heinrichs weikamp OSTC cR User manual

1
User manual
OSTC dive computer
with the Firmware
hwOS tech
OSTC 2
OSTC 2 TR
OSTC plus
OSTC cR

Thank you for choosing a heinrichs
weikamp dive computer!
The rmware hwOS tech which is used in
the dive computers OSTC plus, OSTC 2, OSTC
2 TR and OSTC cR offers various possibilities
for conguration. For technical diving a full
trimix program with ve gases is available.
Rebreather divers can use xed setpoints,
auto setpoints or sensors for the calcula-
tion.
Data like logbook information or updates
can be transferred easily with Bluetooth.
Take also notice of the large supply of log-
book programs and other software.
The development of the heinrichs weikamp
dive computers is permanently going on.
Use the rmware updates to keep your
OSTC always up to date. Get it for free at:
www.heinrichsweikamp.com
You can use the OSTC intuitively. But to be-
come familiar with its functions and to use
it in the best way, we recommend you to
read this manual carefully. Additionally you
nd some videos on our website and face-
book page which offer some easy explana-
tions (for example how to change the bat-
tery, calibrate the compass or change the
bungees).
Please notice the additional user manuals
for sensor readings with the OSTC cR and
for gas integration in the OSTC 2 TR with
transmitter. This manual also applies to
older models such as the OSTC 3.
We hope you enjoy diving with your new
OSTC dive computer!
Your OSTC
For any questions relating to your OSTC, please contact us:
• Internet forum: www.forum.heinrichsweikamp.com
• E-mail: [e-mail]
• Post: heinrichs weikamp
Adlerstraße 7
79098 Freiburg im Breisgau
Germany
Contact

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Content
1. Common advices……………………………………………………………………………………………………..6
1.1. Technical status………………………………………………………………………………….6
1.2. About this manual…………………………………………………………………………….6
1.3. Functions overview……………………………………………………………………………6
2. Safety advices………………………………………………………………………………………………………….7
2.1. Requirements…………………………………………………………………………………….7
2.2. Before every dive……………………………………………………………………………….7
2.3. While diving……………………………………………………………………………………….8
2.4. Safe use of the OSTC…………………………………………………………………………8
2.5. Environmental conditions……………………………………………………………….8
3. Before rst use…………………………………………………………………………………………………………9
3.1.Handling………………………………………………………………………………………………9
3.2. Modes of operation…………………………………………………………………………10
3.3. Modes of diving………………………………………………………………………………..11
3.4. Compass calibration………………………………………………………………………..12
3.5. Menu functions………………………………………………………………………………..12
4. Surface mode…………………………………………………………………………………………………………13
4.1. Display in surface mode…………………………………………………………………13
4.2. Settings……………………………………………………………………………………………..14
4.2.1.Information…………………………………………………………………14
4.2.2. Bluetooth mode…………………………………………………………14
4.2.3. Set time and date………………………………………………………14
4.2.4.Language……………………………………………………………………..14
4.2.5. Display settings………………………………………………………….15
4.2.6.Logbook offset…………………………………………………………….15
4.2.7.Salinity………………………………………………………………………….15
4.2.8. Adjust buttons……………………………………………………………16
4.2.9. Waiting time………………………………………………………………16
4.2.10. Reset menu………………………………………………………………16
4.3. Deko setup………………………………………………………………………………………..17
4.3.1. Dive mode…………………………………………………………………..17
4.3.2. Deco type…………………………………………………………………….17
4.3.3. Deco parameter………………………………………………………….18
4.3.3.1. Gradient factors…………………………………..18
4.3.3.2. Saturation factors………………………………..18
4.3.3.3. Last deco……………………………………………….19
4.3.4. ppO2 settings……………………………………………………………..19
4.3.5. Safety stop………………………………………………………………….20
4.3.6. Second deco plan……………………………………………………….20
4.3.6.1. Future TTS/Future Bailout…………………..20
4.3.6.2. Calculation gas (B/O)…………………………..20

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4.4. OC gas setup……………………………………………………………………………………..22
4.4.1. Edit gas………………………………………………………………………..22
4.4.1.1. Gas type…………………………………………………22
4.4.1.2. Gas mix………………………………………………….23
4.4.1.3.Changedepth………………………………………..23
4.5. CCR/pSCR setup……………………………………………………………………………….24
4.5.1. Mode……………………………………………………………………………24
4.5.2. Diluent setup………………………………………………………………25
4.5.3.CCRSetpoints………………………………………………………………25
4.5.4. pSCR setup………………………………………………………………….26
4.5.5. Maximum O2 content in the loop…………………………..26
4.6.Simulator…………………………………………………………………………………………..26
4.6.1. Calculate a deco plan………………………………………………..26
4.6.2.Start simulator……………………………………………………………27
4.7.Logbook……………………………………………………………………………………………..28
5. Dive mode………………………………………………………………………………………………………………29
5.1. Display in dive mode………………………………………………………………………29
5.2. Menu in dive mode…………………………………………………………………………30
5.2.1. Gas change (OC)…………………………………………………………30
5.2.2.Stoppwatch…………………………………………………………………31
5.2.3. Toggle GF…………………………………………………………………….32
5.2.4. Set marker…………………………………………………………………..32
5.2.5.Bearing…………………………………………………………………………32
5.2.6.Layout…………………………………………………………………………..33
5.2.7. Setpoint change…………………………………………………………33
5.2.8.Bailout………………………………………………………………………….33
5.2.9.Diluent………………………………………………………………………….33
5.3. Warnings…………………………………………………………………………………………..34
5.4. Views in dive mode…………………………………………………………………………36
6.Maintenance…………………………………………………………………………………………………………..37
6.1.Housing……………………………………………………………………………………………..37
6.2.Bungee……………………………………………………………………………………………….37
6.3. Recharge the battery……………………………………………………………………….37
6.4. Change the battery………………………………………………………………………….38
6.5. Spare parts………………………………………………………………………………………..38
7. Software and updates…………………………………………………………………………………………..38
7.1. Firmware update……………………………………………………………………………..38
7.2. Software for the OSTC…………………………………………………………………….39
8. Technical Data……………………………………………………………………………………………………….40
9.Disposal……………………………………………………………………………………………………………………41

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1.1. Technical status
This manual corresponds to the technical
status of OSTC and its rmware hwOS tech
as of March 2019.
(Firmware hwOS tech 3.01)
OSTC, its rmware and the documentation
are subject to technical changes without
notice.
The OSTC rmware (integrated software) is
an ongoing development. To make the best
use of OSTC, we advise you to use the latest
stable rmware available on our website:
www.heinrichsweikamp.com
1.2. About this manual
Read this manual carefully, so you can set
up and use the dive computer in the right
way. Keep this manual so you can consult
it also at a later time. You also nd the lat-
est version for download as PDF on our
homepage.
Special markings
!Warning
indicates a situation that carries a signi-
cant risk or injury.
Caution
indicates a situation that carries a risk of
damage to the device.
Note
indicates additional information.
Standard settings
Unless noted otherwise, the information
in this manual refers to OSTC standard set-
tings.
For important settings, the OSTC shows an
asterisk * behind the current setting, if the
current setting is different from the default
setting.
Terms of use
Copying or reusing this manual or parts
of this manual is not allowed without the
written permission of heinrichs weikamp.
1.3. Functions overview
Your dive computer OSTC assists you with
the following functions:
Display: Diving depth and duration accord-
ing to EN 13319, maximum diving depth,
ambient temperature, ambient pres-
sure, bottom time, duration and depth of
planned deco stops, time to desaturation
based on diving depth and duration.
Additional informations: tilt-compensated
compass, average depth, stopwatch, ppO2,
CNS.
Planning: Congure and check gas mix-
tures as well as setpoints in CCR mode, cal-
culate a deco plan in the simulator.
Record: Time, duration, depth prole, tem-
perature, reference pressure and time of de-
saturation.
1. Common advices

7
2.1. Requirements
The most important factor for safe diving is
a competent and well trained diver.
This dive computer is intended for experi-
enced divers. That implies:
A diving education including decompres-
sion diving is mandatory. Sufficient know-
ledge about the laws of physics in diving
is required. It may harm your health if you
rely on a wrong congured dive computer.
Do not use this dive computer, if you do not
know or understand the settings and dis-
played information of the OSTC.
If necessary, you must be able to nish your
dive safely without a dive computer.
Do not adjust decompression parameters if
you are not aware of their meanings.
2.2. Before every dive
Plan your dive.
Set up a dive plan independently from OSTC
and take it with you when diving.
Make sure that your OSTC is ready for use
and correctly congured.
Always conrm the following questions be-
fore diving:
Stable rmware?
Use only stable rmware provided by hein-
richs weikamp. It has been tested and al-
lows a proper and reliable performance of
OSTC.
Congured correctly?
Check the settings of your OSTC. If neces-
sary, adjust the settings according to your
dive plan and equipment.
Battery full?
Check the battery status using the battery
indicator on the display. To ensure reliable
performance throughout your dive, the sta-
tus of the rechargeable battery must be suf-
ciently high. We recommend to recharge it
at 20 percent of performance at the latest.
If you use an AA battery for your OSTC plus
you should also replace it at 20 percent of
performance.
Device waterproof?
The models OSTC 2 and OSTC 2 TR are com-
pletely closed and have no openings that
could cause leakages. But for safety check
the housing for cracks or damages which
might allow water to intrude. For OSTC plus
(battery compartment), OSTC cR (S8 con-
nector) and older models with USB port
check if all openings are closed.
Safely attached?
Make sure that your OSTC can be fastened
safely using either the bungees or a suita-
ble alternative.
Display messages?
Check the screen of the OSTC. Do not dive
if your dive computer shows a warning.
Check the cause of the warning.
2. Safety advices

8
2.3. While diving
Take a backup system with you.
While diving, always carry a backup system
to measure duration and depth of your dive
independently from OSTC.
Take a sufficiently long surface break be-
fore diving again.
The OSTC doesn’t indicate how long to wait
before the next dive. It just shows the du-
ration time of the interval. Please follow
the guidelines you were taught during your
dive training.
Take the OSTC with you on every repeat
dive – do not lend it to anyone.
A correct calculation of tissue saturation re-
quires that your OSTC is:
•conguredcorrectly
•usedoneverydive
•onlyusedduringyourowndive(andnot
shared with others)
!Warning
Saturation data is lost when updating the
OSTC rmware or in the unlikely event of
a failure. In these cases, do not dive any
further until tissue saturation has returned
to normal level.
2.4. Safe use of the OSTC
Do not modify the hardware. Modications
to the hardware of OSTC can damage its
proper function and the watertightness of
its housing.
Only the bungee backplate, the cap of the
battery compartment (OSTC plus and OSTC
sport) and the cap of the S8 connector
(OSTC cR) can be removed. There is no other
way to open the housing without damag-
ing the device.
Keep your OSTC out of children´s reach.
Small parts such as the battery cap (OSTC
plus, OSTC sport) may represent a choking
hazard.
Caution
Surpassing the maximum water depth of
120 meters may cause malfunction or per-
manent damage of the device.
2.5. Environmental conditions
Store the OSTC in a cool, dry place.
Permissible temperature range for use and
storage: between -5 °C and 40 °C.
Maximum water depth for operation:
120 meters.
If you use an AA battery for the OSTC plus:
Make sure that the used battery is suitable
for the ambient temperature to be expect-
ed in your dives. For cold water diving (un-
der 10°C) we recommend the use of a 1,5V
Lithium battery.
Note
Decompression calculations and depth are
always based on the actual surface pres-
sure. So if you are diving in mountain lakes,
no further settings are needed. OSTC auto-
matically adapts to the actual surface pres-
sure.

9
heinrichs weikamp delivers the OSTC ready
to use. But nevertheless check the battery
status before using it the rst time.
The OSTC is attached to the arm with bun-
gee. The bungee is already installed (Bun-
gees, page 37). To tighten the bungee, make
a knot above the circular cavity. Cut remain-
ing bungee and use a lighter to melt the
small remains of nylon.
3.1. Handling
Operate the OSTC with the two piezo but-
tons on the left and right side of the hous-
ing. A short press is enough to trigger the
buttons. You can adjust individually how
sensitive the buttons shall react (look for
page 16).
To turn on the OSTC, press one of the two
buttons. If the OSTC does not wake up at
once, it is in deep sleep mode (look for next
page). To wake it up, press the button once
more after 5 seconds.
From start screen you can scroll the cus-
tom view in the middle with the right but-
ton (View) and enter the menu with the left
button (Menu). Inside the menu you can
scroll the items with the left button (NEXT)
and conrm with the right button (ENTER).
You only have to press one button at a time.
From the last item on the bottom, the cur-
sor jumps back to the top with the next
press.
In some menus you will nd the entry
MORE. Select this entry to access the next
menu page with more menu items. To quit
the menu or submenu, choose EXIT.
To change the setting of a menu item, press
ENTER repeatedly until the required value is
displayed. For important settings that vary
from the default values, the OSTC shows an
asterisk * behind the current setting.
3. Before rst use
MENU/NEXT VIEW/ENTER

10
3.2. Modes of operation
The OSTC has three modes of operation
and switches automatically between them:
Surface mode, dive mode and sleep mode.
Surface mode
In surface mode you can adjust the settings
for the next dive, adjust the base settings of
the OSTC and read recorded dive data.
To turn on the OSTC, press one of the two
buttons. If it does not wake up at once and
is in deep sleep mode (look for sleep mode),
push the button once more after 5 seconds.
In surface mode the display shows gener-
al information as time, date, temperature,
ambient pressure and battery status. After
a dive the display also shows the elapsed
time since last dive, tissue saturation and
the no y time.
Dive mode
The OSTC automatically switches into dive
mode when it is at 1,6 meter below the sur-
face for ve seconds (also when it is in sleep
mode).
Note
We recommend that you manually turn on
your dive computer before the dive to check
the settings.
In dive mode the display shows current div-
ing depth, dive time, maximum depth, the
currently selected gas (in CCR diving the
setpoint and the current diluent gas), de-
compression information and additional
information.
It is not possible to switch underwater from
dive mode to surface mode. You cannot
change the base settings while diving. Note
that exceptions apply to the apnea mode.
Sleep mode
When the OSTC isn’t operated at the sur-
face, it switches into sleep mode after two
minutes to save energy.
In sleep mode the display is turned off. Am-
bient pressure is measured at regular inter-
vals. After diving, decompression calcula-
tion continues.
After 15 minutes in sleep mode, OSTC
switches to deep sleep mode. In deep sleep
no buttons are polled, which saves a lot of
energy. Move the dive computer and wait 5
seconds until it wakes up. Now you can turn
it on with the buttons.
Also in deep sleep mode the OSTC switch-
es automatically to dive mode after 5 sec-
onds .
The OSTC starts the dive mode automatically when
it is below 1,6 meters depth.

11
3.3. Modes of diving
In the main menu you can choose under
Deco Setup > Dive Mode, if you want to
use the OSTC for scuba diving, rebreather
diving with a CCR or pSCR, apnea diving
or as depth gauge. The chosen dive mode
is shown permanently on the main display
(OC, CC, pSCR, apnea, gauge)
OC (Open Circuit)
Use this dive mode for scuba diving with an
open circuit. This setting is preset on your
OSTC.
CCR (Closed Circuit Rebreather)
Use this dive mode for diving with a CCR re-
breather.
pSCR
Use this dve mode for diving with a pSCR
rebreather.
The decompression calculation model
for OC, CC and pSCR is Bühlmann ZH-L16
without gradient factors or Bühlmann ZH-
L16+GF with gradient factors (read more
on page 17). You can switch from ZH-L16 to
ZH-L16+GF with Decotype. With Deco Pa-
rameters you can adjust the saturation fac-
tors and gradient factors.
Apnea
Use this dive setting for apnea diving or
snorkeling.
In apnea mode the OSTC serves as a depth
gauge. It displays depth, dive time and tem-
perature on the main screen, clock and
compass in the custom view (right but-
ton). Additionally it offers information for
the whole session: Maximum depth, sur-
face time, depth of the last descent and the
total time of underwater time. Decompres-
sion calculation is switched off.
In apnea mode the OSTC remains in dive
mode even when diving at low depths. You
can switch into surface mode at any time
by pushing the left button. Push ENTER to
conrm the QUIT? question.
The OSTC switches automatically from ap-
nea mode into surface mode after a 15 min-
utes delay and above a depth of 1 meter.
Apnea dives are not stored in the logbook.
Gauge
With this dive setting, OSTC serves as a
depth gauge. Decompression and satura-
tion calculation are switched off.
It displays depth, maximum depth, dive
time, temperature, clock, battery status,
compass and average depth. In the menu
you can set the stopwatch and calculate the
average depth from new.
The dive mode of the dive computer is shown per-
manently on the display. In this case OC for Open
Circuit (scuba diving) is active.

12
3.4. Compass calibration
OSTC has a tilt-compensated electronic
compass. Like all other electronic compass-
es it must be calibrated before use. The cal-
ibration compensates aberration that can
be caused by the battery. It is also recom-
mended to calibrate the compass if your
dive computer shows deviations in the
heading reading.
Start the calibration with Settings > More >
Compass Calibration.
For an exact heading, the calibration of the
compass is absolutely necessary.
After starting the calibration menu, move
the dive computer slowly around each axis.
Do this a number of times within 60 sec-
onds. After this while the calibration ends
automatically. During the calibration rou-
tine the OSTC shows X-, Y- and Z-axis.
Note
The order of the axis rotation is not impor-
tant. Keep the dive computer away from
any metallic object during the calibration
process (at least 50 centimeters).
y
z
x
3.5. Menu functions
In the main menu you can adjust the set-
tings to prepare the next dive, adjust the
base settings of the OSTC and review your
dives in the logbook.
Logbook
Recorded data from recent dives.
OC Gas Setup
Set up your gas mix for scubadiving or your
bailout gases for CCR and pSCR diving. You
can congure up to ve gases (air, helium,
oxygen up to 100 percent).
CCR/pSCR Setup
Settings for rebreather diving (CCR and
pSCR). Congure setpoints and diluent gas-
es for CCR diving as well as O2 drop and
lung ratio for pSCR diving.
Simulator
Calculate deco and simulate the dive mode.
Deco Setup
Settings for deco calculation and dive
modes of the OSTC (open circuit, closed cir-
cuit, pSCR, gauge or apnea).
Settings
Settings for time, language, display bright-
ness, compass and more. Start Bluetooth
and reset menu.
Exit
Exit the main menu.
These functions are described in the follow-
ing chapters of this manual.

13
4.1. Display in surface mode
Permanent items
On the start screen the OSTC shows the fol-
lowing items permanently:
•ambientpressure,clock,date
•temperature
•battery:level,typeandvoltage
•divemode:Opencircuit(OC),Closed Cir-
cuit (CCR), pSCR, Gauge or Apnea
•rstgasfordiving
•after diving: time since last dive, no y
time, desaturation and surface interval.
Warnings for missed deco and too high
CNS.
4. Surface mode
Selectable items
In the middle part of the display you can
see extra information in the custom view.
You can switch them with the right button
(View).
•personaltext(upto60characters)
•compass
•gaslist (OC) or setpoints, diluents and
bailout in CC mode, diluents and bailout
in pSCR mode
•currentsettings:decotype,gradientorsa-
turation factors, time of future TTS, last
deco, salinity
•elapsedtimesincelastdive,durationand
maximum depth of the last dive
•desaturationdiagram(Afterthedive,you
can see the approximate tissue saturation
in the desaturation diagram. The 16 types
of tissue according to the Bühlman mo-
del are arranged horizontally. The fastest
tissue is on top, the slowest is below. The
longer the line, the more saturated is the
tissue.)
On the start screen you can scroll the custom view
with the right button and enter the main menu with
the left button.
You can scroll a lot of information in the custom
view, like details of the last dive (top) or the current
deco settings (bottom). First gas and dive mode are
shown permanently.

14
4.2. Settings
In the settings menu you can set up basic
congurations (like clock, language, display
brightness, button sensitivity). You can ac-
tivate Bluetooth and reset all settings and
values.
4.2.1. Information
Shows some device specic information
like serial number, installed rmware ver-
sion, number of total dives, type of battery
and the total runtime.
4.2.2. Bluetooth mode
Activate the Bluetooth Mode in the main
menu with ENTER. On the display appears
»Starting … done« and the Bluetooth is ac-
tive. After activating you have four minutes
to connect the OSTC with your personal
computer or smartphone.
When there is no connection, the Bluetooth
menu terminates automatically. You can
also stop it with the right button ENTER.
When connecting your OSTC to a person-
al computer the rst time, you need to
»pair« your dive computer with the device.
This process depends on the operation sys-
tem of the computer. In Windows: Click the
Bluetooth symbol in the system tray and se-
lect the option »add device«. You don’t need
a PIN code.
When the connecting is done, the PC cre-
ates a virtual COM port. Via this the PC soft-
ware communicates with the OSTC. You do
not need any special drivers, you only have
to select the correct COM port (outgoing
port, SPP).
4.2.3. Set time and date
Menu to set time and date. With Set time
you can set the time, with Set date you
can set the date of the internal clock of the
OSTC. You can change the values for time
and date with the ENTER button.
Choose a date format:
YYMMDD: year, month, day
DDMMYY: day, month, year (default)
MMDDYY: month, day, year
Note
You can also set up time and date with your
personal computer, as well as the personal
text on the start screen.
4.2.4. Language
The OSTC can be set up in English or Ger-
man (standard). To use the languages Ital-
ian and French, download the suitable
rmware from our homepage:
www.heinrichsweikamp.com
With MORE you can enter further sub menus.

15
4.2.5. Display settings
Brightness
The three settings Eco, Medium and High
set different brightness levels for your dis-
play. Within these levels, the OSTC uses an
ambient light sensor to adapt to the cur-
rent light conditions (not OSTC cR). In most
cases the default Eco is recommended. If
the OSTC is often used in low depths and
bright sunlight, a higher setting is recom-
mended.
Default: Eco
Colour scheme
Choose the colour of the display in dive
mode. You can choose the schemes red,
green, blue and standard (white)
Default: Standard
Rotate screen
The display can be also shown upside down.
Default: No
MOD warning
When this menu is activated, the diving
depth turns red when it exceeds the MOD
(maximum operating depth).
Default: No
IBCD warning
Activate a warning of isobaric counter dif-
fusion after gas change (more on page 35).
Default: No
Variable speed
The warning for the rate of ascent is adjust-
ing to the depth. It varies from 7 to 20 me-
ters per minute. If you choose No, the value
10 m/min will be used during the whole dive
as threshold value for an ascent warning.
Default: No
Speed graph
Shows the rate of ascent in a graph, other-
wise only in numbers.
Default: No
Dive timeout
After diving the OSTC shows a countdown
of ve minutes (pre-set). When you de-
scend again within this period, the whole
time of diving will be saved in the logbook
as only one dive. You can adjust the period
individually. Upon a depth of 1 meter, the
dive can also be stopped manually.
Setting range: 1 – 20 minutes
Default: 5 minutes
Units
Display of depth and temperature in metric
(m/°C) or imperial (ft/°F) units.
Default: m/°C
4.2.6. Logbook offset
The dives in the logbook have sequen-
tial numbers. With the logbook offset you
can adjust this numbers to your person-
al number of dives. So the last dive is not
shown as dive number 1 but as number
349, if you have made 349 dives in total yet.
This value will be increased automatical-
ly after every dive (Not for simulated dives).
4.2.7. Salinity
This setting allows you to adjust if you dive
in salt water or in fresh water. This value
has a slight effect on the display of the ac-
tual and maximum depth. To increase this
value, push ENTER repeatedly until the re-
quired value is displayed.
Setting range: 0% – 4%
Default: 0%
Note
Decompression information is based on ab-
solute pressure and not on relative pressu-
re. Therefore salinity does not effect this
calculation.

16
4.2.8. Adjust buttons
You can adjust the sensitivity of the piezo
buttons and how strong you have to press
them. The higher the value, the harder you
have to press. Press ENTER until the re-
quired value is displayed
Setting range: 20% – 80%
Default: 40%
4.2.9. Waiting time
Besides the no y time, that indicates how
long you should not y after diving, the
OSTC can also indicate the time you should
wait to do an ascent up to 1000, 2000 or
3000 meters after diving.
For the no y time, a cabin pressure of 0.6
bar is used; the current ambient pressure
is continuously included in the calculation.
Setting range: Flying, 1000 m, 2000 m,
3000 m
Default: Flying
4.2.10. Reset menu
In the reset menu you can put the settings
of the OSTC to its default values and start
the dive computer from new. You can reset
your decompression information and clear
the logbook.
Reboot
During a rmware update it may be re-
quired to reboot the OSTC. Choose reboot
and push ENTER. You`ll be prompted to con-
rm the action. A reboot also deletes the
current decompression data.
Reboot deco
To delete the current decompression data
choose reset deco and push ENTER. You`ll
be prompted to conrm the action. For the
next dive the OSTC starts decompression
calculation from new, without any data of
former tissue load.
!Warning
Use reboot and reboot deco only, if you do
not plan a repetitive dive within the next 48
hours.
Reset all
Resets all settings (not time and date) to
factory defaults. You’ll be prompted to con-
rm the action. Dives in the logbook and
the dive counter will not be reset.
Desaturation and no y time will remain.
Reset logbook
Deletes all data in the logbook. The coun-
ter starts again with zero. If you want your
personal number of dives to be shown in
the logbook, you have to set up (again) the
number via logbook offset.
Reset battery
When replacing the battery you have to
choose the battery type (OSTC plus). If you
were wrong, you can correct your informa-
tion in this menu (how to change the bat-
tery, page 38).

17
4.3. Deco setup
In deco setup you can congure the dive
mode of your OSTC and select important
settings for the decompression calculation.
4.3.1. Dive mode
You can switch between the dive modes for
open circuit (OC), closed circuit rebreather
(CCR), pSCR, gauge mode or apnea diving.
The current dive mode is shown perma-
nently both in surface mode and dive mode.
Default: OC
4.3.2. Decotype
Toggles between decompression calcula-
tion using the Bühlmann ZH-L16 algorithm
or the Bühlmann ZH-L16+Gf with gradient
factors.
ZH-L16
The classical algorithm Bühlmann ZH-L16
calculates with maximum values (M-val-
ues) wich should not be exceeded. As safety
margin to the M-values (100 percent) this
deco model uses saturation factors. The
OSTC is preset to a value for saturation of
110 percent and a value for desaturation of
90 percent. Thereby there is a safety margin
of 10 percent to the M-value.
Default: Saturation: 110%,
Desaturation: 90%
ZH-L16+GF
The more modern algorithm Bühlmann ZH-
L16+GF with gradient factors calculates
with deeper decostops and a much bigger
safety margin to the M-value. So you have
less micro bubbles in your tissues. The GF
low controls the allowed saturation for the
deepest decostop, the GF high does it with
the highest decostop. The OSTC is preset to
a GF low of 30 percent and a GF high of 85
percent (GF 30/85). With a GF low of 30 per-
cent, you start your decompression with a
safety margin of 70 percent to the M-value.
At the surface your current GF will be 85%
of the M-Value.
The model ZH-L16+GF can be set addition-
ally to a more conservative level with the
saturation factors (page 19).
Default: GF 30/85, Saturation: 100%, Desa-
turation 100%
We suggest using the algorithm ZH-L16+GF
with gradient factors.
The display for a single decostop is limit-
ed to 99 minutes. If a stop is longer than 99
minutes, another stop is generated at the
same depth.
Menu overview »deco setup«.

18
4.3.3. Deco parameter
You can modify the deco model with the
saturation and gradient factors and adjust
it to your own needs.
4.3.3.1. Gradient factors
In the deco model ZH-L16+GF the gradi-
ent factors (GF) regulate the safety margin
to the maximum values of the Bühlmann
model that should not be exceeded during
deco.
The GF are indicated like this: First the GF
low, then the GF high is specied, for exam-
ple GF 30/85
GF low
The GF low regulates the allowed satu-
ration for the rst deepest decostop. The
smaller the value of the GF low, the deeper
starts the rst deco stop.
Setting range: 10 – 100%
Default: 30%
GF high
The GF high regulates the allowed satura-
tion for the last shallowest decostop. The
smaller the value of the GF high, the longer
is the last deco stop.
Setting range: 45 – 110%
Default: 85%
Alternative GF (aGF)
Settings for an alternative GF pair which
can be toggled while diving. With »aGF se-
lectable: No/Yes« you can set up if the alter-
native GF pair can be toggled while diving
or not. When you select »Yes«, the aGF can
be toggled in the menu in dive mode.
Default: No
aGF low
Alternative value for the GF low in percent.
Setting range: 10 – 100%
Default: 60%
aGF high
Alternative value for the GF high in percent.
Setting range: 45 – 110%
Default: 85%
!Warning
Only change values for decompression cal-
culation if you are aware of their meanings.
The presettings of the deco parameters are
well established and proven. Changes have
direct inuence on the decompression cal-
culation and modify the conservatism of
the Bühlmann model.
4.3.3.2. Saturation factors
The classical Bühlmann model ZH-L16 does
not use GF, but saturation factors to create
a safety margin to the maximum values of
the deco model.
Saturation
Multiplier for saturation process. A value of
100% corresponds to the pure Bühlmann
model without any safety margin (in ZH-
L16). The higher the value, the more an in-
creased saturation will be considered.
Setting range: 100 – 140%
Default: 110% (ZH-L16),
100% (ZH-L16+GF)
Menu overview »deco parameter«.

19
Desaturation
Multiplier for desaturation process. A value
of 100% corresponds to the pure Bühlmann
model without any safety margin (in ZH-
L16). The lower the value, the more a slow-
er desaturation will be considered. Setting
range: 60 – 100%
Default: 90% (ZH-L16), 100% (ZH-L16+GF)
GF + saturation factors
Using the ZH-L16+GF with gradient fac-
tors you can additionally adjust the decom-
pression to the diving conditions with the
saturation factors. A faster saturation be-
cause of increased work can be considered
by a higher value of the saturation factor, a
slower desaturation can be considered by
a lower value of the desaturation factor. If
you don`t want to use the saturation fac-
tors additionally, choose the value 100% for
both factors.
4.3.3.3. Last deco
Setting for the depth of the last decom-
pression stop. Choose here if the OSTC shall
calculate its last stop at 3, 4, 5 or 6 meter.
When you have heavy waves, a deeper last
decostop can be better.
Setting range: 3 – 6 meters
Default: 3 meters
4.3.4. ppO2 settings
Settings for maxium and minimum value
of oxygen partial pressure (ppO2). This val-
ue has an impact on the MOD (maximum
operating depth) during setup gases and
using them.
The minimum threshold Min warns of a too
low oxygen level.
Setting range: 0,16 – 0,21 bar
Default: 0,19 bar
The maximum threshold Max warns of a
too high oxygen level. With Max Deco you
can dene a different value for the deco
phase of a dive.
Setting range: 1,20 – 1,60 bar
Default: 1,40 bar (Max), 1,60 bar (Max
Deco)
With Min Loop rebreather divers can set up
a threshold for a minimum ppO2 level in
their loop.
Setting range: 0,20 – 0,60 bar
Default: 0,40 bar
With Always show you can choose if the
ppO2 shall appear permanently on the dis-
play (otherwise you can see it in the custom
view).
Default: No
You can set up a different ppO2 value for the deco
and for the maximum depth of the dive.

20
4.3.5. Safety stop
The safety stop can be switched on or off.
After a dive within the no deco limit (NDL)
the OSTC shows a safety stop of 3 minutes
in 5 meters. It is displayed as a countdown
split to the second. It will not be displayed
after a deco dive.
Default: No
4.3.6. Second deco plan
In the submenu »2nd deco plan« you can
activate extended and alternative calcula-
tions for the deco and the ascent.
4.3.6.1. Future TTS/Future Bailout
If you set a value greater than zero at fTTS/
fB/O, there will be a deco forecast in dive
mode. In OC mode the future TTS (fTTS)
shows the TTS (total time to surface) that
you will have if you stay for xx minutes (the
set value) on the current depth.
For example: »fTTS @5« shows the TTS that
you will have in ve minutes if you stay on
the current depth.
The future TTS is displayed as soon as a fu-
ture TTS with a decostop is available. In
case of a bailout there will be no fTTS cal-
culation.
Additionally the future value of the CNS
(CNS fTTS) that results from future TTS will
be calculated. In dive mode it is displayed in
the custom view. If the future CNS value ex-
ceeds 100%, there will be a warning.
In CCR mode the fTTS is either applied to
the values of the rebreather (Calculation
Gas B/O: No) or as future bailout to the bail-
out gases (Calculation Gas B/O: Yes).
See next chapter.
Setting range: 0 – 9 minutes
(0 = disabled)
Default: 0 minutes
4.3.6.2. Calculation gas (B/O)
If this option is selected, the dive computer
calculates the gas needs that you need to
nish your dive including all decostops and
the ascent rates. B/O means bailout.
OC mode:
If the Future TTS is deactivated (set to zero),
the dive computer will show you how much
gas you would need if you started the as-
Menu overview »2nd deco plan«.
Future TTS in dive mode: If the diver stays another
5 minutes (@+5) on the current depth, then he will
have a TTS of 26 minutes.