to call one of them "Suunto D4 (1)" and
another one "Suunto D4 (2)". This is easily done in _Subsurface_.  On the
*Main Menu*, select _Log -> Edit device names_. A dialog opens, indicating
the current Model, ID and Nickname of the dive computers used for
upload. Edit the Nickname field for the appropriate dive computer. After
saving the Nickname, the dive logs show the nickname for that particular
device instead of the model name, allowing easy identification of devices.

[[S_EditDiveInfo]]
==== Updating the dive information imported from the dive computer.

The information from the dive computer is not complete and more details must
be added in order to have a fuller record of the dives. To do this, the
*Dive Notes* and the *Equipment* tabs on the top left hand of the
_Subsurface_ window should be used.

==== Dive Notes

The date and time of the dive, gas mixture and (often) water temperature is
shown as obtained from the dive computer, but the user needs to add
additional information by hand in order to have a more complete dive
record.  If the contents of this tab is changed or edited in any way, the
message in a blue box at the top of the panel indicates that the dive is
being edited. If one clicks on the *Dive Notes* tab, the following fields
are visible:

image::images/AddDive3_f20.jpg["FIGURE: The Dive Notes tab", align="center"]

The *Time* field reflects the date and time of the dive. By clicking the
date, a calendar is displayed from which one can choose the correct
date. Press ESC to close the calendar.  The time values (hour and minutes)
can also be edited directly by clicking on each of them in the text box and
by overtyping the information displayed.

*Air/water temperatures*: Air and water temperatures during the dive are shown
in these fields to the right of the Start time. Many dive computers supply water
temperature information and this field may therefore contain information obtained from the dive computer.
If air temperature is not provided by the dive computer, the first temperature reading
might be used for the air temperature. Generally this is close enough to the real air temperature as
the change in the temperature sensor reading is quite slow to follow the changes in the environment.
If editing is required, only a value is required, the units of temperature will be
automatically supplied by
_Subsurface_ (according to the _Preferences_, metric or imperial units will
be used).

*Location*: In this field one should type in text that describes the site
where the dive was performed, e.g. "Tihany, Lake Balaton, Hungary".
Auto completion of location names will
make this easier if one frequently dives at the same sites.

*Coordinates*: The geographic coordinates of the dive site should be entered
here. These can come from three sources:

The user can find the coordinates on the world map in the bottom right hand
part of the Subsurface window. The map displays a green bar indicating "Move
the map and double-click to set the dive location". Double-click at the
appropriate place, the green bar disappears and the coordinates are stored.

The user can obtain the coordinates from the _Subsurface_ Companion app if
an Android device with GPS was used and if the coordinates of the dive site
were stored using that device.  xref:S_Companion[Click here for more
information]

The coordinates can be entered by hand if they are known, using one of four
formats with latitude followed by longitude:

	ISO 6709 Annex D format e.g. 30°13'28.9"N 30°49'1.5"E
	Degrees and decimal minutes, e.g. N30° 13.49760' , E30° 49.30788'
	Degrees minutes seconds, e.g. N30° 13' 29.8" , E30° 49' 1.5"
	Decimal degrees, e.g. 30.22496 , 30.821798

Southern hemisphere latitudes are given with a *S*, e.g. S30°, or with a
negative value, e.g. -30.22496. Similarly, western longitudes are given with
a *W*, e.g. W07°, or with a negative value, e.g. -7.34323.

Please note that GPS coordinates of a dive site are linked to the Location
name - so adding coordinates to dives that do not have a location
description will cause unexpected behaviour (Subsurface will think that all
of these dives have the same location and try to keep their GPS coordinates
the same).

*Divemaster*: The name of the dive master or dive guide for this dive should be
entered in this field
which offers auto completion based on the list of dive masters in
the current logbook.

*Buddy*: In this field, one enters the name(s) of the buddy / buddies
(separated with commas) who accompanied him/her on the
dive. Auto completion based on the list of buddies in the current logbook is
offered.

*Suit*: Here the type of diving suit used for the dive can be entered.
Auto completion of the suit description is available.
Some dry-suit users may choose to use this field to record what combination of
suit and thermal protection undersuit was used.

*Rating*: One can provide a subjective overall rating of the dive on a
5-point scale by clicking the appropriate star on the rating scale.

*Visibility*: Similarly, one can provide a rating of visibility during the
dive on a
5-point scale by clicking the appropriate star.

*Tags*: Tags that describe the type of dive performed can be entered
here (separated by commas). Examples of common tags are boat, drift, training,
cave, etc.
_Subsurface_ has many built-in tags. If the user starts typing a tag, the
program
will list the tags that correspond to the typing. For instance, if the user
typed
+cav+, then the tags *cave* and *cavern* are shown for the user to choose from.

*Notes*: Any additional information for the dive can be entered here.

The *Save* and *Cancel* buttons are used to save all the information for
tabs in the info panel and in the dive profile panel, so there's no need to
use them until ALL other information has been added. Here is an example of a
completed Dive Notes panel:

image::images/CompletedDiveInfo_f20.jpg["FIGURE: A completed Dive Notes tab", align="center"]

==== Equipment

The Equipment tab allows one to enter information about the type of cylinder
and gas used as well as the weights used for the dive. The message in a blue
box at the top of the panel:

image::images/BlueEditBar_f20.jpg["FIGURE: Blue edit bar", align="center"]

indicates that the dive is being edited. This is a highly interactive part
of _Subsurface_ and the information on cylinders and gases (entered here)
determines the behaviour of the dive profile (top right-hand panel).

*Cylinders*: The cylinder information is entered through a dialogue that looks
like this:

image::images/DC_gas-dialogue1_f20.jpg["FIGURE: Initial cylinder dialogue", align="center"]

In most cases _Subsurface_ obtains the gas used from the dive computer and
automatically inserts the gas composition(% oxygen) in the table. The +
button at the top right allows the user to add more cylinders for this
dive. The dark dustbin icon on the left allows the deletion of information
for a cylinder.  Note that it is not possible to delete a cylinder if it is
used during the dive. A cylinder might be implicitly used in the dive, even
without a gas change event.

The user should start by selecting a cylinder type on the left-hand side of
the table.  To select a cylinder, the *cylinder type* box should be
clicked. This brings up a list button that can be used to display a dropdown
list of cylinders:

image::images/DC_gas-dialogue2_f20.jpg["FIGURE: The cylinder drop-down list button", align="center"]

The drop-down list can then be used to select the cylinder type that was
used for this dive or the user may start typing in the box which shows the
available options for the entered characters. The *Size* of the cylinder as
well as its working pressure (*WorkPress*) will automatically be shown in
the dialogue.

Next one must indicate the starting pressure and the ending pressure of the
specified gas during the dive. The unit of pressure (metric/imperial)
corresponds to the settings chosen in the _Preferences_.

Finally, provide the gas mixture used. If air was used, the value of 21% can
be entered or this field can be left blank. If nitrox or trimix were used,
their percentages of oxygen and/or helium should be entered.  Any
inappropriate fields should be left empty. After typing the information for
the cylinder, either press _ENTER_ on the keyboard or click outside the cell
that contains the cursor. Information for any additional cylinders can be
added by using the + button at the top right hand. Following is an example
of a complete description for a dive using two cylinders (air and EAN50):

image::images/CylinderDataEntry3_f20.jpg["FIGURE: a completed cylinder dive information table", align="center"]

*Weights*: Information about the weight system used can be entered
using a dialogue very similar to that of the cylinder information. If one
clicks
the + button on the top right of the weights dialogue, the table looks like
this:

image::images/WeightsDataEntry1_f20.jpg["FIGURE:The Weights dialogue", align="center"]

By clicking on the *Type* field, a drop-down list becomes accessible through
a down-arrow:

image::images/WeightsDataEntry2_f20.jpg["FIGURE:Weights type drop-down list button", align="center"]

The drop-down list can then be used to select the type of weight system used
during the dive or the user may start typing in the box which shows the
available options for the entered characters.  In the *Weight* field, type
in the amount of weight used during the dive. After specifying the weight
system, the user can either press _ENTER_ on the keyboard or click outside
the cell with the cursor.  It is possible to enter information for more than
one weight system by adding an additional system using the + button on the
top right hand. Weight systems can be deleted using the dustbin icon on the
left hand. Here is an example of information for a dive with two types of
weights: integrated as well as a weight belt:

image::images/WeightsDataEntry3_f20.jpg["FIGURE: A completed weights information table", align="center"]

==== Editing several selected dives simultaneously

_METHOD 1_: After uploading dives from a dive computer, the dive profiles of
the uploaded dives are shown in the *Dive profile* tab, as well as a few
items of information in the *Dive Notes* tab (e.g. water temperature) and in
the *Equipment* tab (e.g. gas pressures and gas composition). However the
other fields remain empty.  It may be useful to simultaneously edit some of
the fields in the *Dive Notes* and *Equipment* tabs.  For instance, it is
possible that a diver performed several dives during a single day, using
identical equipment while diving at the same dive site or with the same dive
master and/or buddy or tags. Instead of completing the information for each
of these dives separately, one can select all the dives for that day in the
*Dive List* and insert the same information in the *Dive Notes* and
*Equipment* fields that need identical information. This is achieved by
editing the dive notes or the equipment for any one of the selected dives.

The simultaneous editing only works with fields that do not already contain
information.  This means that, if some fields have been edited for a
particular dive among the selected dives, these are not changed while
editing the dives simultaneously. Technically, the rule for editing several
dives simultaneously is: if the data field being edited contains _exactly
the same information_ for all the dives that have been selected, the new,
edited information is substituted for all the selected dives, otherwise only
the edited dive is changed, even though several dives have been selected in
the *Dive List*. This greatly speeds up the completion of the dive log after
several similar dives.

[[S_CopyComponents]]
_METHOD 2_:There is a different way of achieving the same goal. Select a
dive with all the appropriate information typed into the *Dive Notes* and
*Equipment* tabs. Then, from the main menu, select _Log -> Copy dive
components_.  A box is presented with a selection of check boxes for most of
the fields in the *Dive Notes* and *Equipment* tabs.  Select the fields to
be copied from the currently selected dive, then select _OK_. Now, in the
*Dive List*, select the dives into which this information is to be
pasted. Then, from the main menu, select _Log -> Paste dive components_.
All the selected dives now contain the data initially selected in the
original source dive log.

==== Adding Bookmarks to a dive

Many divers wish to annotate their dives with text that indicate particular
events during the dive, e.g. "Saw dolphins", or "Released surface
buoy". This is easily done:

Right-click at the appropriate point on the dive profile.  This brings up
the dive profile context menu. Select _Add bookmark_. A red flag is placed
on the dive profile at the point that was initially selected (see *A*
below).

 - Right-click on the red flag. This brings up the context menu (see *B*
   below). Select _Edit name_.

A text box is shown. Type the explanatory text for the bookmark (see *C*
below). Select _OK_.  This saves the text associated with the bookmark.

If one hovers using the mouse over the red bookmark, the appropriate text is
shown at the bottom of the information box (see *D* below).

image::images/Bookmarks.jpg["FIGURE: Bookmark dialog", align="center"]


==== Saving the updated dive information

The information entered in the *Dive Notes* tab and the *Equipment* tab can
be saved by using the two buttons on the top right hand of the *Dive Notes*
tab. If the _Save_ button is clicked, the dive data are saved. If the
_Cancel_ button is clicked, then the newly entered dive data are deleted,
although the dive profile obtained from the dive computer will be
retained. When the user exits _Subsurface_ there is a final prompt to
confirm that the new data should be saved.

=== Importing dive information from other digital data sources or other data formats

[[S_ImportingAlienDiveLogs]]

If a user has been diving for some time, it is possible that several dives
were logged using other dive log software. This information does not need
retyping because these dive logs can probably be imported into
_Subsurface_. _Subsurface_ will import dive logs from a range of other dive
log software. While some software is supported natively, for others the user
has to export the logbook(s) to an intermediate format so that they can then
be imported by _Subsurface_.  Currently, _Subsurface_ supports importing CSV
log files from several sources.  APD LogViewer, XP5, Sensus and Seabear
files are preconfigured, but because the import is flexible, users can
configure their own imports.  Manually kept log files (e.g. in spreadsheet)
can also be imported by configuring the CSV import.  _Subsurface_ can also
import UDDF and UDCF files used by some divelog software and some dive
computers, like the Heinrichs & Weikamp DR5. Finally, for some divelog
software like Mares Dive Organiser it is currently suggested to import the
logbooks first into a webservice like _divelogs.de_ and then import them
from there with _Subsurface_, as divelogs.de supports a few additional
logbook formats that _Subsurface_ currently cannot parse.

If the format of other software is supported natively on Subsurface, it
should be sufficient to select either _Import->Import log files_ or
_File->Open log file_. _Subsurface_ supports the data formats of many dive
computers, including Suunto and Shearwater. When importing dives,
_Subsurface_ tries to detect multiple records for the same dive and merges
the information as best as it can. If there are no time zone issues (or
other reasons that would cause the beginning time of the dives to be
significantly different) _Subsurface_ will not create duplicate entries.

==== Using the universal import dialogue
[[Unified_import]]

Importing dives from other software is performed through a universal
interface that is activated by selecting _Import_ from the Main Menu, then
clicking on _Import Log Files_. This brings up the dialogue *A* below.

image::images/Import1_f20.jpg["FIGURE: Import dialogue: step 1", align="center"]

Towards the bottom right is a dropdown selector with a default label of
_Dive Log Files_ which gives access to the different types of direct imports
available, as in dialogue *B*, above. Currently these are:

 - XML-formatted dive logs (DivingLog 5.0, MacDive and several other dive log
   systems)
 - UDDF-formatted dive logs (e.g. Kenozoooid)
 - UDCF-formatted dive logs
 - Poseidon MkVI CCR logs
 - JDiveLog
 - Suunto Dive Manager (DM3 and DM4)
 - CSV (text-based and spreadsheet-based) dive logs, including APD CCR logs

Selecting the appropriate file in the file list of the dialogue opens the
imported dive log in the _Subsurface_ *Dive List*. Some other formats, not
accessible through the Import dialogue are also supported, as explained
below.

==== Importing dive logs from closed circuit rebreather (CCR) systems

[icon="images/APD.jpg"]
[NOTE]
Closed system rebreathers use advanced technology to recirculate gas that
has been breathed while doing two things to maintain a breathable oxygen
concentration:
a) remove carbon dioxide from the gas that has been exhaled
regulate the oxygen concentration to remain within safe diving limits.
Currently, within _Subsurface_, the Poseidon MkVI Discovery is the best
supported CCR dive computer. The CCR interface of _Subsurface_ is currently
experimental and under active development. In contrast to a conventional
open circuit dive computer, a CCR system computer does not allow the
download of a log containing multiple dives. Rather, each dive is stored
independently. This means that _Subsurface_ cannot download a dive log
directly from a CCR dive computer, but that it imports CCR dive logs in the
same way that it imports dive log data from other databases.

===== Import a CCR dive

See the section dealing with xref:S_ImportingAlienDiveLogs[Importing dive
information from other digital sources]. From the main menu of _Subsurface_,
select _Import->Import log files_ to bring up the
xref:Unified_import[universal import dialogue]. As explained in the previous
section, the bottom right hand of the import dialogue contains a dropdown
list of appropriate devices that currently includes an option for MkVI
files. Having selected the appropriate CCR format and the directory where
the original dive logs have been stored from the CCR dive computer, one can
select a particular dive log file (in the case of the MkVI it is a file with
a .txt extension). After selecting the appropriate dive log, activate the
_Open_ button at the bottom right hand of the universal import dialogue.

===== Displayed information for a  dive

_Partial pressures of gases_: The graph of oxygen partial pressure shows the
information from the oxygen sensors of the CCR equipment. In the case of the
Poseidon MKVI, the mean value of the two oxygen sensors are shown. In the
case of the APD equipment, the mean of the three oxygen sensors are
shown. If one sensor shows a very different oxygen PO2 reading compared to
the others, the divergent sensor is ignored. For CCR dives the graph for
oxygen partial pressure should be fairly flat, reflecting the setpoint
settings during the dive.  Partial pressures for nitrogen (and helium, if
applicable) are shown in the usual way as for other dives.

_Cylinder pressures_: CCR dive computers like the Poseidon MkVI record the
pressures of the oxygen and diluent cylinders. The pressure of the oxygen
cylinder is shown on the dive profile. In addition, start and end pressures
for both oxygen and diluent cylinders are shown in the _Equipment Tab_.

_Equipment-specific information_: Equipment-specific information gathered by
_Subsurface_ is shown in the _Extra data_ tab. This may include setup
information or metadata about the dive.

More equipment-specific information for downloading CCR dive logs can be
found in xref:S_PoseidonMkVI[Appendix B].

==== Importing from Mares Dive Organiser V2.1

Since Mares utilise proprietary Windows software not compatible with
multi-platform applications, these dive logs cannot be directly imported
into _Subsurface_. Mares dive logs need to be imported using a three-step
process, using _www.divelogs.de_ as a mechanism to extract the dive log
information.

The dive log data from Mares Dive Organiser need to be exported to the user's
desktop, using
 a _.sdf_ file name extension. Refer to xref:Mares_Export[Appendix C] for more
information.
Data should then be imported into _www.divelogs.de_. One needs to create a user
account in
_www.divelogs.de_, log into that web site, then
select _Import Logbook -> Dive Organiser_ from the menu on the left hand side.
The instructions must be carefully followed to transfer the dive information
(in _.sdf_ format) from the Dive Organiser database to _www.divelogs.de_.
Finally,  import the dives
from _divelogs.de_ to _Subsurface_, using the instructions below.


[[S_ImportingDivelogsDe]]
==== Importing dives from *divelogs.de*

The import of dive information from _divelogs.de_ is simple, using a single
dialogue box. The _Import->Import form Divelogs.de_ option should be
selected from the Main Menu. This brings up a dialogue box (see figure on
left [*A*] below). Enter a user-ID and password for _divelogs.de_ into the
appropriate fields and then select the _Download_ button. Download from
_divelogs.de_ starts immediately, displaying a progress bar in the dialogue
box. At the end of the download, the success status is indicated (see figure
on the right [*B*], below). The _Apply_ button should then be selected,
after which the imported dives appear in the _Subsurface_ *Dive List* panel.

image::images/Divelogs1.jpg["FIGURE:Download from Divelogs.de", align="center"]

[[S_ImportingCSVData]]
==== Importing data in CSV format

A comma-separated file (.csv) can be used to import dive information either
as dive profiles (as in the case of the APD Inspiration and Evolution closed
circuit rebreathers) or as dive metadata (in case the user keeps dive data
in a spreadsheet). For an introduction to CSV-formatted files see
xref:S_CSV_Intro[A Diver's Introduction To CSV Files].

[icon="images/icons/important.png"]
[IMPORTANT]
The CSV import has a couple of caveats. You should avoid some special
characters like ampersand (&), less than (<), greater than (>) and double
quotes ("), the latter if quoting text cells. The file should use UTF-8
character set, if having non-ASCII characters. Also the size of the CSV file
might cause problems. Importing 100 dives at a time (without dive profile)
has worked previously, but larger files might exceed limits of the parser
used. When having problems with CSV imports, try first with a smaller sample
to make sure everything works.

[[S_ImportingCSVDives]]
===== Importing dives in CSV format from dive computers or other dive log software

CSV files are normally organised into a single line that provides the
headers (or _field names_) of the data columns, followed by the data, one
record per line. CSV files can be opened with a normal text editor.  For
information of how to export a spreadsheet in CSV format see
xref:S_Appendix_D[APPENDIX D: Exporting a spreadsheet to CSV format].

Before being able to import the data to _Subsurface_ one needs to know:

Which character separates the different columns within a single line of
data? This field separator should be either a comma (,) or a TAB character.
This can be determined by opening the file with a text editor. If it is
comma-delimited, then the comma characters between the values are clearly
visible. If no commas are evident and the numbers are aligned in columns,
the file is probably TAB-delimited (i.e. it uses a TAB as a field separator,
as in the above example).

Which data columns need to be imported into _Subsurface_? The Dive Time and
Depth columns are always required. Open the file using a text editor and
note the titles of the columns to be imported and their column positions.

c. Is the numeric information (e.g. dive depth) in metric or in imperial unis?

Armed with this information, importing the data into _Subsurface_ is
straightforward. Select _Import->Import Log Files_ from the main menu. In
the resulting file selection menu, select _CSV files_, after which a common
configuration dialog appears for all the files with a CSV extension:

image::images/Import_CSV1.jpg["FIGURE: CSV download dialogue", align="center"]

There are pre-configured definitions for some dive computers, e.g. the APD
rebreathers. If the user's dive computer is on this list, it should be
selected using the dropdown box labeled _Pre-configured imports_.

If the dive computer is not on the pre-configured list, the user must select
the _Field Separator_ (TAB or comma) for the particular CSV file, using the
appropriate dropdown list. For each data column used for import, the user
must check the appropriate check box and indicate in which column these data
are found.

Finally _OK_ should be clicked and the dive(s) are imported and listed in
the *Dive List* tab of _Subsurface_.


[[S_ImportingManualCSV]]
==== Importing dives from a manually kept CSV file or a spreadsheet

[[S_CSV_Intro]]
****
*A Diver's Introduction To CSV Files*
[icon="images/icons/important.png"]
[IMPORTANT]

CSV is an abbreviation for a data file format: _Comma-Separated
Variables_. It is a file format allowing someone to view or edit the
information using a text editor such as Notebook (Windows), gedit (Linux) or
TextWrangler (OS/X). The two main advantages of the CSV format is that the
data are easily editable as text without any proprietary software and
ensuring all information is human-readable, not being obscured by the any
custom or proprietary attributes that proprietary software insert into
files.  Because of its simplicity the CSV format is used as an interchange
format between many software packages, e.g. between spreadsheet,
statistical, graphics, database and diving software. Within _Subsurface_,
CSV files can also be used to import information from other sources such as
spreadsheet-based dive logs and even from some dive computers.

CSV files can be created or edited with a normal text editor. The most
important attribute of a CSV file is the _field separator_, the character
used to separate fields within a single line. The field separator is
frequently a comma, a colon, a SPACE character or a TAB character. When
exporting data from spreadsheet software, the field separator needs to be
specified in order to create the CSV file. CSV files are normally organised
into a single line that provides the headers (or _field names_) of the data
columns, followed by the data, one record per line. Note that each field
name may comprise more than one word separated by spaces; for instance _Dive
site_, below. Here is an example of dive information for four dives using a
comma as a field separator:

	Dive site,Dive date,Time,Dive_duration, Dive_depth,Dive buddy
	Illovo Beach,2012-11-23,10:45,46:15,18.4,John Smith
	Key Largo,2012-11-24,09:12,34:15,20.4,Jason McDonald
	Wismar Baltic,2012-12-01,10:13,35:27,15.4,Dieter Albrecht
	Pulau Weh,2012-12-20,09:46,55:56,38.6,Karaeng Bontonompo

In this format the data are not easily read by a human. Here is the same
information in TAB-delimited format:

	Dive site	Dive date	Time	Dive_duration	Dive_depth	Dive buddy
	Illovo Beach	2012-11-23	10:45	46:15	18.4	John Smith
	Key Largo	2012-11-24	09:12	34:15	20.4	Jason McDonald
	Wismar Baltic	2012-12-01	10:13	35:27	15.4	Dieter Albrecht
	Pulau Weh	2012-12-20	09:46	55:56	38.6	Karaeng Bontonompo

It is clear why many people prefer the TAB-delimited format to the
comma-delimited format. The disadvantage is that one cannot see the TAB
characters. For instance, the space between _Dive_ and _date_ in the top
line may be a SPACE character or a TAB character (in this case it is a SPACE
character: the tabs are before and after _Dive date_). If the field names in
the first line are long, the alignment with data in the other lines cannot
be maintained. Here is a highly simplified and shortened TAB-delimited
example of a CSV dive log from an APD closed-circuit rebreather (CCR) dive
computer:

	Dive Time (s)	Depth (m)	pO₂ - Setpoint (Bar) 	pO₂ - C1 Cell 1 (Bar)	Ambient temp. (Celsius)
	0       0.0     0.70    0.81    13.1
	0       1.2     0.70    0.71    13.1
	0       0.0     0.70    0.71    13.1
	0       1.2     0.70    0.71    13.2
	0       1.2     0.70    0.71    13.1
	10      1.6     0.70    0.72    12.7
	20      1.6     0.70    0.71    12.6
	30      1.7     0.70    0.71    12.6
	40      1.8     0.70    0.68    12.5

CSV files can therefore be used in many contexts for importing data into a
_Subsurface_ dive log.

An important aspect of the CSV format required by _Subsurface_ is the
_Column Mapping_. In the example from different dive sites above, each line
of data is organised as follows:

	Column 1:	Dive site (location)
	Column 2:	Dive date
	Column 3:	Dive time
	Column 4:	Dive duration
	Column 5:	Maximum dive depth (m)
	Column 6:	Name of dive buddy

_Subsurface_ requires the column number of each of these data items. For
these data the column specification may look like this:

image::images/CSV_column_definition.jpg["FIGURE: CSV column definition", align="center"]

Knowledge of a few basic things about he content of the CSV file allows a
smooth import of the dives into _Subsurface_.

****

If one keeps dive logs in a spreadsheet, there is an option to import those
dives, exported as a CSV file. See xref:S_Appendix_D[APPENDIX D: Exporting a
spreadsheet to CSV format] for information of how to export a spreadsheet in
CSV format.  When importing manually kept log files into _Subsurface_, the
information needed is quite different from that accessible using a dive
computer, as we are importing only summary data, not depth profile samples.

When importing dives in CSV format (see above), one needs to know the
internal format of the CSV data to import.

Which character separates the different columns within a single line of
data? A recommended field separator for the export is TAB, as commas might
be part of the decimal data values themselves. Therefore the use of an
appropriate field separator is very important. When exporting data from a
spreadsheet it is likely to request the user to supply an appropriate field
separator character.

Which columns need to be imported into _Subsurface_? Currently there are not
any mandatory input fields, but some, e.g. dive duration are crucial for the
log file to make any sense. Possible options can be seen in the image below
and one should include as many as possible of the fields available in the
original log file.

Units used for depth, weight and temperature. We consider depth to be either
feet or meters, weight kilograms or pounds and temperature either Celsius or
Fahrenheit. However, the users can select _Metric_ or _Imperial_ in the
*Preferences* tab of _Subsurface_. No mixture of unit systems is allowed for
the different fields.

Importing manually kept CSV log files is quite straight forward, but there
might be many fields and counting the field numbers is error
prone. Therefore validation of the data to be imported is critical.

To import the dives, select _Import->Import Log Files_ from the menu bar. If
the CSV option in the dropdown list is selected and the file list includes
file names ending with .CSV, one can select the _Manual dives_ tab that will
bring up the following configuration dialog:

image::images/Import_CSV2.jpg["FIGURE: Download dialog for Manual CSV logs", align="center"]

Check the check boxes corresponding to the data in the original import
file.  For each of the checked data items, a corresponding column number
needs to be entered. For instance in the image above, the name of the dive
site (i.e. location)  is located as the 11th item (or column) on each line
of the CSV import file.  The input fields can be configured as appropriate,
and when everything is done the _OK_ button should be selected to perform
the import. New dives should appear in the *Dive List* area of _Subsurface_.


[[S_Companion]]
=== Importing GPS coordinates with the _Subsurface Companion App_ for mobile phones

Using the *Subsurface Companion App* on an Android device with a GPS, the
coordinates for the diving location can be automatically passed to the
_Subsurface_ dive log. The Companion App stores the dive locations on a
dedicated Internet-based file server. _Subsurface_, in turn, can collect the
localities from the file server.

To do this:

==== Create a Companion App account

Register on the http://api.hohndel.org/login/[_Subsurface companion web
page_].  A confirmation email with instructions and a personal *DIVERID*
will be sent, a long number that gives access to the file server and
Companion App capabilities.

Download the app from
https://play.google.com/store/apps/details?id=org.subsurface[Google Play
Store] or from
http://f-droid.org/repository/browse/?fdfilter=subsurface&fdid=org.subsurface[F-Droid].

==== Using the Subsurface companion app on a smartphone

On first use the app has three options:

_Create a new account._ Equivalent to registering in _Subsurface_ companion
page using an Internet browser. One can request a *DIVERID* using this
option, but this is supplied via email and followed up by interaction with
the http://api.hohndel.org/login/[_Subsurface companion web page_] in order
to activate the account.

_Retrieve an account._ If users forgot their *DIVERID* they will receive an
email to recover the number.

_Use an existing account._ Users are prompted for their *DIVERID*. The app
saves this *DIVERID* and does not ask for it again unless one uses the
_Disconnect_ menu option (see below).

[icon="images/icons/important.png"]
[IMPORTANT]
In the _Subsurface_ main program, the *DIVERID* should also be entered on
the Default Preferences panel, obtained by selecting
_File->Preferences->Defaults_ from the main menu in _Subsurface_ itself.
This facilitates synchronisation between _Subsurface_ and the Companion App.

===== Creating new dive locations

Now one is ready to get a dive position and send it to the server. The
Android display will look like the left hand image (*A*) below, but without
any dives.

Touch the "+" icon on the top right to add a new dive site, a menu will be
showed with 3 options:

Current: A prompt for a place name (or a request to activate the GPS if it
is turned off) will be displayed, after which the current location is saved.

Use Map: This option allows the user to fix a position by searching a world
map. A world map is shown (see *B* below) on which one should indicate the
desired position with a _long press_ on the touch sensitive screen (if the
marked location is erroneous, simply indicate a new location)  and select
the check symbol in the upper right. A dialog is shown allowing to enter the
name of the dive location and the date-time of the dive (see *C* below). In
order to import this dive location in _Subsurface_ it's advisable to set the
time to agree with the time of that dive on the dive computer.

image::images/Companion_5.jpg["FIGURE: Companion App, add location using map", align="center"]


Import local GPX file: The android device searches for .gpx files and
located archives will be shown. The selected .gpx file is opened and the
stored locations shown. Now one needs to select the appropriate locations,
then select the tab in the upper right, after which the locations will be
sent to the web service and added to the list on the Android device.

===== Dive lists of dive locations

The main screen shows a list of dive locations, each with a name, date and
time (see *A* below). Some locations may have an arrow-up icon over the
selection box to the left indicating that they require upload to the
server. One can select individual dive locations from the list. A selected
location has a check mark in the selection box on the left. Group operations
(such as _Delete_ or _Send_)  are performed on several locations that are
selected.

Dive locations in this list can be viewed in two ways: a list of locations
or a map indicating the dive locations. The display mode (List or Map) is
changed by selecting _Dives_ at the top left of the screen (see *A* below)
and then selecting the display mode. The display mode can be changed either
from the list of locations or from the map (see *B* below). If one selects a
location (on the list or on the map), an editing panel opens (see *C* below)
where the dive description or other details may be changed.

image::images/Companion_4.jpg["FIGURE: Companion App, add location using map", align="center"]


When one clicks on a dive (*not* selecting the check box), the name given to
it, date/time and GPS coordinates will be shown, with two options at the top
of the screen:

- Edit (pencil): Change the text name or other characteristics of the dive
  location.

- Maps: Display a map showing the dive location.

After editing and saving a dive location (see *C* above), one needs to
upload it to the web service, as explained below.

===== Uploading dive locations

There are several ways to send locations to the server.  The easiest is by
simply selecting the locations (See *A* below) and then touching the right
arrow at the top right of the screen.

[icon="images/icons/important.png"]
[IMPORTANT]
Users must be careful, as the trash icon on the right means exactly what it
should; it deletes the selected dive location(s).

image::images/Companion_1.jpg["FIGURE: Screen shots (A-B) of companion app", align="center"]


After a dive trip using the Companion App, all dive locations are ready to
be downloaded to a _Subsurface_ dive log (see below).


===== Settings on the Companion app

Selecting the _Settings_ menu option results in the right hand image above
(*B*).

===== Server and account

- _Web-service URL._ This is predefined (http://api.hohndel.org/)

_User ID._ The DIVERID obtained by registering as described above. The
easiest way to obtain it is simply to copy and paste from the confirmation
email but, of course, users can also type this information.

===== Synchronisation

_Synchronize on startup._ If selected, dive locations in the Android device
and those on the web service synchronise each time the app is started.

_Upload new dives._ If selected, each time the user adds a dive location it
is automatically sent to the server.

===== Background service
Instead of entering a unique dive location, users can leave the service
running in the background of their Android device, allowing the continuous
collection of GPS locations.


The settings below define the behaviour of the service:

_Min duration._ In minutes. The app will try to get a location every X
minutes until stopped by the user.

- _Min distance._ In meters. Minimum distance between two locations.

- _Name template._ The name the app will use when saving the locations.

[icon="images/icons/info.jpg"]
[TIP]
_How does the background service work?_ Assuming the user sets 5 minutes and
50 meters in the settings above, the app will start by recording a location
at the current location, followed by another one at every 5 minutes *or*
every time one moves 50m from previous location.  If subsequent locations
are within a radius of 50 meters from the previous one, a new location is
not saved. If the user is not moving, only one location is saved, but if the
user is moving, a trace of the route is obtained by saving a location every
50 meters.

===== Other

_Mailing List._ The mail box for _Subsurface_. Users can send an email to
the Subsurface mailing list.

- _Subsurface website._ A link to the URL of Subsurface web

- _Version._ Displays the current version of the Companion App.

===== Search

Search the saved dive locations by name or by date and time.

===== Start service

Initiates the _background service_ following the previously defined
settings.

===== Disconnect

This is a badly named option that disconnects the app from the server by
resetting the user ID in the app, showing the first screen where an account
can be created, retrieve the ID for an existing account or use the users own
ID. The disconnect option is useful if a user's Android device was used to
download the dive locations of another registered diver.

===== Send all locations

This option sends all locations stored in the Android device to the server.


==== Downloading dive locations to the _Subsurface_ divelog

Download dive(s) from a dive computer or enter them manually into
_Subsurface_ before obtaining the GPS coordinates from the server. The
download dialog can be reached via _Ctrl+G_ or from the _Subsurface_ Main
Menu _Import -> Import GPS data from Subsurface Service_, resulting in the
image on the left (*A*), below. On first use the DIVERID text box is
blank. Provide a DIVERID, then select the _Download_ button to initiate the
download process, after which the screen on the right (*B*) below appears:

image::images/DownloadGPS.jpg["FIGURE: Downloading Companion app GPS data", align="center"]

Note that the _Apply_ button is now active. By clicking on it, users can
update the locations of the newly entered or uploaded dives in _Subsurface_
which applies the coordinates and names entered on the app for all the new
dives that match the date-times of the uploaded GPS localities. If one has
entered the name of the dive location in _Subsurface_ before downloading the
GPS coordinates, this name will take precedence over downloaded one.

Since _Subsurface_ matches GPS locations from the Android device and dive
information from the dive computer based on date-time data, automatic
assignment of GPS data to dives is dependent on agreement of the date-time
information between these two devices. Although _Subsurface_ has a wide
range tolerance, it may be unable to identify the appropriate dive if there
is a large difference between the time in the dive computer and that of the
Android device, resulting in no updates.

Similar date-times may not always be possible and there may be many reasons
for this (e.g. time zones), or _Subsurface_ may be unable to decide which is
the correct position for a dive (e.g. on repetitive dives while running
_background service_ there may be several locations that would be included
in the time range that fit not only the first dive, but one or more
subsequent dives as well).  A workaround for this situation to manually edit
the date-time of a dive in the _Subsurface_ Dive List *before* downloading
the GPS data and then to change the date-time back again *after* downloading
GPS data.

[icon="images/icons/info.jpg"]
[NOTE]
TIPS:

_Background service_, being a very powerful tool, may fill the location list
with many unnecessary locations not corresponding to the exact dive point
but reflecting the boat's route.  Currently these locations are difficult to
delete from the server. In some situations it is therefore prudent to clean
up the list on the Android device before sending the dive points to the web
server by simply deleting the inappropriate locations. This might be
necessary, for instance, if one wants to keep the location list clear to see
dives in the web service map display (see above).

It may also make sense to give informative names to the locations sent to
the web server, or at least to use an informative name in the _Name
Template_ setting while running the _background service_, especially on a
dive trip with many dives and dive locations.

[[S_LoadImage]]
=== Adding photographs to dives

Many (if not most) divers take a camera with them and take photographs
during a dive. One would like to associate each photograph with a specific
dive. _Subsurface_ allows one to load photos into a dive. Photos are
superimposed on the dive profile, from where they can be viewed.

==== Loading photos and getting synchronisation between dive computer and camera

Left-lick on a dive or on a group of dives on the dive list. Then
right-click on this dive or group of dives and choose the option _Load
Images_:

image::images/LoadImage1_f20.jpg["FIGURE: Load images option", align="center"]

The system file browser appears. Select the folder and photographs that need
to be loaded into _Subsurface_ and click the _Open_ button.

image::images/LoadImage2_f20.jpg["FIGURE: Load images option", align="center"]

This brings one to the time synchronisation dialog, shown below. The
critical problem is that the time synchronisation is not perfect between the
dive computer used during a dive, and the camera used during that same
dive. These two devices often differ by several minutes. If _Subsurface_ can
achieve synchronisation, then the exact times of photographs can be used to
position photographs on the dive profile.

_Subsurface_ achieves this synchronisation in two ways:

*Manually*: If the user wrote down the exact camera time at the start of a dive, the
difference in time between the two devices can be determined. Actually, as long as the device
settings for time has not been changed in either device, one could write down the times of
both devices after the dive or even at the end of the day. One can then manually set the time
difference in the _Time shift_ dialog. Towards the top of the dialog is a time setting tool
immediately under the heading _Shift times of image(s) by_, evident in figure *A* below.
If the camera time is 7 minutes later than that of the dive computer, set the time setting
tool to a value of 00:07.  Select either the _earlier_ or _later_ radio button.
In the above example, the _earlier_ option is appropriate, since the photos need to be shifted
7 minutes earlier (camera is 7 minutes ahead of dive computer). Ignore any "AM" or "PM" suffix
in that tool. Click the _OK_ button and synchronisation is achieved.

image::images/LoadImage3b_f20.jpg["FIGURE: Synchronisation dialog", align="center"]


*By photograph*: There is a very slick way of achieving synchronisation. If one takes a
photograph of the face of the dive computer showing the time, then _Subsurface_ can obtain
the exact time the photograph was taken, using the metadata that the camera stores within
each photo. In order to do this, use the bottom half of the Time shift_ dialog. If one uses
the bottom part, the top part of the dialog is ignored. Click on
the horizontal bar entitled "_Select image of divecomputer showing time_. This brings up
a file browser with which one can select the photograph of the dive computer. Select the
photograph using the file browser and click on _OK_. This photograph of the dive computer
appears in the bottom panel of the _Shift times_ dialog. Now _Subsurface_ knows exactly
when the photograph has been taken. Now set the date-time dialog to the left of the photo
so that this tool reflects the date and time of the dive computer in the photo. When the
date-time tool has been set, _Subsurface_ knows exactly what the time difference between
camera and dive computer is, and synchronisation is achieved. There is a
photograph with the face of the dive computer and with the date-time tool set to the
date-time on image *B* above.

If the timestamp of a photograph is long before or after the dive, it is not
placed on the dive profile. If the timestamp of the photo is within 30
minutes of the dive, it is shown.

==== Viewing the photos

In order to view the photos added to a dive, activate the _show-photos_
button in the tool bar to the left of the dive profile:

image::images/icons/ShowPhotos_f20.png["FIGURE:Show photos toolbar button", align="left"]

After the images have been loaded, they appear in two places:

 - the _Photos_ tab of the *Dive Notes* panel.
 - as tiny icons (stubs) on the dive profile at the appropriate positions
   reflecting the time each photograph was taken. See below:

image::images/LoadImage4_f20.jpg["FIGURE: Photos on dive profile", align="center"]

If one hovers with the mouse over any of the photo icons, then a thumbnail
photo is shown of the appropriate photo. See the image below:

image::images/LoadImage5_f20.jpg["FIGURE:Thumbnail photo on dive profile", align="center"]

Clicking on the thumbnail brings up a full size photo overlaid on the
_Subsurface_ window. This allows good viewing of the photographs that have
been added (see the image below). Note that the thumbnail has a small
dustbin icon in the bottom right hand corner (see image above). If one
selects the dustbin, the image is removed from the dive. Therefore some care
is required when clicking on a thumbnail. Images can also be deleted using
the _Photos_ tab (see text below).

image::images/LoadImage6_f20.jpg["FIGURE: Full-screen photo on dive profile", align="center"]

==== The _Photos_ tab

Photographs associated with a dive are shown as thumbnails in the _Photos_
tab of the _Dive Notes_ panel. Photos taken in rapid succession during a
dive (therefore sometimes with large overlap on the dive profile) can easily
be accessed in the _Photos_ tab. This tab serves as a tool for individually
accessing the photos of a dive, while the stubs on the dive profile give an
indication of when during a dive a photo was taken. By single-clicking on a
thumbnail in the _Photos_ panel, a photo is selected. By double-clicking a
thumbnail, the full-sized image is shown, overlaying the _Subsurface_
window. A photo can be deleted from the _Photos_ panel by selecting it
(single-click) and then by pressing the _Del_ key on the keyboard. This
removes the photo both from the _Photos_ tab as well as the dive profile.

==== Photos on an external hard disk

Most underwater photographers store their photos on an external drive. If
such a drive can be mapped (almost always the case) the photos can be
directly accessed by _Subsurface_. This facilitates the interaction between
_Subsurface_ and an external repository of photos. When associating a dive
profile with photos from an external drive, the normal procedure of
selection and synchronisation (see text above) is used.  However, after the
external drive has been disconnected, _Subsurface_ cannot access these
photos any more.  If the display of photos is activated (using the toolbox
to the left of the _Dive Profile_), the program only shows a small white dot
where each photo should be on the dive profile.  In addition the _Photos_
tab only shows the file names of the photos. This is normal behaviour.  If,
later, the external drive with the photos is connected again, the photos can
be seen in the normal way.


=== Logging special types of dives

==== Sidemount dives

_Subsurface_ easily handles dives involving more than one
cylinder. Sidemount dive logging involves three steps:

*During the dive, recording cylinder switch events*. Since sidemount diving normally involves two
cylinders with air or with the same gas mixture, _Subsurface_ distinguishes among these different
cylinders. In contrast, most dive computers that allow gas switching only distinguish among different
_gases_ used, not among different _cylinders_ used. This means that when sidemount dives are downloaded
from these dive computers, the events of switching between cylinders with the same gas are not downloaded. This may mean
that one may have to keep a written log of cylinder switch times using a slate, or (if the dive computer
has this facility) marking each cylinder switch with a bookmark that can be retrieved later. Returning
from a dive with the information about cylinder changes is the only tricky part of logging sidemount dives.
*Within _Subsurface_ describe the cylinders used during the dive*. The diver needs to provide the
specifications of the different cylinders, using the *Equipment* tab of the *Dive Info Panel* (see
image below where two 12 litre cylinder were used).
*Indicate cylinder change events on the _Subsurface_ dive profile*. Once the dive log has been imported
from a dive computer into _Subsurface_, the cylinder switch events need to be indicated on the dive profile.
Cylinder changes are recorded by right-clicking at the appropriate point on the dive profile and then
selecting _Add gas change_. A list of the appropriate cylinders is shown with the
currently used cylinder greyed out. In the image below Tank 1 is greyed out, leaving only Tank 2
to be selected. Select the appropriate cylinder. The cylinder change is then indicated on the dive
profile with a cylinder symbol. If the *Tank Bar* is activated using the toolbar to the left of the
profile, then the cylinder change is also indicated on the Tank Bar (see image below). After all
the cylinder change events have been recorded on the dive profile, the correct cylinder pressures
for both cylinders are shown on the dive profile, as inthe image below.

image::images/sidemount1.jpg["FIGURE: Sidemount profile", align="center"]

== Obtaining more information about dives entered into the logbook

=== The *Dive Info* tab (for individual dives)

The Dive Info tab gives some summary information about a particular dive
that has been selected in the *Dive List*. Useful information here includes
the surface interval before the dive, the maximum and mean depths of the
dive, the gas volume consumed, the surface air consumption (SAC) and the
number of oxygen toxicity units (OTU) incurred.

[icon="images/icons/info.jpg"]
[NOTE]
Gas consumption and SAC calculations: _Subsurface_ calculates SAC and Gas
consumption taking in account gas incompressibility, particularly at tank
pressures above 200 bar, making them more accurate.  Users should refer to
xref:SAC_CALCULATION[Appendix D] for more information.

=== The *Extra Data* tab (usually for individual dives)

When using a dive computer, it often reports several data items that cannot
easily be presented in a standardised way because the nature of the
information differs from one dive computer to another. These data often
comprise setup information, metadata about a dive, battery levels, no fly
times, or gradient factors used during the dive. When possible, this
information is presented in the *Extra Data* tab. Below is an image showing
extra data for a dive using a Poseidon rebreather.

image::images/ExtraDataTab_f20.jpg["FIGURE: Extra Data tab", align="center"]

=== The *Stats* tab (for groups of dives)

The Stats tab gives summary statistics for more than one dive, assuming that
more than one dive has been selected in the *Dive List* using the standard
Ctrl-click or Shift-click of the mouse. If only one dive has been selected,
figures pertaining to only that dive are given. This tab shows the number of
dives selected, the total amount of dive time in these dives, as well as the
minimum, maximum and mean for the dive duration, water temperature and
surface air consumption (SAC). It also shows the depth of the shallowest and
deepest dives of those selected.

[[S_DiveProfile]]
=== The *Dive Profile*

image::images/Profile2.jpg["Typical dive profile", align="center"]

Of all the panels in _Subsurface_, the Dive Profile contains the most
detailed information about each dive. The Dive Profile has a *button bar* on
the left hand side that allows control over several display options. The
functions of these buttons are described below. The main item in the Dive
Profile is the graph of dive depth as a function of time. In addition to the
obvious information of the depth it also shows the ascent and descent rates
compared to the recommended speed of going up or down in the water
column. This information is given using different colours:
|====================
|*Colour*|*Descent speed (m/min)*|*Ascent speed (m/min)*
|Red|> 30|> 18
|Orange|18 - 30|9 - 18
|Yellow|9 - 18|4 - 9
|Light green|1.5 - 9|1.5 - 4
|Dark green|< 1.5|< 1.5
|=====================

The profile also includes depth readings for the peaks and troughs in the
graph.  Thus, users should see the depth of the deepest point and other
peaks. Mean depth is marked with a horizontal red line.

[icon="images/icons/scale.jpg"]
[NOTE]
In some cases the dive profile does not fill the whole area of the *Dive
Profile* panel. Clicking the *Scale* button in the toolbar on the left of
the dive profile frequently increases the size of the dive profile to fill
the area of the panel efficiently.

*Water temperature* is displayed with its own blue line with temperature values
placed adjacent to significant changes.

The dive profile can include graphs of the *partial pressures* of O2, N2,
and He during the dive (see figure above) as well as a calculated and dive
computer reported deco ceilings (only visible for deep, long, or repetitive
dives). Partial pressures of oxygen are indicated in green, those of
nitrogen in black, and those of helium in dark red. These partial pressure
graphs are shown below the profile data.

[icon="images/icons/O2.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *oxygen*
during the dive. This is depicted below the dive depth and water temperature
graphs.

[icon="images/icons/N2.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *nitrogen*
during the dive.

[icon="images/icons/He.jpg"]
[NOTE]
Clicking this button allows display of the partial pressure of *helium*
during the dive.  This is only of importance to divers using Trimix,
Helitrox or similar breathing gasses.

The *air consumption* graph displays the tank pressure and its change during
the dive. The air consumption takes depth into account so that even when
manually entering the start and end pressures the graph is not a straight
line.  Similarly to the depth graph the slope of the tank pressure gives the
user information about the momentary SAC rate (Surface Air Consumption) when
using an air integrated dive computer.  Here the colour coding is not
relative to some absolute values but relative to the average normalised air
consumption during the dive. So areas that are red or orange indicate times
of increased normalized air consumption while dark green reflects times when
the diver was using less gas than average.

[icon="images/icons/Heartbutton.png"]
[NOTE]
Clicking on the heart rate button will allow the display of heart rate
information during the dive if the dive computer was attached to a heart
rate sensor.

It is possible to *zoom* into the profile graph. This is done either by using
the scroll wheel / scroll gesture of your mouse or trackpad. By default
_Subsurface_ always shows a profile area large enough for at least 30 minutes
and 30m
 (100ft) – this way short or shallow dives are intuitively recognizable;
something
that free divers clearly won’t care about.

image::images/MeasuringBar.png["FIGURE: Measuring Bar", align="center"]

[icon="images/icons/ruler.jpg"]
[NOTE]
Measurements of *depth or time differences* can be achieved by using the
*ruler button* on the left of the dive profile panel.  The measurement is
done by dragging the red dots to the two points on the dive profile that the
user wishes to measure. Information is then given in the horizontal white
area underneath the two red dots.

[icon="images/icons/ShowPhotos.png"]
[NOTE]
Photographs that have been added to a dive can be shown on the profile by
selecting the *Show-photo* button. The position of a photo on the profile
indicates the exact time when this photo was taken. If this button is not
active, the photos are hidden.


The profile can also include the dive computer reported *ceiling* (more
precisely, the deepest deco stop that the dive computer calculated for each
particular moment in time) as a red overlay on the dive profile. Ascent
ceilings arise when a direct ascent to the surface increases the risk of a
diver suffering from decompression sickness (DCS) and it is necessary to
either ascend slower or to perform decompression stop(s) before ascending to
the surface. Not all dive computers record this information and make it
available for download; for example all of the Suunto dive computers fail to
make this very useful data available to divelog software. _Subsurface_ also
calculates ceilings independently, shown as a green overlay on the dive
profile.  Because of the differences in algorithms used and amount of data
available (and other factors taken into consideration at the time of the
calculation) it is unlikely that ceilings from dive computers and from
_Subsurface_ are the same, even if the same algorithm and _gradient factors_
(see below) are used.  It is also quite common that _Subsurface_ calculates
a ceiling for non-decompression dives when the dive computer stayed in
non-deco mode during the whole dive (represented by the [green]#dark green#
section in the profile at the beginning of this section). This is caused by
the fact that _Subsurface’s_ calculations describe the deco obligation at
each moment during a dive, while dive computers usually take the upcoming
ascent into account. During the ascent some excess nitrogen (and possibly
helium) are already breathed off so even though the diver technically
encountered a ceiling at depth, the dive still does not require an explicit
deco stop. This feature allows dive computers to offer longer non-stop
bottom times.

[icon="images/icons/cceiling.jpg"]
[NOTE]
If the dive computer itself calculates a ceiling and makes it available to
_Subsurface_ during upload of dives, this can be shown as a red area by
checking *Dive computer reported ceiling* button on the Profile Panel.

[icon="images/icons/ceiling1.jpg"]
[NOTE]
If the *Calculated ceiling* button on the Profile Panel is clicked, then a
ceiling, calculated by _Subsurface_, is shown in green if it exists for a
particular dive (*A* in figure below). This setting can be modified in two
ways:

[icon="images/icons/ceiling2.jpg"]
[NOTE]
If, in addition, the *show all tissues* button on the Profile Panel is
clicked, the ceiling is shown for the tissue compartments following the
Bühlmann model (*B* in figure below).

[icon="images/icons/ceiling3.jpg"]
[NOTE]
If, in addition, the *3m increments* button on the Profile Panel is clicked,
then the ceiling is indicated in 3 m increments (*C* in figure below).

image::images/Ceilings2.jpg["Figure: Ceiling with 3m resolution", align="center"]

[icon="images/icons/ShowCylindersButton.jpg"]
[NOTE]
By selecting this icon, the different cylinders used during a dive can be
represented as a coloured bar at the bottom of the *Dive Profile*. In
general oxygen is represented by a green bar, nitrogen with a yellow bar and
helium with a red bar. The image below shows a dive which first uses a
trimix cylinder (red and green), followed by a switch to a nitrox cylinder
(yellow and green) after 23 minutes. Cylinders with air are shown as a light
blue bar.

image::images/ShowCylinders_f20.jpg["Figure: Cylinder use graph", align="center"]


[icon="images/tissues.jpg"]

[NOTE]
Display inert gas tissue pressures relative to ambient inert gas pressure
(horizontal grey line).  Tissue pressures are calculated using the Bühlmann
ZH-L16 algorithm and are displayed as lines ranging from green (faster
tissues) to blue (slower tissues).  The black line, graphed above the
ambient pressure, is the maximum allowable tissue supersaturation (pressure
limit) derived from the gradient factors specified in the *Preferences*. For
divers involved in planned decompression diving, efficient rates of
offgasing are obtained with tissue pressures between the ambient inert gas
pressure (grey line) and the pressure limit (black line). This display is a
representation of the tissue pressures during the whole dive. In contast,
the xref:S_gas_pressure_graph[Gas Pressure Graph] in the *Information Box*
on the *Dive Profile* is an instantaneous reflection of tissue pressures at
the moment in time reflected by the position of the cursor on the dive
profile.

image::images/tissuesGraph.jpg["Figure: Inert gas tissue pressure graph", align="center"]

Gradient Factor settings strongly affect the calculated ceilings and their
depths.  For more information about Gradient factors, see the section on
xref:S_GradientFactors[Gradient Factor Preference settings]. The currently
used gradient factors (e.g. GF 35/75) are shown above the depth profile if
the appropriate toolbar buttons are activated.  *N.B.:* The indicated
gradient factors are NOT the gradient factors in use by the dive computer,
but those used by _Subsurface_ to calculate deco obligations during the
dive. For more information external to this manual see:

 ** http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]

 ** link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]


=== The Dive Profile context menu

The context menu for the Dive Profile is accessed by right-clicking while
the mouse cursor is over the Dive Profile panel. The menu allows the
creation of Bookmarks or Gas Change Event markers or manual CCR set-point
changes other than the ones that might have been imported from a Dive
Computer. Markers are placed against the depth profile line and with the
time of the event set by where the mouse cursor was when the right mouse
button was initially clicked to bring up the menu. Gas Change events involve
a selection of which gas is being switched to, the list of choices being
based on the available gases defined in the Equipment Tab. Set-point change
events open a dialog allowing to choose the next set-point value. As in the
planner, a set-point value of zero indicates the diver is breathing from an
open circuit system while any non-zero value indicates the use of a closed
circuit rebreather (CCR).  By right-clicking while over an existing marker a
menu appears, adding options to allow deletion of the marker or to allow all
markers of that type to be hidden. Hidden events can be restored to view by
selecting Unhide all events from the context menu.

=== The *Information Box*

The Information box displays a large range of information pertaining to the
dive profile. Normally the Information Box is located to the top left of the
*Dive Profile* panel. If the mouse points outside of the *Dive Profile*
panel, then only the top line of the Information Box is visible (see
left-hand part of figure (*A*) below). The Information Box can be moved
around in the *Dive Profile* panel by click-dragging it with the mouse so
that it is not obstructing important detail. The position of the Information
Box is saved and used again during subsequent dive analyses.

image::images/InfoBox2.jpg["Figure: Information Box", align="center"]

The moment the mouse points inside the *Dive Profile* panel, the information
box expands and shows many data items. In this situation, the data reflect
the time point along the dive profile indicated by the mouse cursor (see
right-hand part of figure (*B*) above where the Information Box reflects the
situation at the position of the cursor [arrow] in that image). Therefore,
moving the cursor in the horizontal direction allows the Information Box to
show information for any point along the dive profile.  In this mode, the
Information Box gives extensive statistics about depth, gas and ceiling
characteristics of the particular dive. These include: Time period into the
dive (indicated by a @), depth, cylinder pressure (P), temperature,
ascent/descent rate, surface air consumption (SAC), oxygen partial pressure,
maximum operating depth, equivalent air depth (EAD), equivalent narcotic
depth (END), equivalent air density depth (EADD), decompression requirements
at that instant in time (Deco), time to surface (TTS), the calculated
ceiling, as well as the calculated ceiling for several Bühlmann tissue
compartments.

The user has control over the display of several statistics, represented as
four buttons on the left of the profile panel. These are:

[icon="images/icons/MOD.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *Maximum
Operating Depth (MOD)* of the dive, given the gas mixture used. MOD is
dependent on the oxygen concentration in the breathing gas.  For air (21%
oxygen) it is around 57 m. Below the MOD there is a markedly increased risk
of exposure to the dangers associated with oxygen toxicity.

[icon="images/icons/NDL.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *No-deco
Limit (NDL)* or the *Total Time to Surface (TTS)*. NDL is the time duration
that a diver can continue with a dive, given the present depth, that does
not require decompression (that is, before an ascent ceiling appears). Once
one has exceeded the NDL and decompression is required (that is, there is an
ascent ceiling above the diver, then TTS gives the number of minutes
required before the diver can surface. TTS includes ascent time as well as
decompression time.

[icon="images/icons/SAC.jpg"]
[NOTE]
Clicking this button causes the Information Box to display the *Surface Air
Consumption (SAC)*.  SAC is an indication of the surface-normalised
respiration rate of a diver. The value of SAC is less than the real
respiration rate because a diver at 10m uses breathing gas at a rate roughly
double that of the equivalent rate at the surface. SAC gives an indication
of breathing gas consumption rate independent of the depth of the dive so
that the respiratory rates of different dives can be compared. The units for
SAC is litres/min or cub ft/min.

[icon="images/icons/EAD.jpg"]
[NOTE]
Clicking this button displays the *Equivalent Air Depth (EAD)* for nitrox
dives as well as the *Equivalent Narcotic Depth (END)* for trimix
dives. These are numbers of importance to divers who use breathing gases
other than air. Their values are dependent on the composition of the
breathing gas.  The EAD is the depth of a hypothetical air dive that has the
same partial pressure of nitrogen as the current depth of the nitrox dive at
hand. A nitrox dive leads to the same decompression obligation as an air
dive to the depth equalling the EAD. The END is the depth of a hypothetical
air dive that has the same sum of partial pressures of the narcotic gases
nitrogen and oxygen as the current trimix dive. A trimix diver can expect
the same narcotic effect as a diver breathing air diving at a depth
equalling the END.

Figure (*B*) above shows an information box with a nearly complete set of
data.

[[S_gas_pressure_graph]]
==== The Gas Pressure Bar Graph

On the left of the *Information Box* is a vertical bar graph indicating the
pressures of the nitrogen (and other inert gases, e.g. helium, if
applicable) that the diver was inhaling _at a particular instant during the
dive_, indicated by the position of the cursor on the *Dive Profile*. The
drawing on the left below indicates the meaning of the different parts of
the Gas Pressure Bar Graph.

image::images/GasPressureBarGraph.jpg["FIGURE:Gas Pressure bar Graph", align="center"]

The light green area indicates the total gas, with the top margin of the
light green area indicating the total gas pressure inhaled by the diver and
measured from the bottom of the graph to the top of the light green
area. This pressure has a _relative_ value in the graph and does not
indicate absolute pressure.

The horizontal black line underneath the light green margin indicates the
equilibrium pressure of the inert gases inhaled by the diver, usually
nitrogen. In the case of trimix, it is the pressures of nitrogen and helium
combined. In this example, the user is diving with EAN32, so the inert gas
pressure is 68% of the distance from the bottom of the graph to the total
gas pressure value.

The dark green area at the bottom of the graph represents the pressures of
inert gas in each of the 16 tissue compartments, following the Bühlmann
algorithm, the fast tissues being on the left hand side.

The top black horizontal line indicates the gradient factor that applies to
the depth of the diver at the particular point on the *Dive Profile*. The
appropriate gradient factor is an interpolation between the FGLow and GFHigh
values specified in the Graph tab of the *Preferences Panel* of
*Subsurface*.

The bottom margin of the red area in the graph indicates the Bühlman-derived
M-value, that is the pressure value of inert gases at which bubble formation
is expected to be severe, resulting in decompression sickness.

These five values are indicated on the left in the graph above. The way the
Gas Pressure Bar Graph changes during a dive is indicated on the right hand
side of the above figure for a diver using EAN32.

Graph *A* indicates the situation at the start of a dive with diver at the
surface. The pressures in all the tissue compartments are still at the
equilibrium pressure because no diving has taken place.

Graph *B* indicates the situation after a descent to 30 meters. Few of the
tissue compartments have had time to respond to the descent, their gas
pressures being far below the equilibrium gas pressure.

Graph *C* represents the pressures after 30 minutes at 30 m. The fast
compartments have attained equilibrium (i.e. they have reached the hight of
the black line indicating the equilibrium pressure). The slower compartments
(towards the right) have not reached equilibrium and are in the process of
slowly increasing in pressure.

Graph *D* shows the pressures after ascent to a depth of 4.5 meters. Since,
during ascent, the total inhaled gas pressure has decreased strongly from 4
bar to 1.45 bar, the pressures in the different tissue compartments now
exceed that of the total gas pressure and approaches the gradient factor
value (i.e.  the top black horizontal line). Further ascent will result in
exceeding the gradient factor value (GFHigh), endangering the diver.

Graph *E* indicates the situation after remaining at 4.5 meters for 10
minutes. The fast compartments have decreased in pressure. As expected, the
pressures in the slow compartments have not changed much.  The pressures in
the fast compartments do not approach the GFHigh value any more and the
diver is safer than in the situation indicated in graph *D*.



== Organising the logbook (Manipulating groups of dives)

=== The Dive List context menu

Many actions within _Subsurface_ are dependent on a context menu used mostly
to manipulate groups of dives. The context menu is found by selecting a dive
or a group of dives and then right-clicking.

image::images/ContextMenu.jpg["Figure: Context Menu", align="center"]

The context menu is used in many manipulations described below.

==== Customising the information showed in the *Dive List* panel

image::images/DiveListOptions.jpg["Example: Dive list info options", align="center"]

The default information in the *Dive List* includes, for each dive,
Dive_number, Date, Rating, Dive_depth, Dive_duration and Dive_location. This
information can be controlled and changed by right-clicking on the header
bar of the *Dive List*. For instance, a right-click on the 'Date' header
brings up a list of items that can be shown in the dive list (see
above). Select an item to be shown in the *Dive List* or to be deleted from
the dive list, and the list is immediately updated accordingly. Preferences
for information shown in the *Dive List* is saved and used when _Subsurface_
is re-opened.

==== Selecting dives from a particular dive site

Many divers have long dive lists and it may be difficult to locate all the
dives at a particular site.  By pressing _Ctl-F_ on the keyboard, a text box
is opened at the top left hand of the *Dive List*.  Type the name of a dive
site in this text box and the *Dive List* is immediately filtered to show
only the dives for that site.

[[S_Renumber]]
=== Renumbering the dives

Dives are normally numbered incrementally from non-recent dives (low
sequence numbers) to recent dives (having the highest sequence numbers). The
numbering of the dives is not always consistent. For instance, when
non-recent dives are added to the dive list the numbering does not
automatically follow on because of the dives that are more recent in
date/time than the newly-added dive with an older date/time. Therefore, one
may sometimes need to renumber the dives.  This is performed by selecting
(from the Main Menu) _Log -> Renumber_. Users are given a choice with
respect to the lowest sequence number to be used.  Completing this operation
results in new sequence numbers (based on date/time)  for the dives in the
*Dive List* panel.

[[S_Group]]
=== Grouping dives into trips and manipulating trips

For regular divers, the dive list can rapidly become very long. _Subsurface_
can group dives into _trips_. It performs this by grouping dives that have
date/times that are not separated in time by more than two days, thus
creating a single heading for each diving trip represented in the dive
log. Below is an ungrouped dive list (*A*, on the left) as well as the
corresponding grouped dive list comprising five dive trips (*B*, on the
right):

image::images/Group2.jpg["Figure: Grouping dives", align="center"]

Grouping into trips allows a rapid way of accessing individual dives without
having to scan a long lists of dives. In order to group the dives in a dive
list, (from the Main Menu) users must select _Log -> Autogroup_. The *Dive
List* panel now shows only the titles for the trips.

==== Editing the title and associated information for a particular trip

Normally, in the dive list, minimal information is included in the trip
title.  More information about a trip can be added by selecting its trip
title from the *Dive List*. This shows a *Trip Notes* tab in the *Dive
Notes* panel. Here users can add or edit information about the date/time,
the trip location and any other general comments about the trip as a whole
(e.g. the dive company that was dived with, the general weather and surface
conditions during the trip, etc.).  After entering this information, users
should select *Save* from the buttons at the top right of the *Trip Notes*
tab. The trip title in the *Dive List* panel should now reflect some of the
edited information.

==== Viewing the dives during a particular trip

Once the dives have been grouped into trips, users can expand one or more
trips by clicking the arrow-head on the left of each trip title. This
expands the selected trip, revealing the individual dives performed during
the trip.

==== Collapsing or expanding dive information for different trips

If a user right-clicks after selecting a particular trip in the dive list,
the resulting context menu allows several possibilities to expand or
collapse dives within trips. This includes expanding all trips, collapsing
all trips and collapsing all trips except the selected one.

==== Merging dives from more than one trip into a single trip

By right-clicking on a selected trip title in the *Dive List* panel, a
context menu shows up that allows the merging of trips by either merging of
the selected trip with the trip below or with the trip above.

==== Splitting a single trip into more than one trip

If a trip includes five dives, the user can split this trip into two trips
(trip 1: top 3 dives; trip 2: bottom 2 dives) by selecting and
right-clicking the top three dives. The resulting context menu allows the
user to create a new trip by choosing the option *Create new trip
above*. The top three dives are then grouped into a separate trip. The
figures below shows the selection and context menu on the left (A) and the
completed action on the right (B):

image::images/SplitDive3a.jpg["FIGURE: Split a trip into 2 trips", align="center"]

=== Manipulating single dives

==== Delete a dive from the dive log

Dives can be permanently deleted from the dive log by selecting and
right-clicking them to bring up the context menu, and then selecting *Delete
dive(s)*. Typically this would apply to a case where a user wishes to delete
workshop calibration dives of the dive computer or dives of extremely short
duration.

==== Unlink a dive from a trip

Users can unlink dives from the trip to which they belong. In order to do
this, select and right-click the relevant dives to bring up the context
menu. Then select the option *Remove dive(s)  from trip*. The dive(s) now
appear immediately above the trip to which they belonged.

==== Add a dive to the trip immediately above

Selected dives can be moved from the trip to which they belong and placed
within the trip immediately above the currently active trip. To do this,
select and right-click the dive(s) to bring up the context menu, and then
select *Add dive(s) to trip immediately above*.

==== Shift the start time of dive(s)

Sometimes it is necessary to adjust the start time of a dive. This may apply
to situations where dives are performed in different time zones or when the
dive computer has an erroneous time. In order to do this, user must select
and right-click the dive(s) to be adjusted. This action brings up the
context menu on which the *Shift times* option should be selected. User must
then specify the time (in hours and minutes) by which the dives should be
adjusted and click on the option indicating whether the time adjustment
should be forwards or backwards.

==== Merge dives into a single dive

Sometimes a dive is briefly interrupted, e.g. if a diver returns to the
surface for a few minutes, resulting in two or more dives being recorded by
the dive computer and appearing as different dives in the *Dive List*
panel. Users can merge these dives onto a single dive by selecting the
appropriate dives, right-clicking them to bring up the context menu and then
selecting *Merge selected dives*. It may be necessary to edit the dive
information in the *Dive Notes* panel to reflect events or conditions that
apply to the merged dive. The figure below shows the depth profile of two
such dives that were merged:

image::images/MergedDive.png["Example: Merged dive", align="center"]

[[S_Filter]]
=== Filtering the dive list

The dives in the *Dive List* panel can be filtered, that is, one can select
only some of the dives based on their attributes, e.g. dive tags, dive site,
dive master, buddy or protective clothing. For instance, filtering allows
one to list the deep dives at a particular dive site, or otherwise the cave
dives with a particular buddy.

To open the filter, select _Log -> Filter divelist_ from the main menu. This
opens the _Filter Panel_ at the top of the _Subsurface_ window. Three icons
are located at the top right hand of the filter panel. The _Filter Panel_
can be reset (i.e. all current filters cleared) by selecting the *+*. The
_Filter Panel_ may also be minimised by selecting the middle icon. When
minimised, only these three icons are shown.  The panel can be maximised by
clicking the icon that minimised the panel. The filter may also be reset and
closed by selecting the button with the flag.  An example of the _Filter
Panel_ is shown in the figure below.


image::images/Filterpanel.jpg["Figure: Filter panel", align="center"]


Four filter criteria may be used to filter the dive list: dive tags, person
(buddy / dive master), dive site and dive suit, each of which is represented
by a check list with check boxes. Above each check list is a second-level
filter tool, allowing the listing of only some of the attributes within that
check list. For instance, typing "_ca_" in the filter textbox above the tags
check list results in the tags check list being reduced to "_cave_" and
"_cavern_". Filtering of the check list enables the rapid finding of search
terms for filtering the dive list.

To activate filtering of the dive list, the check box of at least one item
in one of the four check lists needs to be checked. The dive list is then
shortened to include only the dives that pertain to the selection criteria
specified in the check lists.  The four check lists work as a filter with
_AND_ operators, Subsurface filters therefore for _cave_ as a tag AND _Joe
Smith_ as a buddy; but the filters within a category are inclusive -
filtering for _cave_ and _boat_ shows those dives that have either one or
both of these tags.

[[S_ExportLog]]
== Exporting the dive log or parts of the dive log

The export function can be reached by selecting _File -> Export_, which
brings up the Export dialog. This dialog always gives two options: save ALL
dives, or save only the dives selected in *Dive List* panel of
_Subsurface_. Click the appropriate radio button (see images below).

image::images/Export.jpg["Figure: Export dialog", align="center"]

A dive log or part of it can be saved in three formats:

* _Subsurface XML_ format. This is the native format used by _Subsurface_.

Universal Dive Data Format (_UDDF_). Refer to _http://uddf.org_ for more
information.  UDDF is a generic format that enables communication among many
dive computers and computer programs.

_Divelogs.de_, an Internet-based dive log repository. In order to upload to
_Divelogs.de_, one needs a user-ID as well as a password for
_Divelogs.de_. Log into _http://en.divelogs.de_ and subscribe to this
service in order to upload dive log data from _Subsurface_.

_CSV_ format, that includes the most critical information of the dive
profile. Included information of a dive is: dive number, date, time,
duration, depth, temperature and pressure.

_Worldmap_ format, an HTML file with a world map upon which each dive and
some information about it are indicated. This map is not editable.

_HTML_ format, in which the dive(s) are stored in HTML files, readable with
an Internet browser. Most modern web browsers are supported, but JavaScript
must be enabled. This generated HTML file is not intended to be edited by
the users.  The HTML dive log contains most of the information and also
contains a search option to search the dive log. HTML export is specified on
the second tab of the Export dialog (image *B* above).

* _General Settings_, under the HTML tab, provides the following options:

** Subsurface Numbers: if this option is checked, the dive(s) are exported with the
numbers associated with them in Subsurface, Otherwise the dive(s) will be numbered
starting from 1.
** Export Yearly Statistics: if this option is checked, a yearly statistics table will
be attached with the HTML exports.
** Export List only: a list of dives will only be exported and the detailed dive
information will not be available.

Under _Style Options_ some style-related options are available like font
size and theme.

Export to other formats can be achieved through third party facilities, for
instance _www.divelogs.de_.

[[S_Cloud_access]]
== Keeping a _Subsurface_ dive log in the Cloud

For each diver, dive log information is highly important. Not only is it a
record of diving activities for one's own pleasure, but it is important
information required for admission to further training courses or
(sometimes) even diving sites. The security of the dive log is therefore
critical. In order to have a dive log that is resistant to failure of a home
computer hard drive, loss or theft of equipment, the Cloud is an obvious
solution. This also has the added benefit that one can access one's dive log
from anywhere in the world without having to carry it with oneself. For this
reason, facilities such as _divelogs.de_ and _Diving Log_ offer facilities
to store dive log information on the Internet. Although _Subsurface_ does
not offer integrated Cloud storage of dive logs, it is simple to achieve
this using several of the existing facilities on the Internet.

For instance http://www.dropbox.com/[_Dropbox_] offers a free application
that allows files on the Dropbox servers to be seen as a local folder on
one's desktop computer.

image::images/Cloud.jpg["FIGURE: Dropbox folder", align="center"]

The _Dropbox_ program creates a copy of the _Dropbox_ Internet Cloud content
on one's desktop computer. When the computer is connected to the Internet,
the Internet content is automatically updated. Therefore both the _Open_ and
_Save_ of dive logs are done using the local copy of the dive log in the
local _Dropbox_ folder, so there's no need for a direct internet
connection. If the local copy is modified, e.g. by adding a dive, the remote
copy in the _Dropbox_ server in the Cloud will be automatically updated
whenever Internet access is available.

In this way a dive log in one's _Dropbox_ folder can be accessed seamlessly
from the Internet and can be accessed from any place with Internet
access. Currently there are no costs involved for this service. Dropbox
(Windows, Mac and Linux) can be installed by accessing the
http://www.dropbox.com/install[_Install Page on the Dropbox website_]
Alternatively one can use _Dropbox_ as a mechanism to backup one's dive
log. To Store a dive log in the Cloud, select _File->Save as_ from the
_Subsurface_ main menu, navigate to the _Dropbox_ folder and select the
_Save_ button. To access the dive log in the Cloud, select _File->Open
Logbook_ from the _Subsurface_ main menu and navigate to the dive log file
in the _Dropbox_ folder and select the _Open_ button.

Several paid services exist on the Internet (e.g. Google, Amazon) where the
same process could be used for the Cloud-based storage of dive logs.


[[S_PrintDivelog]]
== Printing a dive log

_Subsurface_ provides a simple interface to print a whole dive log or only a
few selected dives, including dive profiles and other contextual
information.

Before printing, two decisions are required:

Should the whole dive log be printed or only part of it? If only part of the
dive log is required, then the user must select the required dives from the
*Dive List* panel.
What gas partial pressure information is required on the dive profile? Users
should select the appropriate toggle-buttons on the button bar to the left
of the Dive Profile panel.

Now the print options should be selected to match the user's needs. To do
this, user should select _File->Print_ from the Main menu. The following
dialogue appears (see the image on the left [A], below).

image::images/PrintDiveLog.jpg["FIGURE: Print dialogue", align="center"]

Under _Print type_ users need to select one of three options:

- Print the complete Dive List: to do this, _Table Print_ should be selected.
Print the selected dives (dive profiles and all other information) at 6
dives per printed page: to do this, users should select _6 dives per page_.
Print the selected dives (dive profiles and all other information) at 2
dives per printed page: to do this, users should select _2 dives per page_.
Print the selected dives (dive profiles and all other information) at 1 dive
per printed page: to do this, users should select _1 dive per page_.

Under _Print options_ users need to select:

Printing only the dives that have been selected from the dive list prior to
activating the print dialogue, achieved by checking the box _Print only
selected dives_.
- Printing in colour, achieved by checking the box with _Print in colour_.

The _Ordering_ affects the layout of the page (or part of it) for each
dive.  The dive profile could be printed at the top of each dive, with the
textual information underneath, or it could be printed with the textual
information at the top with the dive profile underneath. Users should select
the appropriate option in the print dialogue. See the image below which has
a layout with text below the dive profile.

Users can _Preview_ the printed page by selecting the _Preview_ button on
the dialogue. After preview, changes to the options in the print dialogue
can be made, resulting in a layout that fits personal taste.

Next, select the _Print_ button in the dialogue. This activates the regular
print dialogue used by the user operating system (image [*B*] in the middle,
above), allowing them to choose a printer and to set its properties (image
[*C*] on the right, above).  It is important to set the print resolution of
the printer to an appropriate value by changing the printer
properties. Finally, one can print the dives. Below is a (rather small)
example of the output for one particular page.

image::images/Printpreview.jpg["FIGURE: Print preview page", align="center"]


[[S_Preferences]]
== Setting user _Preferences_ for _Subsurface_

There are several settings within _Subsurface_ that the user can
specify. These are found when selecting _File->Preferences_. The settings
are performed in five groups: *Defaults*, *Units*, *Graph*, *Language* and
*Network*. All five sections operate on the same principles: the user must
specify the settings that are to be changed, then these changes are saved
using the *Apply* button. After applying all the new settings users can then
leave the settings panel by selecting *OK*.

=== Defaults

There are several settings in the *Defaults* panel:

image::images/Pref1.jpg["FIGURE: Preferences defaults page", align="center"]

  ** *Lists and tables*: Here one can specify the font type and font size of the
*Dive Table* panel. By decreasing the font size of the *Dive Table*, users can see more dives on a screen.

  ** *Dives*: For the _Default Dive File_ one need to specify the directory and
file name of one's
electronic dive log book. This is a file with filename extension .xml. When
launched, _Subsurface_ will automatically load the specified dive log book.

  ** *Display invalid*:  Dives can be marked as invalid (when a user wishes to hide
dives that he/she don't consider valid dives, e.g. pool dives, but still want to
keep them in the dive log). This controls whether those dives are displayed in
the dive list.

  ** *Default cylinder*: Here users can specify the default cylinder listed in
the *Equipment* tab of the *Dive Notes* panel.

  ** *Animations*: Some actions in showing the dive profile are performed using
animations. For instance, the axis values for depth and time change from dive to
dive. When viewing a different dive, these changes in axis characteristics do not
happen instantaneously, but are animated. The _Speed_ of animations can be controlled
by setting this slider
with faster animation speed to the left, with a 0 value representing no animation
at all.

 ** *Subsurface web service*: When one subscribes to the <<S_Companion,Subsurface web service>>, a very
long and hard-to-remember userID is issued. This is the place to save that userID. By
checking the option _Save User ID locally?_, one ensures that a local copy of that userID
is saved.

 ** *Clear all settings*: As indicated in the button below this heading, all settings are
cleared and set to default values.

=== Units
image::images/Pref2.jpg["FIGURE: Preferences Units page", align="center"]

Here user can choose between metric and imperial units of depth, pressure,
volume, temperature and mass. By selecting the Metric or Imperial radio
button at the top, users can specify that all units are in the chosen
measurement system.  Alternatively, if one selects the *Personalise* radio
button, units can be selected independently, with some units in the metric
system and others in imperial.

=== Graph
image::images/Pref3.jpg["FIGURE: Preferences Graph page", align="center"]

[[S_GradientFactors]]
This panel allows two type of selections:

*Show*: Here users can specify the amount of information shown as part of
the dive profile:
** Thresholds: _Subsurface_ can display the nitrogen, oxygen and the helium partial pressures during
the dive. These are enabled using the toolbar on the left hand side of the *Dive Profile*
panel. For each of these graphs users can specify a threshold value on the right-hand side of the
Preferences panel. If any of the graphs go above this threshold level, the graph is
highlighted in red, indicating that the threshold has been exceeded.

** _Draw dive computer reported ceiling red_: This checkbox allows exactly what it says.
Not all dive computers report ceiling values. If the dive computer does report it, it may differ
from the ceilings calculated by _Subsurface_. This is because of the different algorithms and gradient factors available for calculating ceilings, as well as the dynamic way that a
dive computer can calculate ceilings during a dive.

** _Show unused cylinders in Equipment Tab_: This checkbox allows display of information about unused cylinders when viewing the *Equipment Tab*. Conversely, if this box is not checked, and any cylinders entered using the *Equipment Tab* are not used (e.g. there was no gas switch to such a cylinder), then these cylinders are omitted from that list.

** _Show average depth_: Activating this checkbox causes _Subsurface_ to draw a red line across
the dive profile, indicating the mean depth of the dive.

* *Misc*:

** Gradient Factors:* Here users can set the _gradient factors_ used while diving. GF_Low is
the gradient factor at depth and GF_High is used just below the surface.
At intermediate depths gradient factors between GF_Low and GF_High are used.
Gradient factors add conservatism to the nitrogen exposure during a dive, in a
similar way that many dive computers have a conservatism setting. The lower
the value of a gradient factor, the more conservative the calculations are with
respect to nitrogen loading and the deeper the ascent ceilings are. Gradient
factors of 20/60 are considered conservative and values of 60/90 are considered
harsh. Checking *GFLow at max depth* box causes GF_Low to be used at the
deepest depth of a dive. If this box is not checked, GF_Low is applied at
all depths deeper than the first deco stop. For more information see:

 ** http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]

 ** link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]

=== Language
Choose a language that _Subsurface_ will use.

image::images/Pref4.jpg["FIGURE: Preferences Language page", align="center"]

A checkbox allows one to use the _System Default_ language which in most
cases will be the correct setting; with this _Subsurface_ simply runs in the
same language / country settings as the underlying OS. If this is for some
reason undesirable users can uncheck this checkbox and pick a language /
country combination from the list of included localizations. The _Filter_
text box allows one to list similar languages. For instance there are
several system variants of English or French. This particular preference
requires a restart of _Subsurface_ to take effect.

=== Network
This panel facilitates communication between _Subsurface_ and data sources
on the Internet.

image::images/Pref5.jpg["FIGURE: Preferences Network page", align="center"]

This is important, for instance, when _Subsurface_ needs to communicate with
Internet services such as the <<S_Companion,_Subsurface Companion app_>> or
data export/import from _Divelogs.de_. These Internet requirements are
determined by one's type of connection to the Internet and by the Internet
Service Provider (ISP) used.  One's ISP should provide the appropriate
information.  If a proxy server is used for Internet access, the appropriate
information needs to be provided here. The type of proxy needs to be
selected from the dropdown list.  after which the IP address of the host and
the appropriate port number should be provided. If the proxy server uses
authentication, the appropriate userID and password also needs to be
provided so that _Subsurface_ can automatically pass through the proxy
server to access the Internet.

[[S_DivePlanner]]
== The _Subsurface_ dive planner
Dive planning is an advanced feature of _Subsurface_, accessible by
selecting _Log -> Plan Dive_ from the main menu. It allows calculation of
nitrogen load during a dive by using the Bühlmann ZH-L16 algorithm with the
addition of gradient factors as implemented by Erik Baker.

****
[icon="images/icons/warning2.png"]
[WARNING]

The _Subsurface_ dive planner IS CURRENTLY EXPERIMENTAL and assumes the user
is already familiar with the _Subsurface_ user interface. It is explicitly
used under the following conditions:

The user is conversant with dive planning and has the necessary training to
perform dive planning.
- The user plans dives within his/her certification limits.
Dive planning makes large assumptions about the characteristics of the
_average person_ and cannot compensate for individual physiology or health
or personal history or life style characteristics.
- The safety of a dive plan depends heavily on the way in which the planner is
  used.
- The user is familiar with the user interface of _Subsurface_.
A user who is not absolutely sure about any of the above requirements should
not use this feature.
****

=== The _Subsurface_ dive planner screen

Like the _Subsurface_ dive log, the planner screen is divided into several
sections (see image below). The *setup* parameters for a dive are entered
into the several sections on the left hand side of the screen.  The setup is
divided into several sections: Available Gases, Rates, Planning, Gas Options
and Dive Notes.

At the top right hand is a green *design panel* upon which the profile of
the dive can be manipulated directly by dragging and clicking as explained
below. This feature makes the _Subsurface_ dive planner unique in ease of
use.

At the bottom right is a text panel with a heading of _Dive Plan
Details_. This is where the details of the dive plan are provided in a way
that can easily be copied to other software. This is also where any warning
messages about the dive plan are printed.

image::images/PlannerWindow1.jpg["FIGURE: Dive planner startup window", align="center"]


=== Initiating dive planning

The dive planner comprises two parts: *constructing a dive plan* and
*evaluating* that dive plan. To perform dive planning, perform these steps:

Clear the existing dive log by creating a new planning log. This is achieved
by selecting _File -> New logbook_ from the main menu. This way, dive plans
are kept separate from the existing dive log of completed dives.

In the top left-hand area of the screen, ensure that the constant dive
parameters are appropriate. These are: Start date and time of the dive,
Atmospheric Pressure and Altitude above sea level of the dive site. The
atmospheric pressure can also be entered as an altitude in metres, assuming
an atmospheric pressure of 1.013 bar.

In the table labelled _Available Gases_, add the information of the
cylinders to be used as well as the gas composition within that
cylinder. This is done in a similar way as for <<S_CylinderData,providing
cylinder data for dive logs>>. Choose the cylinder type by double clicking
the cylinder type and using the dropdown list, then specify the work
pressure of this cylinder. By leaving the oxygen concentration (O2%) filed
empty, the dive gas is assumed to be air. Otherwise enter the oxygen and/or
helium concentration in the boxes provided in this dialogue. Add additional
cylinders by using the "+" icon to the top righthand of the dialogue.

The dialogue indicating _Dive Planner Points_ is usually not used at this
stage of the dive planning.

=== Managing nitrogen, oxygen and gas consumption

The planning is performed in three stages:

*a) Nitrogen management*: This is performed by specifying the rates for descent and ascent,
as well as the gradient factors (GFLow and GFHigh) under the headings _Rates_ and _Planning_
to the bottom left of the planning screen. Initially, the GFHigh and GFLow values in the _Preferences_
panel of _Subsurface_ is used. If these are changed within the planner (see _Gas Options_ within
the planner), the new values are
used without changing the original specifications in the _Preferences_. Gradient Factor settings strongly affect the calculated ceilings and their depths.
A very low GFLow value brings about decompression stops early on during the dive.
 ** For more information about Gradient factors, see the section on xref:S_GradientFactors[Gradient Factor Preference settings].
For more information external to this manual see:

 *** link:http://www.tek-dive.com/portal/upload/M-Values.pdf[Understanding M-values by Erik Baker, _Immersed_ Vol. 3, No. 3.]
 *** link:http://www.rebreatherworld.com/general-and-new-to-rebreather-articles/5037-gradient-factors-for-dummies.html[Gradient factors for dummies, by Kevin Watts]
 *** link:http://www.amazon.com/Deco-Divers-Decompression-Theory-Physiology/dp/1905492073/ref=sr_1_1?s=books&ie=UTF8&qid=1403932320&sr=1-1&keywords=deco+for+divers[_Deco for Divers_, by Mark Powell (2008). Aquapress] Southend-on-Sea, UK. ISBN 10: 1-905492-07-3.
An excellent non-technical review.

 ** The ascent rate is critical for nitrogen off-gassing at the end of the dive and is specified
for several depth ranges, utilising the average (or mean) depth as a yardstick. The mean depth
of the dive plan is indicated on the dive profile in the green panel of the dive planner. Ascent rates
at deeper levels are often in the range of 8-12 m/min, while ascent rates near the surface are
often in the range of 4-9 m/min. The descent rate is also specified. If the option _Drop to first depth_
is activated, then the descent phase of the planned dive will be at the maximal descent rate specified
in the _Rates_ section of the dive setup.


*b) Oxygen management*: In the *Gas Options* part of the dive specification, the maximum partial
pressure for oxygen needs to be specified for the
bottom part of the dive (_bottom po2_) as well as for the decompression part of the dive (_deco po2_).
The most commonly
used values are 1.4 bar for the bottom part of the dive and 1.6 bar for any decompression
stages. Normally, a partial pressure of 1.6 bar is not exceeded. PO2 settings and the depth at which switching to a gas takes place can also be edited in the
_Available Gases_ dialog. Normally the planner decides on switching to a new gas when, during
ascent, the partial pressure of the new gas has decreased to 1.6 bar.


*c) Gas management*: One needs keep within the limits of the amount of gas contained in the dive
cylinder(s), allowing for an appropriate margin for safe return to the surface, possibly
sharing with a buddy. Under the _Gas Options_ heading, specify the best (but conservative) estimate
of your surface-equivalent air consumption (SAC, also termed RMV) in
litres/min (for the time being, only SI units are supported).  Specify the SAC during the
bottom part of the dive (_bottom SAC_) as well as during the decompression or safety stops of the
dive (_deco SAC_). Values of 20-30 l/min are common. For good gas management, a thumbsuck guess
is not sufficient and one needs to
monitor one's gas consumption on a regular basis, dependent on different dive conditions and/or equipment.
The planner will calculate the total volume of gas used during the dive and will issue a warning
if one exceeds the total amount of gas available. Good practice demands that one does not dive to
the limit of the gas supply but that an appropriate reserve is kept for unforeseen circumstances.
For technical diving, this reserve can be up to 66% of the total available gas.

Now (at last) one can start the detailed time-depth planning of the
dive. _Subsurface_ offers a unique graphical interface for performing this
part of the planning. The mechanics of doing this is similar to
hand-entering a dive profile in the dive log part of _Subsurface_. Upon
activating the planner, a default dive of depth 15 m for 40 min is offered
in the green design surface to the top right hand of the screen. The white
dots (waypoints) on the profile can be dragged with a mouse. Create more
waypoints by double-clicking on the profile line and ensuring that the
profile reflects the intended dive. Drag the waypoints to represent the
depth and duration of the dive.  If any of the management limits (for
nitrogen, oxygen or gas) is exceeded, the surface above the dive profile
changes from BLUE to RED.

Each waypoint on the dive profile creates a _Dive Planner Point_ in the
table on the left of the dive planner panel. Ensure that the _Used Gas_
value in each row of that table corresponds to one of the gas mixtures
specified in the table with _Available Gases_ immediately above the Dive
Planner Points. Add new waypoints until the main features of the dive have
been completed, e.g. the bottom time segment and deep stops (if these are
implemented). Leave the remaining waypoints on the ascent to
_Subsurface_. In most cases _Subsurface_ computes additional way points in
order to fulfil decompression requirements for that dive. A waypoint can be
moved by selecting that waypoint and by using the arrow keys.  The waypoints
listed in the _Dive Planner Points_ dialogue can be edited by hand in order
to obtain a precise presentation of the dive plan. In fact, one can create
the whole dive profile by editing the _Dive Planner Points_ dialog.

Indicate any changes in gas cylinder used by indicating gas changes as
explained in the section <<S_CreateProfile,hand-creating a dive
profile>>. These changes should reflect the cylinders and gas compositions
defined in the table with _Available Gases_.  If two or more gases are used,
automatic gas switches will be suggested during the ascent to the
surface. However, these changes can be deleted by right-clicking the gas
change and by manually creating a gas change by right-clicking on the
appropriate waypoint.

A non-zero value in the "CC set point" column of the table of dive planner
points indicates a valid setpoint for oxygen partial pressure and that the
segment is dived using a closed circuit rebreather (CCR). If the last
manually entered segment is a CCR segment, the decompression phase is
computed assuming the diver uses a CCR with the specified set-point. If the
last segment (however short) is on open circuit (OC, indicated by a zero
set-point) the decompression is computed in OC mode. The planner only
considers gas changes in OC mode.

Below is an example of a dive plan to 45m using EAN26, followed by an ascent
using EAN50 and using the settings as described above.

image::images/DivePlanner2.jpg["FIGURE: Planning a dive: setup", align="center"]

Once the above has been completed, one can save it by clicking the _Save_
button towards the bottom left of the green design panel. The saved dive
plan will appear in the *Dive List* panel of _Subsurface_.

=== The dive plan details

On the bottom right of the dive planner, under _Dive Plan Details_, the
exact details of the dive plan are provided. These details may be modified
by checking any of the options under the _Dive Notes_ section of the dive
planner, immediately to the left of the _Dive Plan Details_. If a _Verbatim
diveplan_ is requested, a detailed sentence-level explanation of the dive
plan is given. If any of the management specifications have been exceeded
during the planning, a warning message is printed underneath the dive plan
information.

If the option _Display segment duration_ is checked, then the duration of
each depth level is indicated in the _Dive Plan Details_. This duration
INCLUDES the transition time to get to that level. However, if the _Display
transition in deco_ option is checked, the transitions are shown separately
from the segment durations at a particular level.

[[S_Replan]]
=== Modifying an existing dive plan

Normally, when a dive plan has been saved, it is accessible from the *Dive
List*, like any other dive log. Within the *Dive List* there is not a way to
change a saved dive plan.  To perform changes to a dive plan, select it on
the *Dive List*. Then, in the main menu, select _Log -> Re-plan dive_. This
will open the selected dive plan within the dive planner, allowing changes
to be made and saved as usual.

In addition there is the option "Save new". This keeps the original planned
dive and adds a (possibly modified) copy to the dive list. If that copy is
saved with the same start time as the original, the two dives are considered
two versions of the same dive and do not influence other each during
decompression calculation (see next section).

=== Planning for repetitive dives

Repetitive dives can easily be planned if the dates and start times of the
repetitive dive set is specified appropriately in the top left-hand _Start
Time_ field. _Subsurface_ calculates the gas loading figures correctly and
the effect of the first dive is evaluated on later dives.

If one has just completed a long/deep dive and is planning another dive,
then highlight, in the *Dive List*, the dive that has just been completed
and then activate the planner. Depending on the start time of the planned
dive, the planner takes into account the gas loading incurred during the
completed dive and allows planning within these limitations.

If only a few standard configurations are used (e.g. in GUE), then a
template dive can be created conforming to one of the configurations. If one
now wishes to plan a dive using this configuration, just highlight the
template dive in the *Dive List* and activate the planner: the planner takes
into account the configuration in the highlighted dive.

=== Printing the dive plan

Selecting the _Print_ button in the planner allows printing of the _Dive
Plan Details_ for wet notes. Alternatively one can cut and paste the _Dive
Plan Details_ for inclusion in a text file or word processing document.

Dive plans have many characteristics in common with dive logs (dive profile,
dive notes, etc).  After a dive plan has been saved, the dive details and
gas calculations are saved in the *Dive Notes* tab. While a dive plan is
being designed, it can be printed using the _Print_ button in the dive
planner. This prints the dive details and gas calculations in the _Dive Plan
Details_ panel of the dive planner. However, after the plan has been saved,
it is represented in a way very similar to a dive log and the gas
calculations cannot be accessed in the same way as during the planning
process. The only way to print the dive plan is to use the _File->Print_
facility on the main menu in the same way as for dive logs or by copy and
paste to a word processor.

[[S_Configure]]
== Configuring a dive computer

_Subsurface_ enables one to configure a dive computer. Currently the
Heinrichs-Weikamp (OSTC 2, OSTC 3) and Suunto Vyper (Stinger, Mosquito, D3,
Vyper, Vytec, Cobra, Gekko and Zoop) family of dive computers are
supported. A large number of settings of these dive computers can be read
and changed to different values. As a first step, ensure that the
appropriate hardware driver is installed for the dive computer and that the
device name of the dive computer is known.  See
<<_appendix_a_operating_system_specific_information_for_importing_dive_information_from_a_dive_computer,APPENDIX
A>> for information on how to do this.

Once the dive computer is connected to the _Subsurface_ computer, select
_File->Configure dive computer_ from the _Main Menu_. Provide the
appropriate device name in the text box at the top of the configuration
panel that opens and select the appropriate dive computer model from the
panel on the lefthand (see image below).

image::images/Configure_dc_f20.jpg["FIGURE: Configure dive computer", align="center"]

Using the appropriate buttons on the configuration panel, the following
actions can be performed:

 - *Retrieve available details*. This loads the existing configuration from the dive computer
   to _Subsurface_, showing this in the configuration panel.
 - *Save changes to device*. This changes the configuration of the
   dive computer to correspond to the information shown in the configuration panel.
 - *Backup*. This saves the configuration data to a file. _Subsurface_ asks for
   a file location and file name for the saved information.
 - *Restore backup*. This loads the information from a backup file and displays it
   in the configuration panel.
 - *Update firmware*. If new firmware is available for the dive computer, this is
   loaded into the dive computer.

== Description of the Subsurface Main Menu items

This section describes the functions and operation of the items in the Main
Menu of Subsurface. Several of the items below are links to sections of this
manual dealing with the appropriate operations.

=== File
<<S_NewLogbook,_New Logbook_>> - Close the currently open dive logbook and
clear all dive information.
_Open logbook_ - This opens the file manager in order to select a dive
logbook to open.
- _Save_ - Save the dive logbook that is currently open.
- _Save as_ - Save the current logbook under a different file name.
- _Close_ - Close the dive logbook that is currently open.
<<S_ExportLog,_Export_>> - Export the currently open dive logbook (or the
selected dives in the logbook) to one of several formats.
- <<S_PrintDivelog,_Print_>> - Print the currently open logbook.
- <<S_Preferences,_Preferences_>> - Set the _Subsurface_ preferences.
- <<S_Configure,_Configure dive computer_>> - Edit the configuration of a dive
  computer.
- _Quit_ - Quit _Subsurface_.

=== Import
<<S_ImportDiveComputer,_Import from dive computer_>> - Import dive
information from a dive computer.
<<Unified_import,_Import Log Files_>> - Import dive information from a file
in in a _Subsurface_-compatible format.
<<S_Companion,_Import GPS data from Subsurface web service_>> - Load GPS
coordinates from the _Subsurface_ mobile phone app.
<<S_ImportingDivelogsDe,_Import from Divelogs.de_>> - Import dive
information from _www.Divelogs.de_.

=== Log
- <<S_EnterData,_Add Dive_>> - Manually add a new dive to the *Dive List*
  panel.
- <<S_DivePlanner,_Plan Dive_>> - This feature allows the planning of dives.
- <<S_Replan,_Re-plan dive_>> - Edit a dive plan that has been saved into the
  *Dive List*.
- <<S_CopyComponents,_Copy dive components_>> - By selecting this option, one
  can copy information from several fields of a dive log onto the clipboard.
- _Paste dive components_ - Paste, into the selected dives in the *Dive List*,
   the information copied using the _Copy dive components_ option.
<<S_Renumber,_Renumber_>> - Renumber the dives listed in the *Dive List*
panel.
<<S_Group,_Auto Group_>> - Group the dives in the *Dive List* panel into
dive trips.
- <<S_DeviceNames,_Edit Device Names_>> - Edit the names of dive computers to
  facilitate your logs.
- <<S_Filter,_Filter divelist_>> - Select only some dives, based on specific
  tags or dive criteria.

=== View
<<S_ViewPanels,_All_>> - View the four main _Subsurface_ panels
simmultaneously.
- <<S_ViewPanels,_Dive List_>> - View only the *Dive List* panel.
- <<S_ViewPanels,_Profile_>> - View only the *Dive Profile* panel.
- <<S_ViewPanels,_Info_>> - View only the *Dive Notes* panel.
- <<S_ViewPanels,_Globe_>> - View only the *World Map* panel.
_Yearly Statistics_ - Display summary statistics about dives during this and
past years.
- _Prev DC_ - Switch to previous dive computer.
- _Next DC_ - Switch to next dive computer.
- _Full Screen_ - Toggles Full Screen mode.

=== Help
_About Subsurface_ - Show a panel with the version number of _Subsurface_ as
well as licensing information.
_Check for updates_ - Find out whether a newer version of Subsurface is
available on the http://subsurface-divelog.org/[_Subsurface_ web site].
- _User Manual_ - Open a window showing this user manual.


== APPENDIX A: Operating system specific information for importing dive information from a dive computer.

=== Make sure that the OS has the required drivers installed
[icon="images/icons/drivers.jpg"]
[NOTE]
The operating system of the desktop computer needs the appropriate drivers
in order to communicate with the dive computer in whichever way the dive
computer prefers (e.g. bluetooth, USB, infra-red).

	* On Linux users need to have the correct kernel module loaded. Most
	  distributions will do this automatically, so the user does not need to load
	  kernel modules. However, some communication protocols require an additional
	  driver, especially for rarely used technology such as infra-red.

	* On Windows, the OS should offer to download the correct driver once the user
	  connects the dive computer to the USB port and operating system sees the
	  equipment for the first time.

On a Mac users sometimes have to manually hunt for the correct driver. For
example the correct driver for the Mares Puck devices or any other dive
computer using a USB-to-serial interface based on the Silicon Labs CP2101 or
similar chip can be found as _Mac_OSX_VCP_Driver.zip_ at the
http://www.silabs.com/support/pages/document-library.aspx?p=Interface&f=USB%20Bridges&pn=CP2101[Silicon
Labs document and software repository].

[[S_HowFindDeviceName]]
=== How to Find the Device Name for USB devices and set its write permission
[icon="images/icons/usb.jpg"]
[NOTE]
When a user connects the dive computer by using a USB connector, usually
_Subsurface_ will either propose a drop down list that contains the correct
device name (or mount point for the Uemis Zurich), or it will disable the
device select drop down if no device name is needed at all. In the rare
cases where this doesn't work, here are some suggestions of ways to find out
what the device name is:

.On Windows:

Simply try COM1, COM2, etc. The drop down list should contain all connected
COM devices.

.On MacOS:

The drop down box should find all connected dive computers.

.On Linux:

There is a definitive way to find the port:

 - Disconnect the USB cable from the dive computer
 - Open a terminal
 - Type the command: 'dmesg' and press enter
 - Plug in the USB cable of the dive computer
 - Type the command: 'dmesg' and press enter

A message similar to this one should appear:

	usb 2-1.1: new full speed USB device number 14 using ehci_hcd
	usbcore: registered new interface driver usbserial
	USB Serial support registered for generic
	usbcore: registered new interface driver usbserial_generic
	usbserial: USB Serial Driver core
	USB Serial support registered for FTDI USB Serial Device
	ftdi_sio 2-1.1:1.0: FTDI USB Serial Device converter detected
	usb 2-1.1: Detected FT232BM
	usb 2-1.1: Number of endpoints 2
	usb 2-1.1: Endpoint 1 MaxPacketSize 64
	usb 2-1.1: Endpoint 2 MaxPacketSize 64
	usb 2-1.1: Setting MaxPacketSize 64
	usb 2-1.1: FTDI USB Serial Device converter now attached to ttyUSB3
	usbcore: registered new interface driver ftdi_sio
	ftdi_sio: v1.6.0:USB FTDI Serial Converters Driver

The third line from the bottom shows that the FTDI USB adapter is detected
and connected to +ttyUSB3+. This information can now be used in the import
settings as +/dev/ttyUSB3+ which directs Subsurface to the correct USB port.

Ensuring that the user has write permission to the USB serial port:

On Unix-like operating systems the USB ports can only be accessed by users
who are members of the +dialout+ group. If one is not root, one may not be a
member of that group and will not be able to use the USB port. Let us assume
one's username is 'johnB'.

As root, type: +usermod -a -G dialout johnB+ (Ubuntu users: +sudo usermod -a
-G dialout johnB+)  This makes johnB a member of the +dialout+ group.
Type: +id johnB+     This lists all the groups that johnB belongs to and
verifies that
the appropriate group membership has been created. The +dialout+ group should
be listed
among the different IDs.
Under some circumstances this change takes only effect (eg. on Ubuntu) after
one logs out and then logs in again.

With the appropriate device name (e.g. +dev/ttyUSB3+) and with write
permission to the USB port, the dive computer interface can connect and one
should be able to import dives.

[[S_HowFindBluetoothDeviceName]]
=== Setting up bluetooth enabled devices
[icon="images/icons/bluetooth.jpg"]
[NOTE]
For dive computers communicating through bluetooth like the Heinrichs
Weikamp Frog or the Shearwater Predator and Petrel there is a different
procedure to get the devices name to communicate with _Subsurface_. Follow
these steps:

 * *For the dive computer, after enabling Bluetooth, ensure it is in Upload mode.*

For Bluetooth pairing of the dive computer, refer to the manufacturer's user
guide. When using a Shearwater Predator/Petrel, select _Dive Log -> Upload
Log_ and wait for the _Wait PC_ message.

 * *Pair the _Subsurface_ computer with the dive computer.*

.On Windows:

Bluetooth is most likely already enabled. For pairing with the dive computer
choose _Control Panel->Bluetooth Devices->Add Wireless Device_.  This should
bring up a dialog showing your dive computer (in Bluetooth mode) and
allowing pairing. Right click on it and choose _Properties->COM Ports_ to
identify the port used for your dive computer. If there are several ports
listed, use the one saying "Outgoing" instead of "Incoming".

For downloading to _Subsurface_, the _Subsurface_ drop-down list should
contain this COM port already. If not, enter it manually.

Note: If there are issues afterwards when downloading from the dive computer
using other software, remove the existing pairing with the dive computer.

.On MacOS:

Click on the Bluetooth symbol in the menu bar and select _Set up Bluetooth
Device..._. The dive computer should then show up in the list of
devices. Select it and go through the pairing process. This step should only
be needed once for initial setup.

Once the pairing is completed the correct device is shown in the 'Device or
Mount Point' drop-down in the _Subsurface_ *Import* dialog.

.On Linux
Ensure Bluetooth is enabled on the _Subsurface_ computer.  On most common
distributions this should be true out of the box and pairing should be
straight forward. For instance, Gnome3 shows a Bluetooth icon in the upper
right corner of the desktop where one selects 'Set up New Device'. This
should show a dialog where one can select the dive computer (which already
should be in Bluetooth mode) and pair it.  If a PIN is required, try
manually setting '0000'.

In the rare cases where the above is not true, then depending on your
system, try +initd+ or +systemd+. This might be different and also involve
loading modules specific to your hardware. In case your system is running
+systemd+, manually run +systemctl start bluetooth.service+ to enable it, in
case of +initd+, run something like +rc.config start bluetoothd+ or
+/etc/init.d/bluetooth start+.

One may also use a manual approach by using such commands:

+hciconfig+ shows the Bluetooth devices available on your computer (not dive
computer), most likely one will see a hci0, if not try +hcitool -a+ to see
inactive devices and run +sudo hciconfig hci0 up+ to bring them up.

+hcitool scanning+ gets a list of bluetooth enabled client devices, look for
the dive computer and remember the MAC address are shown there

+bluez-simple-agent hci0 10:00:E8:C4:BE:C4+ pairs the dive computer with the
bluetooth stack of the _Subsurface_ computer, copy/paste the MAC address
from the output of 'hcitool scanning'

Unfortunately on Linux binding to a communication device has to be done
manually by running:

+rfcomm bind /dev/rfcomm0 10:00:E8:C4:BE:C4+ binds the dive computer to a
communication device in the desktop computer, in case rfcomm is already
taken use rfcomm1 or up. IMPORTANT: Copy/paste the MAC address from the
output of +hcitool scanning+, the MAC address shown above will not work.

For downloading dives in _Subsurface_ specify the device name connected to
the MAC address in the last step above, e.g. _/dev/rfcomm0_.


== APPENDIX B: Dive Computer specific information for importing dive information.

[[S_ImportUemis]]
=== Import from a Uemis Zurich

[icon="images/icons/iumis.jpg"]
[NOTE]
_Subsurface_ downloads the information stored on the SDA (the built-in file
system of the Uemis) including information about dive spots and
equipment. Buddy information is not yet downloadable.  Things are very
similar to a normal USB-connected dive computer (the Uemis is one of those
that recharge when connected to the USB port).  The main difference is that
one does not enter a device name, but instead the location where the
UEMISSDA file system is mounted once connected to the dive computer. On
Windows this is a drive letter ( often 'E:' or 'F:'), on a Mac this is
'/Volumes/UEMISSDA' and on Linux systems this differs depending on the
distribution. On Fedora it usually is
'/var/run/media/<your_username>/UEMISSDA'. In all cases _Subsurface_ should
suggest the correct location in the drop down list.

After selecting the above device name, download the dives from the Uemis
Zurich. One technical issue with the Uemis Zurich download implementation
(this is a Uemis firmware limitation, not a _Subsurface_ issue) is that one
cannot download more than about 40-50 dives without running out of memory on
the SDA. This will usually only happen the very first time one downloads
dives from the Uemis Zurich.  Normally when downloading at the end of a day
or even after a dive trip, the capacity is sufficient. If _Subsurface_
displays an error that the dive computer ran out of space the solution is
straight forward.  Disconnect the SDA, turn it off and on again, and
reconnect it. You can now retry (or start a new download session) and the
download will continue where it stopped previously. One may have to do this
more than once, depending on how many dives are stored on the dive computer.

[[S_ImportingGalileo]]
=== Importing dives from the Uwatec Galileo

[icon="images/icons/Galileo.jpg"]
[NOTE]
The Uwatec Galileo dive computers use infra red (IrDA) communication between
the dive computer and Subsurface. The Uwatec hardware uses a USB dongle
based on the serial infra-red (SIR) protocol and the MSC7780 IrDA controller
manufactured by MosChip and marketed by Scubapro and some electronics
companies.  Under Linux, the kernel already provides for communication using
the IrDA protocol. However, the user additionally needs to load a driver for
the IrDA interface with the dive computer. The easiest way is to load the
*irda-tools* package from the
http://irda.sourceforge.net/docs/startirda.html[Linux IrDA Project].  After
the installation of the irda-tools, the *root user* can specify a device
name from the console as follows: +irattach irda0+

After executing this command, Subsurface will recognise the Galileo dive
computer and download dive information.

Under Windows, a similar situation exists. Drivers for the MCS7780 are
available from some Internet web sites e.g.
http://www.drivers-download.com/Drv/MosChip/MCS7780/[www.drivers-download.com].

For the Apple Mac, IrDA communication via the MCS7780 link is not available
for OSX 10.6 or higher.

[[S_ImportingDR5]]
=== Importing dives from Heinrichs Weikamp DR5

[icon="images/icons/HW_DR5.jpg"]
[NOTE]
When mounted as a USB drive the Heinrichs Weikamp DR5 saves a single UDDF
file for every dive.  Mark all the dives you'd like to import or open.
Note: The DR5 does not seem to store gradient factors nor deco information,
so for _Subsurface_ it is not possible to display them. Adjust the gradient
factors in the _Graph Settings_ in _Subsurface_ to generate a deco overlay
in the _Subsurface_ *Dive Profile* panel but please note that the deco
calculated by _Subsurface_ will most likely differ from the one displayed on
the DR5.

=== Import from Shearwater Predator using Bluetooth

[icon="images/icons/predator.jpg"]
[NOTE]
Using a Shearwater Predator one may be able to pair Bluetooth but then
encounter issues when downloading, showing errors like _Slip RX: unexp. SLIP
END_ on the Predator.  This might also arise when using other dive log
software and operating systems other than Linux. We have no detailed idea
about the source and how to fix this, but it is reported to be solved
sometimes by one of these steps:

 * use the Bluetooth dongle which came with the Shearwater Predator instead of
   the built-in one of the _Subsurface_ computer
 * switch to different Bluetooth drivers for the same hardware
 * switch off WiFi while using Bluetooth

[[S_PoseidonMkVI]]
=== Importing dive logs from the Poseidon MkVI Discovery

[icon="images/MkVI.jpeg"]
[NOTE]
Download of dive logs from the MkVI is performed using a custom
communications adapter and the _Poseidon PC Configuration Software_,
obtained when purchasing the MKVI equipment. The latter is a Windows
application allowing configuration of equipment and storage of dive
logs. Communication between dive computer and desktop computer utilises the
IrDA infra-red protocol. Only data for one dive can be downloaded at a time,
comprising three files:

Setup configuration for the dive and key dive parameters (file with a .txt
extension)
- Dive log details (file with a .csv extension)
Redbook format dive log (file with .cvsr extension). This is a compressed
version of the dive log using a proprietary format.

_Subsurface_ accesses the .txt and the .csv files to obtain dive log
information.


=== Importing dive logs from the APD Inspiration CCR

[icon="images/APDComputer.jpg"]
[NOTE]
The dive logs of an APD Inspiration or similar CCR dive computer are
downloaded using a communications adapter and _AP Communicator_, obtained
when purchasing the equipment. The dive logs can be viewed using the _AP Log
Viewer_, within Windows or Mac/OS. However, APD logs can be viewed and
managed from within _Subsurface_ (together with dives using many other types
of dive computer). The APD inspiration dive logs are imported into
_Subsurface_ as follows:

- Open a dive within the _AP Log Viewer_.
- Select the tab at the top of the screen, entitled "_Data_".
- If the raw dive log data show on the screen, click on "_Copy to Clipboard_".
- Open a text editor, e.g. Notepad (Windows), TextWrangler (Mac).
Copy the contents of the clipboard into the text editor and save the text
file with a filename extension of .CSV
- Within _Subsurface_, select _Import->Import log files_ to open the
  xref:Unified_import[universal import dialogue].
- In the dropdown list towards the bottom right of the dialogue, select "_CSV
  files_".
On the list of file names select the .CSV file that has been created
above. An import dialogue opens.
In the dropdown list on the middle right labeled '_Pre-configured imports_",
select _APD Log Viewer_.
- Ensure the other settings for the ADP dive log are appropriate, then select
  _OK_.

The APD dive log will appear within _Subsurface_.


== APPENDIX C: Exporting Dive log information from external dive log software.

The import of dive log data from external dive log software is mostly
performed using the dialogue found by selecting _Import_ from the Main Menu,
then clicking on _Import Log Files_. This is a single-step process, more
information about which can be found xref:Unified_import[here.] However, in
some cases, a two-step process may be required:

Export the foreign dive log data to format that is accessible from
_Subsurface_.
2. Import the accessible dive log data into _Subsurface_.

This appendix provides some information about approaches to export dive log
data from foreign dive log software. The procedures below mostly apply to
Linux and/or Windows.

[[S_ImportingDivesSuunto]]
=== Exporting dives from *Suunto Divemanager (DM3, DM4 or DM5)*
[icon="images/icons/suuntologo.jpg"]
[NOTE]
DiveManager is a MS Windows application for Suunto dive computers.
Divemanager 3 (DM3) is an older version of the Suunto software. More recent
Suunto dive computers use Divemanager version 4 or 5 (DM4 or DM5). The
different versions of Divemanager use different methods and different file
naming conventions to export dive log data.

*Divemanager 3 (DM3):*

1. Start 'Suunto Divemanager 3' and log in with the name containing the logs
2. Do not start the import wizard to import dives from the dive computer.
In the navigation tree on the left side of the program-window, select the
appropriate dives.
4. Within the list of dives, select the dives you would like to import later:
	* To select certain dives: hold 'ctrl' and click the dive
To select all dives: Select the first dive, hold down shift and select the
last dive
5. With the dives marked, use the program menu _File -> Export_
6. The export pop-up will show. Within this pop-up, there is one field called
   'Export Path'.
	* Click the browse button next to the field Export Path
** A file-manager like window pops up
** Navigate to the directory for storing the
Divelog.SDE file
		** Optionally change the name of the file for saving
		** Click 'Save'
	* Back in the Export pop-up, press the button 'Export'
7. The dives are now exported to the file Divelog.SDE.

*Divemanager 4 (DM4) and Divemanager 5 (DM5):*

DM4 and DM5 use identical mechanisms for exporting dive logs.  To export a
divelog from Divemanager one needs to locate the DM4/DM5 database where the
dives are stored. the user can either look for the original database or make
a backup of the dives. Both methods are described here.

Locating the Suunto DM4 (or DM5) database:

1. Start Suunto DM4/DM5
2. Select 'Help -> About'
3. Click 'Copy' after text 'Copy log folder path to clipboard'
4. Now open Windows Explorer
5. Paste the address to the path box at the top of the File Explorer
6. The database is called DM4.db or DM5.db

Making a backup copy of the Suunto DM4/DM5 database:

1. Start Suunto DM4/DM5
2. Select 'File - Create backup'
3. From the file menu select the location and name for the backup, we'll use
   DM4 (or DM5) in here with the default extension .bak
4. Click 'Save'
5. The dives are now exported to the file DM4.bak (or DM5.bak)


=== Exporting from Mares Dive Organiser V2.1
[[Mares_Export]]

[icon="images/icons/mareslogo.jpg"]
[NOTE]
Mares Dive Organiser is a Windows application. The dive log is kept as a
Microsoft SQL Compact Edition database with a '.sdf' filename extension. The
database includes all Dive Organiser-registered divers on the particular
computer and all Mares dive computers used. The safest way to obtain a copy
of the dive database is to export the information to another compatible
format which can be imported into _Subsurface_.

Within Dive Organiser, select _Database -> Backup_ from the main menu and
back up the database to the desk top.  This creates a zipped file
DiveOrganiserxxxxx.dbf.
Rename the file to DiveOrganiserxxxxx.zip. Inside the zipped directory is a
file _DiveOrganiser.sdf_.
3. Extract the _.sdf_ file from the zipped folder to your Desktop.
4. The password for accessing the .zip file is _mares_.

[[S_ImportingDivingLog]]
=== Exporting dives from *DivingLog 5.0*

[icon="images/icons/divingloglogo.jpg"]
[NOTE]
Unfortunately DivingLog XML files give us no indication on the preferences
set on one's system. So in order for _Subsurface_ to be able to successfully
import XML files from DivingLog one first needs to ensure that DivingLog is
configured to use the Metric system (one can easily change this within
Diving Log by selecting 'File -> Preferences -> Units and Language' by
clicking the 'Metric' button). Then do the following:

1. In DivingLog open the 'File -> Export -> XML' menu
2. Select the dives to export
3. Click on the export button and select the filename

[[S_Appendix_D]]
== APPENDIX D: Exporting a spreadsheet to CSV format

Many divers keep a diving log in some form of a digital file, commonly a
spreadsheet with various fields of information. These logs can be easily
imported into _Subsurface_ (xref:S_ImportingManualCSV[Importing dives
from_manually kept CSV file]), after the spreadsheet is converted in a .CSV
file.  This section explains the procedure to convert a diving logbook
stored in a spreadsheet to a .CSV file that will later be imported from
_Subsurface_.  Creating a .CSV is a straightforward task, although the
procedure is somewhat different according to which spreadsheet program is
used.

The first step is to organize the diving data in the spreadsheet, so that
the first row contains the names (or titles) of each column and the
information for each dive is stored in a single row.  _Subsurface_ supports
many data items (Dive #, Date, Time, Duration, Location, GPS, Max Depth,
Mean Depth, Buddy, Notes, Weight and Tags).  The user can organize dive data
following a few simple rules:

1. Date: use one of the following formats: yyyy-mm-dd, dd.mm.yyyy, mm/dd/yyyy
2. Duration: the format should be minutes:seconds.
3. Unit system: only one unit system shold be used (i.e., no mixture between
   imperial and metric units)
4. Tags and buddies: values should be separated using a comma.
5. GPS position: users must use decimal degrees, e.g. 30.22496 30.821798

=== _LibreOffice Calc_ and _OpenOffice Calc_

These are open source spreadsheet applications forming parts of larger open
source office suite applications. The user interaction with _LibreOffice_
and _OpenOffice_ is very similar.  In Libreoffice Calc the time format
should be set to minutes:seconds - [mm]:ss and dates should be set to one
of: yyyy-mm-dd, dd.mm.yyyy, mm/dd/yyyy. A typical dive log may look like
this:

image::images/LOffice_spreadsheetdata.jpg["FIGURE: Spreadsheet data", align="center"]

To export the data as a .CSV file from within LibreOffice click _File ->
Save As_. On the dialogue that comes up, select the _Text CSV (.csv)_ as the
file type and select the option _Edit filter settings_.

image::images/LOffice_save_as_options.jpg["FIGURE: Save as options", align="center"]

After selecting _Save_, select the appropriate field delimiter (choose _Tab_
to prevent conflicts with the comma when using this as a decimal point),
then select _OK_.

image::images/LOffice_field_options.jpg["FIGURE: Field options", align="center"]

One can double check the .CSV file by opening it with a text editor, and
then import the dive data as explained on the section
xref:S_ImportingManualCSV[Importing dives from manually kept CSV files].

=== Microsoft _Excel_

The field delimiter (called "_list separator_" in Microsoft manuals) is not
accessible from within _Excel_ and needs to be set through the _Microsoft
Control Panel_. After changing the separator character, all software on the
Windows machine use the new character as a separator.  One can change the
character back to the default character by following the same procedure,
outlined below.

- In Microsoft Windows, click the *Start* button, and then select _Control
  Panel_ from the list on the right-hand side.
- Open the _Regional and Language Options_ dialog box.
Do one of the following: ** In Windows 7, click the _Formats_ tab, and then
click _Customize this format_.  ** In Windows XP, click the _Regional
Options_ tab, and then click _Customize_.
- Type a new separator in the _List separator_ box. To use a TAB-delimited
  file, type the word TAB in the box.
- Click _OK_ twice.

Below is an image of the _Control Panel_:

image::images/Win_SaveCSV2.jpg["FIGURE: Win List separator", align="center"]

To export the dive log in CSV format:

With the dive log opened in _Excel_, select the round Windows button at the
top left, then _Save As_.

image::images/Win_SaveCSV1.jpg["FIGURE: Excel save as option", align="center"]

Click on the left-hand part of the _Save as_ option, NOT on the arrow on the
right-hand. This brings up a dialogue for saving the spreadsheet in an
alternative format. From the dropdown list at the bottom of the dialogue,
marked _Save as Type:_, select _CSV(Comma delimited) (*.CSV)_. Ensure that
the appropriate folder has been selected to save the CSV file into.

image::images/Win_SaveCSV3.jpg["FIGURE: Excel save CSV dialogue", align="center"]

Select the _Save_ button. The CSV-formatted file is saved into the folder
that was selected. One can double check the .CSV file by opening it with a
text editor, and then import the dive data as explained on the section
xref:S_ImportingManualCSV[Importing dives from manually kept CSV files].

== APPENDIX E: FAQs.

=== Subsurface appears to miscalculate gas consumption and SAC
[[SAC_CALCULATION]]
'Question': I dived with a 12.2 l tank, starting with 220 bar and ending
with 100 bar, and I calculate a different SAC compared what _Subsurface_
calculates. Is _Subsurface_ miscalculating?

'Answer': Not really. What happens is that _Subsurface_ actually calculates
gas consumption differently - and better - than you expect.  In particular,
it takes the incompressibility of the gas into account.  Traditionally, Gas
consumption and SAC should be: +consumption = tank size x (start pressure -
end pressure)+

and that's true for an ideal gas, and it's what you get taught in dive
theory.  But an "ideal gas" doesn't actually exist, and real gases actually
don't compress linearly with pressure. Also, you are missing the fact that
one atmosphere of pressure isn't actually one bar.  So the *real*
calculation is:

+consumption = (amount_of_air_at_beginning - amount_of_air_at_end)+

where the amount of air is *not* just "tank size times pressure in bar".
It's a combination of: "take compressibility into account" (which is a
fairly small issue under 220 bar - you'll see more differences when you do
high-pressure tanks with 300bar) and "convert bar to atm" (which is the
majority of your discrepancy).  Remember: one ATM is ~1.013 bar, so without
the compressibility, your gas use is:

+12.2*((220-100)/1.013)+

which is about 1445, not 1464. So there was 19 l too much in your simple
calculation that ignored the difference between 1 bar and one ATM.  The
compressibility does show up above 200 bar, and takes that 1445 down about
eight litres more, so you really did use only about 1437 l of air at surface
pressure.

So be happy: your SAC really is better than your calculations indicated.  Or
be sad: your cylinder contains less air than you thought it did.  And as
mentioned, the "contains less air than you thought it did" really starts
becoming much more noticeable at high pressure. A 400 bar really does not
contain twice as much air as a 200 bar one. At lower pressures, air acts
pretty much like an ideal gas.

=== Some dive profiles have time discrepancies with the recorded samples from my dive computer...

_Subsurface_ ends up ignoring surface time for many things (average depth,
divetime, SAC, etc).  'Question': Why do dive durations in my dive computer
differ from that given by _Subsurface_?

'Answer': For example, if you end up doing a weight check (deep enough to
trigger the "dive started")  but then come back up and wait five minutes for
your buddies, your dive computer may say that your dive is 50 minutes long -
because you have fifty minutes worth of samples - but subsurface will say
it's 45 minutes - because you were actually diving for 45 minutes.  It's
even more noticeable if you do things like divemastering the initial OW
dives, when you may stay in the water for a long time, but spend most of it
at the surface. And then you don't want that to count as some kind of long
dive”.
