Suunto COBRA User manual

SUUNTO
COBRA
EN
USER’S GUIDE

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

1
DEFINITION OF WARNINGS, CAUTIONS AND NOTES
Throughout this manual, special references are made when deemed important. Three
classifications are used to separate these references by their order of importance.
WARNING is used in connection with a procedure or situation that
may result in serious injury or death.
CAUTION is used in connection with a procedure or situation that
will result in damage to the product.
NOTE is used to emphasize important information.
COPYRIGHT, TRADEMARK AND PATENT NOTICE
This instruction manual is copyrighted and all rights are reserved. It may not, in whole
or in part, be copied, photocopied, reproduced, translated, or reduced to any media
without prior written consent from SUUNTO.
SUUNTO, COBRA, Consumed Bottom Time (CBT), Oxygen Limit Fraction (OLF),
SUUNTO Reduced Gradient Bubble Model (RGBM), Continuous Decompression
and their logos are all registered or unregistered trademarks of SUUNTO. All rights
are reserved.
Patents have been issued or applied for one or several features of this product.
CE
The CE mark is used to mark conformity with the European Union EMC
directive 89/336/EEC. The SUUNTO dive instruments fulfill all the required EU
directives.
FIOH, Laajaniityntie 1, FIN-01620 Vantaa, Finland, notified body no.0430, has
EC type-examined this type of personal protective equipment.
EN 250 Respiratory equipment - Open circuit self-contained compressed air diving
apparatus - Requirements, testing, marking.
The tank pressure gauge and the parts of this product used in measuring the tank
pressure meet the requirements set in the section of the European Standard EN 250
that concern tank pressure measurements. The instruments must be serviced by an
authorized dealer every second year or after 200 dives (whichever comes first).
PrEN 13319
PrEN 13319 “Diving accessories - Depth gauges and combined depth and time
measuring devices - Functional and safety requirements, test methods” is a
European diving depth gauge standard draft. The COBRA is designed to comply
with this draft standard.
ISO 9001
SUUNTO Oyj’s Quality Assurance System is certified by Det Norske Veritas to be
according to the ISO 9001 in all SUUNTO Oyj’s operations (Quality Certificate No.
96-HEL-AQ-220).

2
WARNINGS
SUUNTO Oyj does not assume any responsibility for losses or claims by third
parties, which may arise through the use of this device.
Due to continuous product development, the COBRA is subject to change without
notice.
WARNING!
READ THIS MANUAL! Carefully read this instruction manual in its entirety
paying close attention to all warnings listed below, including section 1.1. “Safety
Precautions”. Make sure that you fully understand the use, displays and limitations
of the dive computer because any confusion resulting from neglecting to follow
this instruction manual or from improper use of this device may cause a diver to
commit errors that may lead to serious injury or death.
WARNING!
NOT FOR PROFESSIONAL USE! Suunto dive computers are intended for
recreational use only. The demands of commercial or professional diving
may expose the diver to depths and exposures that tend to increase the risk of
decompression illness (DCI). Therefore, Suunto strongly recommends that the
device be not used for commercial or professional diving activity.
WARNING!
ONLY DIVERS TRAINED IN THE PROPER USE OF SCUBA DIVING
EQUIPMENT SHOULD USE A DIVE COMPUTER! No dive computer can
replace the need for proper dive training. Insufficient or improper training may
cause diver to commit errors that may lead to serious injury or death.
WARNING!
THERE IS ALWAYS A RISK OF DECOMPRESSION ILLNESS (DCI) FOR ANY
DIVE PROFILE EVEN IF YOU FOLLOW THE DIVE PLAN PRESCRIBED
BY DIVE TABLES OR A DIVE COMPUTER. NO PROCEDURE, DIVE
COMPUTER OR DIVE TABLE WILL PREVENT THE POSSIBILITY OF DCI
OR OXYGEN TOXICITY! An individual’s physiological make up can vary from
day to day. The dive computer cannot account for these variations.You are strongly
advised to remain well within the exposure limits provided by the instrument to
minimize the risk of DCI. As an added measure of safety, you should consult a
physician regarding your fitness before diving.

3
WARNING!
SUUNTO STRONGLY RECOMMENDS THAT SPORT DIVERS LIMIT THEIR
MAXIMUM DEPTH TO 40 M [130 FT] OR TO THE DEPTH CALCULATED
BY THE COMPUTER BASED ON THE SELECTED O2% AND A MAXIMUM
PO2 OF 1.4 BAR SETTINGS!
WARNING!
DIVES WITH REQUIRED DECOMPRESSION STOPS ARE NOT
RECOMMENDED.YOU SHOULD ASCEND AND BEGIN DECOMPRESSION
IMMEDIATELY WHEN THE DIVE COMPUTER SHOWS YOU THAT A
DECOMPRESSION STOP IS REQUIRED! Note the blinking ASC TIME symbol
and the upward pointing arrow.
WARNING!
USE BACK-UP INSTRUMENTS! Make sure that you use back-up instrumentation
including a depth gauge, submersible pressure gauge, timer or watch, and have
access to decompression tables whenever diving with the dive computer.
WARNING!
PERFORM PRECHECKS! Always activate and check the device before diving
in order to ensure that all Liquid Crystal Display (LCD) segments are completely
displayed, that the device has not run out of battery power, and that the oxygen,
altitude and personal adjustments are correct. Also, exit the Data Transfer mode
before diving, as the computer does not automatically revert to Dive mode from
Data Transfer mode.
WARNING!
YOU ARE ADVISED TO AVOID FLYING ANY TIME THE COMPUTER
COUNTS DOWN THE NO-FLYING TIME. ALWAYS ACTIVATE THE
COMPUTER TO CHECK THE REMAINING NO-FLY TIME PRIOR TO
FLYING! The computer goes into the stand-by display automatically 5 minutes
after the dive has ended. The stand-by display shuts off after two hours. Flying
or traveling to a higher altitude within no-fly time can greatly increase the risk
of DCI. Review the recommendations given by Diver’s Alert Network (DAN) in
chapter 3.6.3. “Flying After Diving”. There can never be a flying after diving rule
that is guaranteed to completely prevent decompression illness!

4
WARNING!
THE DIVE COMPUTER SHOULD NEVER BE TRADED OR SHARED
BETWEEN USERS WHILE IT IS IN OPERATION! Its information will not
apply to someone who has not been wearing it throughout a dive or sequence of
repetitive dives. Its dive profiles must match that of the user. If it is left on the
surface during any dive, it will give inaccurate information for subsequent dives.
No dive computer can take into account dives made without the computer. Thus
any diving activity up to four days prior to initial use of the computer may cause
misleading information and must be avoided.
WARNING!
DO NOT EXPOSE THE COBRA DIVE COMPUTER WITH IT´S STANDARD
HOSE TO ANY GAS MIX CONTAINING MORE THAN 40% OXYGEN!
Enriched air with greater oxygen content presents a risk of fire or explosion and
serious injury or death.
WARNING!
DO NOT DIVE WITH A CYLINDER OF ENRICHED AIR IF YOU HAVE NOT
PERSONALLY VERIFIED ITS CONTENTS AND ENTERED THE ANALYZED
VALUE INTOYOUR DIVE COMPUTER! Failure to verify cylinder contents and
enter the appropriate O2% into your dive computer will result in incorrect dive
planning information.
WARNING!
THE DIVE COMPUTER WILL NOT ACCEPT FRACTIONAL PERCENTAGE
VALUES OF OXYGEN CONCENTRATION. DO NOT ROUND UP
FRACTIONAL PERCENTAGES! For example, 31.8% oxygen should be entered
as 31%. Rounding up will cause nitrogen percentages to be understated and will
affect decompression calculations. If there is a desire to adjust the computer to
provide more conservative calculations, use the personal adjustment feature to affect
decompression calculations or reduce the PO2setting to affect oxygen exposure.
WARNING!
SET THE CORRECT ALTITUDE ADJUSTMENT MODE! WHEN DIVING at
altitudes greater than 300 m [1000 ft] the Altitude Adjustment feature must be
correctly selected in order for the computer to calculate the decompression status.
THE DIVE COMPUTER is not intended for use at altitudes greater than 3000
m [10000 ft]. FAILURE TO SELECT the correct Altitude Adjustment setting or
diving above the maximum altitude limit will result in erroneous dive and planning
data.

5
WARNING!
SET THE CORRECT PERSONAL ADJUSTMENT MODE!, Whenever it
is believed that factors that tend to increase the possibility of DCI exist, it is
recommended that you use this option to make the calculations more conservative.
Failure to select the correct Personal Adjustment setting will result in erroneous
dive and planning data.
NOTE!
It is not possible to change between Air, Nitrox and Gauge modes before the
instrument has counted down the no-flying time.
There is one exception to this: You can change from Air to Nitrox mode even
during the no-flying time. When planning both air and nitrox dives during the
same dive series, you should set the instrument in Nitrox mode and modify the
gas mix accordingly.
In Gauge mode, the no-flying time is always 48 hours.

6
TABLE OF CONTENTS
WARNINGS .................................................................................... 1
1. INTRODUCTION ....................................................................... 8
1.1. SAFETY PRECAUTIONS.........................................................................9
1.1.1. Emergency Ascents....................................................................9
1.1.2. Dive Computer Limitations .......................................................9
1.1.3. Nitrox .......................................................................................10
2. GETTING ACQUAINTED........................................................ 11
2.1. FUNCTIONS............................................................................................11
2.2. CONNECTING THE COBRA TO A REGULATOR ..............................11
2.3. PUSH BUTTONS ....................................................................................12
2.4. WATER CONTACTS ...............................................................................13
3. DIVING WITH THE COBRA................................................... 14
3.1. BEFORE DIVING....................................................................................14
3.1.1. Activation and Prechecks.........................................................14
3.1.2. Battery Power Indicator and Low Battery Warning.................15
3.1.3. Dive Planning [PLAN] ............................................................16
3.1.4. User Definable Functions and Alarms .....................................17
3.2. SAFETY STOPS ......................................................................................18
3.2.1. Recommended Safety Stop......................................................18
3.2.2. Mandatory Safety Stop ............................................................18
3.3. DIVING IN AIR MODE ..........................................................................20
3.3.1. Basic Dive Data .......................................................................20
3.3.2. Bookmark.................................................................................21
3.3.3. Cylinder Pressure Data ............................................................21
3.3.4. Consumed Bottom Time (CBT)...............................................23
3.3.5. Ascent Rate Indicator...............................................................23
3.3.6. Decompression dives ...............................................................24
3.4. DIVING IN NITROX MODE..................................................................28
3.4.1. Before Diving...........................................................................28
3.4.2. Oxygen Displays......................................................................29
3.4.3. Oxygen Limit Fraction (OLF) .................................................30
3.5. DIVING IN GAUGE MODE...................................................................31
3.6. AT THE SURFACE ..................................................................................32
3.6.1. Surface Interval........................................................................32
3.6.2. Dive Numbering.......................................................................33
3.6.3. Flying After Diving..................................................................34
3.7. AUDIBLE AND VISUAL ALARMS................................................35
3.8. HIGH ALTITUDE DIVES AND PERSONAL ADJUSTMENT ......37
3.8.1. Altitude Adjustment .................................................................37
3.8.2. Personal Adjustment ................................................................38
3.9. ERROR CONDITIONS ...........................................................................39

7
4. MENU BASED MODES........................................................... 40
4.1. MEMORIES AND DATA TRANSFER [1 MEMORY]...........................42
4.1.1. Logbook and Dive Profile Memory [1 LOGBOOK]...............42
4.1.2. Dive History Memory [2 HISTORY].......................................45
4.1.3. Data Transfer and PC-Interface [3 TR-PC]..............................45
4.2. SIMULATION MODE [2 SIMUL]..........................................................47
4.2.1. Dive Simulator [1 SIMDIVE]..................................................47
4.2.2. Dive Planning Simulator [2 SIMPLAN]..................................48
4.3. SET MODES [3 SET] ..............................................................................49
4.3.1. Dive Parameter Settings [1 SET DIVE] ..................................49
4.3.1.1. Altitude Adjustment and Personal Adjustment Settings
[1 AdJ MODE]........................................................................49
4.3.1.2. Dive Time Alarm Setting [2 d ALARM]....................50
4.3.1.3. Maximum Depth Alarm Setting [3 MAX DPTH] .....50
4.3.1.4. Nitrox/Oxygen Settings [4 NITROX] ........................50
4.3.2. Setting Time [2 SET TIME].....................................................51
4.3.2.1. Adjusting Time [1 AdJ TIME]....................................51
4.3.2.2. Adjusting Date [2 AdJ DATE]....................................51
4.3.2.3. Adjusting Daily Alarm [3 T ALARM] .......................51
4.3.3. Setting Preferences [3 SET PREF] ..........................................52
4.3.3.1. Backlight Setting [1 LIGHT] .....................................52
4.3.3.2. Dive Computer Units Setting [2 UNITS]...................52
4.3.3.3. Dive Computer Model Setting [3 MODEL] -
AIR/NITROX/GAUGE ..............................................52
5. CARE AND MAINTENANCE ................................................. 53
5.1. IMPORTANT INFORMATION ...............................................................53
5.2. CARE OF YOUR DIVE COMPUTER.....................................................54
5.3. MAINTENANCE .....................................................................................55
5.4. WATER RESISTANCE INSPECTION....................................................55
5.5. BATTERY REPLACEMENT ...................................................................55
5.6. DISPLAY SHIELD REPLACEMENT.....................................................59
5.7. COMPASS ATTACHMENT.....................................................................59
6. TECHNICAL DESCRIPTION .................................................. 60
6.1. OPERATING PRINCIPLES.....................................................................60
6.2. REDUCED GRADIENT BUBBLE MODEL, SUUNTO RGBM ...........62
6.3. OXYGEN EXPOSURE............................................................................63
6.4. TECHNICAL SPECIFICATION..............................................................64
7. WARRANTY ............................................................................. 67
8. GLOSSARY ............................................................................... 68

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. CONNECTING THE COBRA TO A 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 regula-
tor 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 (s, 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 (t, decrease).
The dive computer is controlled with the SMART (MODE/On/Backlight/Select/
OK/Quit) and the PLAN sand TIME tpush 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), wa-
ter/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
psi
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

16
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 alterna-
tive display of temperature and
current time.
TIME
DIVE
m
TI
M
bar
° C
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 (t) 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 (s) 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. Plan-
ning 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.
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