Suunto COBRA User manual

Arrows: - Decompression Stop at the Ceiling Depth - Mandatory Safety Stop Zone - Ascent Recommended - Must Descend
QUICK REFERENCE GUIDE
bar psi
°
F
°C
ft
MAXAVGPO2
NO DEC TIME
STOP
AIR TIME
TIME
SURF
DIVE
O2% ASC TIME
CEILING
OK
QUIT
SELECT
OPTIONS
NO
S
L
O
W
T
C
B
OLF
DIVE
m
°C
bar
Low Battery Warning
Cylinder Pressure Temperature Week Day Mode Text Personal Adjustment Mode Do Not Fly Icon Bar Graph: - Mode Indicator - Consumed Bottom Time
- Oxygen Limit Fraction
Bar Graph: - Ascent Rate Indicator - Battery Power Indicator - Logbook Page Indicator
Present Depth Dive Counter
Plan Button
Scroll Button (increase value, ascend)
Remaining Air Time / Oxygen Percentage in Nitrox Mode
Current Time Display Surface Interval Time No Flying Time No-Decompression Time Total Ascent Time Safety Stop Time Dive Time Time Month,Day The Smart Button: - Activation - Backlight - Mode Operations
Maximum Depth Ceiling Depth on Decompression Stop Mandatory Safety Stop Depth Average Depth in Logbook Oxygen Partial Pressure AM/PM Indicator
Altitude Adjustment Mode Bookmark Symbol
Daily/DiveTime/Depth Alarm
On Indicator
Diver Attention Symbol
Smart Button Indicators
Scroll Button Indicators Time (alternative display) Button
Scroll Button (decrease value, descend)
Fast Ascent Warning (SLOW) Safety Stop Warning Safety Stop Indicator

8
1. INTRODUCTION
Congratulations on your purchase of the SUUNTO COBRA advanced dive
computer. The Cobra builds on the Suunto tradition of delivering feature-rich
dive computers. The Cobra provides many new and enhanced features that
cannot be found in any other air-integrated dive computer. Push button controls
access a wide selection of choices. The display is optimized for the dive mode
chosen. This air-integrated dive computer is a compact and sophisticated
multipurpose dive instrument, designed to give you years of trouble-free service.
CHOICE OF OPERATING MODES AND SET-UP OPTIONS
User options for the Cobra are selected using the push buttons. Pre Dive
configuration and setup options include:
•Choice of operating mode - Air / Nitrox / Gauge
•Choice of unit - Metric / Imperial
•Maximum depth alarm
•Dive time alarm
•Backlight settings
•Clock, calendar, daily alarm
•Mix Oxygen fraction % (Nitrox mode only)
•Maximum PO2(Nitrox mode only)
•Altitude adjustment
•Personal adjustment
CONTINUOUS DECOMPRESSION WITH SUUNTO RGBM
The Suunto Reduced Gradient Bubble Model (RGBM) utilized in the Cobra
predicts both dissolved and free gas in blood and tissues of divers. It is a
significant advance on the classic Haldane models, which do not predict free
gas. The advantage of Suunto RGBM is additional safety through its ability to
adapt to a variety of situations and dive profiles.
In order to optimize how to respond to different added risk situations an
additional category of stop, referred to as a Mandatory Safety Stop, has been
introduced. Also a countdown for the Recommended Safety Stop is included.
The combination of stop types will depend on the specific dive situation.
To get the most from the safety benefits be sure to read the summary of the
Suunto Reduced Gradient Bubble Model on page 62.

9
1.1. SAFETY PRECAUTIONS
Do not attempt to use the dive computer without reading this instruction manual
in its entirety, including all the warnings. Make sure that you fully understand
the use, displays and limitations of the instrument. If you have any questions
about the manual or the dive computer, contact your SUUNTO dealer before
diving with the dive computer.
Always remember that YOU ARE RESPONSIBLE FOR YOUR OWN SAFETY!
When used properly, the dive computer is an outstanding tool for assisting
properly trained, certified divers in planning and executing sport dives. It is
NOT A SUBSTITUTE FOR CERTIFIED SCUBA INSTRUCTION, including
training in the principles of decompression.
Diving with enriched air mixtures (nitrox) exposes the user to risks different
from those associated with diving with standard air. These risks are not obvious
and require training to understand and avoid. Risks include possible serious
injury or death.
Do not attempt to dive with any gas mix other than standard air without first
receiving certified training in this specialty.
1.1.1. EMERGENCY ASCENTS
In the unlikely event that the dive computer malfunctions during a dive, follow
the emergency procedures provided by your certified dive training agency or,
alternatively,
STEP 1: Assess the situation calmly and then move promptly to less than 18 m
[60 ft].
STEP 2: At 18 m [60 ft], slow down your ascent rate to 10 m/min [33 ft/min] and
move to a depth between 3 and 6 meters [10 to 20 ft].
STEP 3: Stay there as long as you assess your air supply will safely allow.
After reaching the surface stay out of the water for at least 24 hours.
1.1.2. DIVE COMPUTER LIMITATIONS
While the dive computer is based on current decompression research and
technology, you must realize that the computer cannot monitor the actual
physiological functions of an individual diver. All decompression schedules
currently known to the authors, including the U.S. Navy Tables, are based on
theoretical mathematical models, which are intended to serve as a guide to
reduce the probability of decompression illness.

10
1.1.3. NITROX
Diving with nitrox provides the diver with an opportunity to reduce the risk of
decompression illness by reducing the nitrogen content in the breathing gas
mix.
However, when the gas mix is altered, the oxygen content of the mix is generally
increased. This increase exposes the diver to an oxygen toxicity risk not usually
considered in recreational diving. In order to manage this risk, the dive computer
tracks the time and intensity of the oxygen exposure and provides the diver
with information to adjust the dive plan in order to maintain oxygen exposure
within reasonably safe limits.
In addition to the physiological effects of enriched air on the body there are
operational considerations to be addressed when handling altered breathing
mixes. Elevated concentrations of oxygen present a fire or explosion hazard.
Consult with the manufacturer of your equipment in regards to its compatibility
with nitrox.

11
2. GETTING ACQUAINTED
2.1. FUNCTIONS
You can select the dive computer model between the Regular Air Dive Computer,
Nitrox Dive Computer and Depth Gauge with Timer mode.
The COBRA multipurpose dive computer is an air integrated computer featuring
three dive computer modes (AIR, NITROX, GAUGE), three main operating
modes (TIME/STAND-BY, SURFACE, DIVING), three menu based main modes
(MEMORY, SIMULATION, SET) and 16 - 18 menu based submodes (review
separate Quick Reference Guide). You can scroll through the modes using the
push buttons. The mode indicator at the left side and the mode text at the
bottom of the display indicate the selected mode.
The timekeeping display is the default display of the instrument (Fig. 2.1.). If a
button is not pressed within 5 minutes, the dive computer beeps and returns to
the timekeeping display automatically (except in Diving and Simulation modes).
The timekeeping display shuts off after two hours, but pressing the PLAN or
TIME button activates it.
2.2. CONNECTINGTHE COBRATOA REGULATOR
Upon purchasing the Cobra, Suunto strongly recommends you have your
dealer attach it to the first stage of your regulator.
If you decide to attach it yourself, follow the steps outlined below:
1. Remove the high pressure (HP) port plug on the first stage of your
regulator using an appropriate sized wrench.
2. Thread the high pressure hose of the Cobra into the port of your
regulator with your fingers. Tighten the hose fitting with a 16 mm
[5/8"] wrench. DO NOT OVERTIGHTEN!
3. Attach the regulator to a charged scuba cylinder. Slowly open the
valve. Check for leaks by submerging the first stage regulator in
water. If leaks are detected, consult your dealer.

12
2.3. PUSH BUTTONS
The dive computer has easy-to-use push buttons and an advisory display,
which guides the user. The SMART (MODE) button is the key to the system.
The two scroll buttons, PLAN and TIME, are used for scrolling up and down
the menus and to show the alternative displays. The dive computer is controlled
with these three push buttons as follows (see Fig. 2.2.).
Press the SMART (MODE) button
•To activate the dive computer.
•To change from the Surface Mode to the menu based modes.
•To select, confirm or quit a submode (short press).
•To immediately exit any submode to the Surface Mode (long press).
•To activate the electroluminescent backlight (in the Surface Mode
hold down the mode button for more than two (2) seconds, during a
dive for one (1) second).
Press the arrow up scroll (PLAN) button
•To activate the timekeeping display, if the display is blank.
•To activate the Dive Planning in the Surface Mode.
•To make a special bookmark in the profile memory during a dive.
•To scroll up the options (L, increase).
Press the arrow down scroll (TIME) button
•To activate the timekeeping display, if the display is blank.
•To activate the Time display(s) and/or alternative display(s).
•To scroll down the options (M, decrease).
The dive computer is controlled with the SMART (MODE/On/Backlight/
Select/OK/Quit) and the PLAN Land TIME Mpush buttons and with the
water contacts as follows:
Activation press the SMART (On) button or immerse the instrument in
water for five (5) seconds.
Dive Planning in the Surface Mode, press the PLAN button.
Menu Modes press the SMART (MODE) button.
The display is illuminated by holding down the SMART button for more than
two seconds.

13
2.4.WATER CONTACTS
The water contacts control the automatic activation
of the Dive Mode.
The water and data transfer contacts are located on
bottom of the case (Fig 2.3.). When submerged the
water contacts are connected to the push buttons
(which are the other pole of the water contact) by the
conductivity of the water. The "AC" text (Active
Contacts, Fig. 2.4.) will appear on display. The AC
text will be shown until the water contact deactivates
or the dive computer enters the Dive Mode
automatically.
Fig. 2.1. Time keeping display.
Pressing PLAN or TIME
button activates display.
Fig. 2.2. Push buttons of the
dive computer.
Fig 2.3. Depth sensor (A),
water/data transfer contacts (B).
Fig. 2.4. Active water contacts
are indicated by the text AC.
A
B
The SMART button
The PLAN, TIME and
SCROLL buttons

14
° F
° C
ft
MAXAVGPO2
NO DEC TIME
STOP
TIME
TIME
SURF
DIVE
O2%
ASC TIME
CEILING
OK
QUIT
SELECT
OPTIONS
NO
S
L
O
W
T
C
B
OLF
DIVE
m
ps
AIR
bar
3. DIVING WITH THE COBRA
This section contains instructions on how to operate
the dive computer and interpret its displays. You will
find that this dive computer is easy to use and read.
Each display shows only the data relevant to that
specific diving situation.
3.1 BEFORE DIVING
3.1.1. ACTIVATION AND PRECHECKS
The dive computer will activate if submerged deeper
than 0.5 m (1.5 ft). However, it is necessary to turn on
the Dive Mode before diving to check the cylinder
pressure, altitude and personal adjustment settings,
battery condition, oxygen settings etc. Press the
SMART (On) button to activate the instrument.
After activation all display elements will turn on
showing mostly figure 8's and graphical elements (Fig.
3.1.). A few seconds later the battery power indicator
is shown and the backlight and the buzzer are
activated (Fig. 3.2. display a, b, c or d depending on
the battery voltage). If set to Air mode the screen will
enter the Surface mode (Fig. 3.3.). If set to Gauge
mode the text GAUGE is shown (Fig. 3.4.) and if set to
Nitrox mode the essential oxygen parameters are
shown with the text NITROX (Fig. 3.21.) before the
Surface mode.
At this time, perform your precheck making sure that:
• the instrument operates in the correct mode
and provides a complete display (Air and
Nitrox modes)
• the low battery indicator is not on
• the altitude and personal adjustment
settings are correct
• the instrument displays correct units of
measurement (Metric/Imperial)
• the instrument displays correct temperature
and depth (0.0 m [0 ft])
• the buzzer beeps
Fig. 3.1. Startup I. All
segments shown.
Fig. 3.2. Startup II. Battery
power indicator.
QUIT
OK
a
b
c
d

15
•you have enough air for your planned dive. You should also check
the pressure reading against your back-up pressure gauge.
And if set to Nitrox mode, make sure that:
•the oxygen percentage is adjusted according to the measured Nitrox
blend in your cylinder
•the oxygen partial pressure limit is set correctly.
The dive computer is now ready for diving.
3.1.2. BATTERY POWER INDICATOR AND LOW
BATTERY WARNING
This dive computer has a unique graphic Battery Power Indicator designed to
give you an advance notice of impending need to change the battery.
The Battery Power Indicator can always be seen when the Dive Mode is
activated. The electroluminescent backlight will be on during the battery check.
The following Table and Figure show the various warning levels.
TABLE 3.1. BATTERY POWER INDICATOR

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TIME
DIVE
m
bar
TIME
DIVE
m
TIME
bar
° C
Fig 3.3. Startup III. Surface
mode. Depth and dive time are
zero and cylinder pressure is
300 bar [4350 psi]. Pressing
TIME button activates
alternative display of
temperature and current time.
Fig. 3.4. Startup IV. Gauge
mode.
Fig. 3.5. Low Battery Warning.
Battery symbol indicates that
the battery is low and battery
replacement is recommended.
Temperature or an internal oxidation of the battery
affects the battery voltage. If the instrument is stored
for a long period, the low battery warning may be
displayed even though the battery has enough
capacity. The low battery warning may also be
displayed at low temperatures, even though the
battery has enough capacity in warmer conditions.
In these cases repeat the battery check procedure.
After battery check the Low Battery Warning is
indicated by the battery symbol (Fig. 3.5.).
If the battery symbol is displayed in the Surface mode
or if the display is faded or weak, the battery may be
too low to operate the dive computer and battery
replacement is recommended.
NOTE! For safety reasons the backlight cannot be
activated when the low battery warning is indicated
by the battery symbol.
3.1.3. DIVE PLANNING [PLAN]
To enter Planning Mode, press the PLAN button at
any time during Surface Mode. After showing the
text "PLAN" (Fig. 3.6.), the display will show the no-
decompression limit for the depth of 9 m [30 ft]. By
pressing the down arrow (M) TIME button, the dive
computer will calculate and show the next deeper no-
decompression limits in 3 m [10 ft] increments ending
at 45 m [150 ft]. By pressing the up arrow (L) PLAN
button, the next shallower depth will be shown again.
The Planning Mode is cancelled by pressing the
SMART (QUIT) button.
NOTE! The Planning mode is disabled in Gauge mode
and in Error mode (see section 3.9. "Error
Conditions").

17
QUIT
DIVE
NO DEC TIME
MAX
Higher Altitude and conservative Personal
Adjustment Modes will shorten the no-
decompression time limits. These limits at different
Altitude and Personal Adjustment Mode selections
are shown in Table 6.1 and 6.2 in section 6.1.
"Operating Principles".
The Planning mode also accounts for the following
information from previous dives:
•any calculated residual nitrogen
•all dive history for the past four days
•oxygen toxicity (Nitrox mode)
The no-decompression times given for different
depths will therefore be shorter than before your first
"fresh" dive.
DIVE NUMBERING SHOWN DURING
DIVE PLANNING
Dives belong to the same repetitive dive series if the
instrument was still counting down the no-fly time at
the beginning of the dive.
The surface interval must be at least 5 minutes for a
dive to be considered a repetitive dive. Otherwise, it
is considered a continuation of the same dive. The
dive number will not change and the dive time will
continue where it left off (see also section 3.6.2. "Dive
Numbering").
3.1.4. USER DEFINABLE FUNCTIONS
AND ALARMS
This Cobra has several User Definable Functions and
depth and time related alarms that you can set
according to your personal preference.
The dive computer model, unit of measurement and
backlight preferences can be set in the MODE- SET-
SET PREF submode. The dive time and the depth
alarms can be set in the MODE- SET- SET DIVE
submode and the alarm clock can be set in the MODE-
SET- SET TIME submode. Setting of the user definable
functions and alarms are explained in detail in section
4.3. "Set Modes".
Fig. 3.6. Dive Planning.
Planning mode is indicated by
PLAN text. No-decompression
time limit at 30.0 m [100 ft] is
14 minutes in A0/P1 mode.

18
3.2. SAFETY STOPS
Safety stops are widely considered "good diving practice" and are an integral
part of most dive tables. Reasons to perform a safety stop include a reduction
in sub clinical DCI, microbubble reduction, ascent control, and orientation
before surfacing.
The Cobra displays two different types of safety stops: Recommended Safety
Stop and Mandatory Safety Stop.
The Safety Stops are indicated by:
•STOP label, when in the depth range 3 m - 6 m [10 ft - 20 ft]
= Recommended Safety Stop Countdown
•STOP + CEILING label, when in the depth range 3 m - 6 m [10 ft - 20 ft]
= Mandatory Safety Stop Time display
•STOP label, when deeper than 6 m
= Mandatory Safety Stop scheduled
3.2.1. RECOMMENDED SAFETY STOP
With every dive over 10 meters the instrument has a three minute countdown
for the recommended safety stop, to be taken in the 3 - 6 meter [10 ft - 20 ft]
range. This is shown with the STOP sign and a three-minute countdown in the
center window instead of the no-decompression time (Fig. 3.11.).
The Recommended Safety Stop, as the name implies, is recommended. If it is
ignored, there is no penalty applied to the following surface intervals and
dives.
3.2.2. MANDATORY SAFETY STOP
When the ascent rate exceeds 12 meters/min [40 ft] momentarily or 10 meters/
min [33ft] continuously the micro-bubble build-up is predicted to be more than
allowed for in the decompression model. The Suunto RGBM calculation model
responds to this by adding a Mandatory Safety Stop to the dive. The time of
this Mandatory Safety Stop will depend on the severity of the ascent rate
excess.
The STOP sign will appear in the display and when you reach the depth zone
between 6 m to 3 m [20 ft to 10] also the CEILING label, ceiling depth and the
calculated Safety Stop time appear in the display. You should wait until the
Mandatory Safety Stop warning disappears (Fig. 3.14.).
The Mandatory Safety Stop time always includes the three minute
Recommended Safety Stop time. The total length of the Mandatory Safety
Stop time depends on the seriousness of the ascent rate violation.

19
You must not ascend shallower than 3 m [10 ft] with the Mandatory Safety Stop
warning on. If you ascend above the Mandatory Safety Stop ceiling, a downward
pointing arrow will appear and a continuous beeping starts (Fig. 3.15.). You
should immediately descend to, or below, the Mandatory Safety Stop ceiling
depth. If you correct this situation at any time during that dive, there are no
affects on the decompression calculations for future dives.
If you continue to violate the Mandatory Safety Stop, the tissue calculation
model is affected and the dive computer shortens the available no-
decompression time for your next dive. In this situation, it is recommended to
prolong your surface interval time before your next dive.

20
m
NO DEC TIME
T
C
B
MAX
DIVE TIME
MAX
bar
AIR TIME
3.3. DIVING IN AIR MODE
3.3.1. BASIC DIVE DATA
The dive computer will remain in the Surface mode at
depths less than 1.2 m [4 feet]. At depths greater than
1.2 m the instrument will go into the Diving mode
(Fig. 3.7.).
All information on the display is labeled (Fig. 3.7. and
3.8.). During a no-decompression stop dive, the
following information will be displayed:
•your present depth in meters [ft]
•the Remaining Air time
•the Altitude Adjustment setting on the left
side of the center window with a wave and
mountain symbols (A0, A1, or A2) (see
Table 3.3.)
•the Personal Adjustment setting on the left
side of the center window with a diver
symbol and + signs (P0, P1, or P2) (see
Table 3.4.)
•the maximum depth during this dive in
meters [ft], indicated as MAX
•the cylinder pressure in bar [or psi]
displayed in the lower left corner
•the elapsed dive time in minutes, shown as
DIVE TIME in the lower right corner
•the available no-decompression time in
minutes in the center window as NO DEC
TIME and as a bar graph on the left side of
the display. It is calculated based on the five
factors described in Section 6.1. "Operating
Principles".
Fig. 3.9. Diving display. Present cylinder pressure is 210 bar [3045 psi]
and remaining air time 41 minutes. Alternative display of current time
and temperature is shown for 5 seconds after pressing TIME button.
Fig. 3.7. Dive has just begun
and no air time is shown. First
estimate of remaining air time
will be shown after 30-60
seconds.
Fig. 3.8. Diving display.
Present depth is 19.3 m [63 ft]
and no-decompression stop time
limit is 23 minutes in A0/P1
mode. Maximum depth during
this dive was 19.8 m [65 ft],
elapsed dive time is 16
minutes.
TIME
DIVE
m
NO DEC TIME
T
C
B
MAX
bar
m
NO DEC TIME
T
C
B
MAX
DIVE TIME
MAX
bar
AIR TIME
TIME
° C

21
DIVE TIME
T
C
B
m
STOP
MAX
AIR TIME
bar
m
NO DEC TIME
T
C
B
MAX
DIVE TIME
AIR TIME
bar
m
NO DEC TIME
T
C
B
MAX
DIVE TIME
bar
AIR TIME
Alternative displays by pressing the TIME button
(Fig. 3.9.):
•the current time, shown as TIME
•the water temperature followed by °C for
Centigrade [or °F for Fahrenheit].
NOTE! In Dive Mode the TIME / TEMPERATURE
display automatically changes back to DIVE TIME /
CYLINDER PRESSURE after 5 seconds.
3.3.2. BOOKMARK
It is possible to make special marks in the profile
memory during a dive. These Bookmarks will be shown
as a dive log symbol when scrolling the profile memory
on the computer display. The Bookmarks will also be
shown as annotations in the PC-software, Suunto
Dive Manager. To make a bookmark on the profile
memory during a dive press the PLAN button (Fig.
3.10.).
3.3.3. CYLINDER PRESSURE DATA
The air pressure of your scuba cylinder in bars [psi]
will be shown digitally in the lower left corner of the
display. Anytime you enter into a dive, the remaining
air time calculation begins. After 30 - 60 seconds
(sometimes more, depending on your air
consumption), the first estimation of remaining air
time will be shown in the left center window of the
display. The calculation is always based on the actual
pressure drop in your cylinder and will automatically
adapt to your cylinder size and current air
consumption.
The change in your air consumption will be based on
constant one second interval pressure measurements
over 30 - 60 second periods. An increase in air
consumption will influence the remaining air time
rapidly, while a drop in air consumption will increase
the air time slowly. Thus a too optimistic air time
estimation, caused by a temporary drop in air
consumption, is avoided.
Fig. 3.10. Bookmark activation.
An annotation, Bookmark, is
placed in the profile memory
during a dive by pressing PLAN
button. Note Logbook symbol.
Fig. 3.12. Cylinder pressure
warnings. Pressure has dropped
below 50 bar [725 psi]. Pressure
display is blinking and there is
an audible alarm.
Fig. 3.11. A three minute
Recommended Safety Stop.

22
T
C
B
m
STOP
CEILING
DIVE TIME
AIR TIME
bar
DIVE TIME
T
C
B
m
CEILING
STOP
MAX
TIME
AIR TIME
bar
° C
DIVE TIME
T
C
B
m
MAX
S
L
O
W
NO DEC TIME
STOP
AIR TIME
bar
The remaining air time calculation includes a 35
bar [500 psi] safety reserve. This means that when
the instrument shows the air time to be zero, there
is still about 35 bar [500 psi] pressure left in your
cylinder depending on your air consumption rate.
With a high consumption rate the limit will be close
to 50 bar [725 psi] and with a low rate close to 35
bar [500 psi].
NOTE! Filling your BC will affect the air time
calculation, due to the temporary increase in air
consumption.
NOTE! A change of temperature will affect the
cylinder pressure and consequently the air time
calculation.
LOW AIR PRESSURE WARNINGS
The dive computer will warn you with three audible
double beeps and a blinking pressure display
when the cylinder pressure reaches 50 bar [725
psi] (Fig. 3.12.). The next three double beeps are
heard when the cylinder pressure reaches 35 bar
[500 psi] and when the remaining air time reaches
zero.
Fig. 3.13. Ascent Rate
Indicator. Blinking depth
reading, SLOW and four
segments are shown together
with an audible alarm: ascent
rate is more than 10 m/min [33
ft/min]. This is a caution to
slow down! STOP sign means
that you are advised to make a
Mandatory Safety Stop when
you reach a depth of 6 m [20 ft].
Fig. 3.14. A Mandatory Safety
Stop. You are advised to make a
Mandatory Safety Stop in the
depth zone between 6 m and 3
m [20 ft and 10 ft]. Pressing
TIME button shows alternative
display.
Fig. 3.15. Violated Mandatory Safety Stop. Downward
pointing arrow and an audible alarm indicate you should
descend to ceiling zone.

23
3.3.4. CONSUMED BOTTOM TIME (CBT)
The available no-decompression stop time is also shown visually in the multi-
function bar graph on the left side of the display (Fig. 3.7., 3.8. and 3.9.). When
your available no-decompression time decreases below 200 minutes, the first
(lowest) bar graph segment appears. As your body absorbs more nitrogen,
more segments start to appear.
Green Zone - As a safety precaution Suunto recommends you should maintain
the no-decompression bar graph within the green zone. Segments start to
appear when the available no-decompression time decreases below 100, 80, 60,
50, 40, 30 and 20 minutes.
Yellow Zone - As the bars reach the yellow zone, your no-decompression stop
time is less than 10 or 5 minutes and you are getting very close to no-
decompression limits. At this point, you should start your ascent towards the
surface.
Red Zone - As all of the bars appear (red zone), your no-decompression stop
time has become zero and your dive has become a decompression stop dive
(for more information see section 3.3.6. "Decompression dives").
3.3.5. ASCENT RATE INDICATOR
The ascent rate is shown graphically along the right side of the display as
follows:
TABLE 3.2. ASCENT RATE INDICATOR

24
When the maximum allowed ascent rate is exceeded, the fifth SLOW warning
segment and the STOP sign appear and the depth reading starts to blink,
indicating that the maximum ascent rate has been exceeded continuously or
that the current ascent rate is significantly above the allowed rate.
Whenever the SLOW warning segment and the STOP sign appear (Fig. 3.13.),
you should immediately slow down your ascent. When you reach the depth
zone between 6 m to 3 m [20 ft to 10 ft] the STOP and CEILING depth labels will
advise you to make a Mandatory Safety Stop. Wait until the warning disappears
(Fig. 3.14.).You should not ascend shallower than 3 m [10 ft] with the Mandatory
Safety Stop warning on.
WARNING!
DO NOT EXCEED THE MAXIMUM ASCENT RATE! Rapid ascents increase
the risk of injury. You should always make the Mandatory and Recommended
Safety Stops after you have exceeded the maximum recommended ascent
rate. If this Mandatory Safety Stop is not completed the decompression
model will penalize your next dive(s).
3.3.6. DECOMPRESSION DIVES
When your NO DEC TIME becomes zero, your dive becomes a decompression
stop dive, i.e. you must perform one or several decompression stops on your
way to the surface. The NO DEC TIME on your display will be replaced by an
ASC TIME notation and the maximum depth will be replaced by a CEILING
notation and an upward pointing arrow (Fig. 3.16.).
If you exceed the no-decompression limits on a dive, the dive computer will
provide decompression information required for ascent. After this, the
instrument will continue to provide subsequent interval and repetitive dive
information.
Rather than requiring you to make stops at fixed depths, the dive computer lets
you to decompress within a range of depths (Continuous Decompression).

25
The ascent time (ASC TIME) is the minimum amount of time needed to reach
the surface in a decompression dive. It includes:
•the time needed to ascend to the ceiling at an ascent rate of 10 m/min
[33 ft/min] plus
•the time needed at the ceiling. The ceiling is the shallowest depth to
which you should ascend plus
•the time needed at the Mandatory Safety Stop (if any) plus
•the 3 minute Recommended Safety Stop plus
•the time needed to reach the surface after the ceiling and safety stops
have been completed.
WARNING!
YOUR ACTUAL ASCENT TIME MAY BE LONGER THAN DISPLAYED
BY THE INSTRUMENT! The ascent time will increase if you:
- remain at depth
- ascend slower than 10 m/min [33 ft/min] or
- make your decompression stop deeper than at the ceiling.
These factors will also increase the amount of air required to reach the
surface.
CEILING, CEILING ZONE, FLOOR AND DECOMPRESSION
RANGE
When in decompression, it is important that you understand the meaning of
ceiling, floor, and decompression range (Fig. 3.20.):
•The ceiling is the shallowest depth to which you should ascend
when in decompression. At this depth, or below, you must perform
all stops.
•The ceiling zone is the optimum decompression stop zone. It is the
zone between the minimum ceiling and 1.8 m [6 ft] below the minimum
ceiling.
•The floor is the deepest depth at which the decompression stop time
will not increase. Decompression will start when you pass this depth
during your ascent.
•The decompression range is the depth range between the ceiling and
floor. Within this range, decompression takes place. However, it is
important to remember that the decompression will be very slow at,
or close to, the floor.

26
DIVE TIME
T
C
B
m
STOP
CEILING
ASC TIME
MAX
TIME
AIR TIME
bar
° C
DIVE TIME
T
C
B
m
CEILING
ASC TIME
AIR TIME
bar
DIVE TIME
T
C
B
m
CEILING
ASC TIME
AIR TIME
bar
AIR TIME AIR TIME AIR TIME AIR TIME
Fig. 3.16. Decompression dive,
below floor. Upward pointing
arrow, blinking ASC TIME
label and an audible alarm tell
you to ascend. Minimum total
ascent time including safety
stop is 7 minutes. Ceiling is at
3 m [10 ft].
Fig. 3.17. Decompression dive,
above floor. Upward pointing
arrow has disappeared and ASC
TIME label has stopped
blinking, which means that you
are in the decompression range.
Fig. 3.18. Decompression dive, at ceiling zone. Two arrows
point at each other ("hour glass"). You are in the optimum
ceiling zone at 3.5 m [11 ft] and your minimum ascent time
is 5 minutes. Pressing TIME button activates alternative
display.
The depth of the ceiling and floor will depend on
your dive profile. The ceiling depth will be fairly
shallow when you enter the decompression mode,
but if you remain at depth, it will move downward and
the ascent time will increase. Likewise, the floor and
ceiling may change upwards while you are
decompressing.
When conditions are rough, it may be difficult to
maintain a constant depth near the surface. In this
case it will be more manageable to maintain an
additional distance below the ceiling, to make sure
that the waves do not lift you above the ceiling.
Suunto recommends that decompression takes place
deeper than 4 m [13 ft], even if the indicated ceiling is
shallower.
NOTE! It will take more time and more air to
decompress below the ceiling than at the ceiling.
WARNING!
NEVERASCENDABOVETHE CEILING!You must
not ascend above the ceiling during your
decompression. In order to avoid doing so by
accident, you should stay somewhat below the
ceiling.
DISPLAY BELOW THE FLOOR
The blinking ASC TIME and an upward pointing
arrow indicate that you are below the floor (Fig. 3.16.).
You should start your ascent immediately. The ceiling
depth is shown on the right top corner and the
minimum total ascent time on the right side of the
center window.