Cochran GEMINI User manual

www.divecochran.com
Cochran
GEMINI
With
Monitor WU
Owner’s Manual
English –Imperial
Ver: Gemini.Mon.1.50
Manual Part Number: 4300812
For your records, please fill in the following:
Serial Number of the Tank Unit: _______________________________
Serial Number of the Wrist Unit: _______________________________
Your Name: _______________________________________________
Your Contact: _____________________________________________
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Purchase Date: ____________________________________________
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Product Introduction: Your GEMINI Dive Computer from Cochran Undersea Technology
is one of the most advanced instruments made for this application. The GEMINI consists of
two component parts, the Tank Unit (TU) and the Wrist Unit (WU), the TU contains the High
Pressure Transducer Assembly, Depth/Altitude Sensor, and the computer‟s electronics.
The TU performs the time-depth calculations and is where the detailed dive statistics and
profiles are stored. The GEMINI incorporates more user-programmable functions than any
other dive computer made, yet is one of the simplest to use. You may enter personal
preferences, dive site, and condition-specific settings. The GEMINI calculates these factors
in the background, displaying to you, the diver, the critical information you need, in an easy
to comprehend display. The GEMINI computers are one of the first dive computers to
implement a Training Mode, which enables the computer to record and store data in
shallow water training environments (swimming pools, shallow lakes, etc.). To get the
safest and most effective use of this instrument, it is important that the user fully
understand the product. Please read and understand this entire manual and know the
principles and practice safe diving before using this device. By using the GEMINI, the diver
specifically acknowledges that he has been adequately and thoroughly trained and certified
to engage in diving by a professional, competent, recognized training agency.
This Manual is divided into the following Sections:
Section Page
Operation as an Air/Single Blend Nitrox Dive Computer 1
Clock Operation 13
Touch Programming 13
Warnings 24
Oxygen & PO2 factors 26
Gas Blend Switching 28
Constant PO2 Operation 35
Configurable Items 49
Specifications and Maintenance 50
Liability, and Warranty 59
Itemized Index and Subjects 64
INSTALLATION: The Tank Unit (TU) high-pressure sensor installs into a high-pressure
port of your first-stage regulator. Your Authorized Dealer should do this at the time of
purchase. Should you choose to install the TU yourself:
1. Remove your current high-pressure hose or the high-pressure plug from your
first stage regulator.
2. Lightly lubricate the sensor O-ring only with a lubricant approved for use with
Enriched Air Nitrox equipment. DO NOT USE SILICONE GREASE.
3. Screw the sensor, HAND TIGHT, into the first-stage high-pressure port
4. Using a Scuba Tool, or thin 9/16" open-end wrench, snug the high-pressure
transducer connection taking caution to not over tighten.
CAUTION: DO NOT use tools such as vise-grips or channel lock pliers.
These tools can damage the transducer and such damage is not covered by
the limited warranty.
CAUTION: DO NOT use your hand to tighten the high-pressure connection.
This procedure should only be accomplished by using the appropriate tool
placed over the metal nut of the high-pressure connection. It must not be
over tightened.

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With the first stage properly attached to a filled SCUBA cylinder, slowly open the cylinder
valve. Once the valve has been opened, listen to the TU‟s high-pressure connection for
any escaping gas. If possible, completely immerse the tank and regulator in water to see if
bubbles form around your connection. If any gas leak is seen or heard, immediately turn
the gas off by closing the cylinder valve and take the entire regulator system to the place
where you purchased your GEMINI.
The Tank Unit (TU) clips to a low-pressure hose close to the first-stage, it is recommended
that the TU be located on the divers left side. When clipping the TU onto the low-pressure
hose, a rolling motion will provide better results rather than pushing the TU straight down
onto the hose. The Wrist Unit (WU) may be worn on the wrist or attached to your
Buoyancy Control Device with the optional retractor.
Figure 49
Tank Unit Touch Contacts
TANK UNIT TOUCH CONTACTS: The Contacts are used to let the user command the
unit to do a number of functions, communicate with a PC for extracting information or
configuring the unit, and determining water conductivity. When Contacts 1 & 2 are shorted,
the GEMINI TU can detect the difference between wet fingers, metal objects, fresh water,
salt water, and a PC interface cable.

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TURNING ON THE GEMINI TU: The TU will automatically activate when it senses a
cylinder pressure greater than 200 psi. Bridging touch Contacts 1 and 2, which are located
on the underside of the tank unit (see Figure 51), with wetted fingers for two seconds will
manually activate it also.
NOTE: If the TU is activated by cylinder pressure it will issue three beeps, if it is activated
by the touch contacts it will issue five beeps.
WRIST UNIT SIDE CONTACTS:
CONTACT #2
CONTACT #1
CONTACT #3
The Contacts are used to let the user command the unit to do a number of functions, or
obtain information and/or configuring the unit. When Contacts 1 & 2 are shorted, the
GEMINI WU can detect the difference between wet fingers, metal objects and water.
TURNING ON THE GEMINI WU: Although the GEMINI WU automatically turns on when it
is submerged in water, it is STRONGLY recommended that wetting two fingers and
simultaneously touching Contacts 1 and 2 for two seconds manually power the unit up.
This allows the diver to ensure that the unit is operating correctly and has adequate battery
capacity prior to entry. The WU will receive information from the TU from approximately 48
inches; the actual distance will vary depending on the orientation of the WU to the TU.
Once activated and in communications with the TU, the unit will remain on until the TU
turns off, usually 60 minutes. When the WU is beyond the communication range of the TU
the WU‟s display will flash. When the WU is back in communication with the TU the display
will cease flashing. Notice that when Contacts 1 & 2 is first bridged, a short beep is issued
which indicates that the unit is recognizing the touch. If the WU is activated and not in
communications with the TU, it will turn off after 15 minutes.
The GEMINI WU will not turn on if the battery voltage is less than 2.0 volts, or a fault is
detected during the self-test.
Bridging the wrist units touch contacts one can activate the WU and two with wetted
fingers. While the WU will activate upon entering the water it is highly recommended that
the WU be turned on manually as part of the divers pre-dive check.

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As the GEMINI WU & TU first recognize a turn-on command, it begins a “Diagnostic”
function where many aspects of the system will be exercised and tested. This procedure
takes about five seconds and an audible beep is issued each second as certain tests are
successfully completed. During this time, all of the segments in the display are turned on
so that the user can confirm their operability. Should a test indicate a malfunction or
marginal test, the unit will turn back off again. The user should ensure that all of the display
segments are on and operating correctly.
CAUTION: After the WU is activated the “SERVICE” legend will be illuminated, this
indicates that the WU‟s memory is being updated with information from the
Tank Unit. It may take several minutes for this process to be completed. A dive
should not be started while the “SERVICE” legend is illuminated.
TURNING OFF THE GEMINI: After the Post Dive Interval following a dive, the GEMINI TU
will remain on for one hour before automatically entering its "Sleep Mode". During the
Sleep Mode, all calculations continue but the display is off. This is a power saving feature
of the GEMINI. The unit will continue calculating Surface Interval, compartment off gassing
as required, and any changes in altitude as it affects Nitrogen Loading. The current
Surface Interval and PreDive Predictions can be viewed by reactivating the units.
You cannot manually turn the TU off. The TU will turn off:
1. After 60 minutes if no tank pressure is sensed and no dive is made.
2. After all 16 half-time compartments are completely off-gassed on repetitive dives.
NOTE: The GEMINI TU will not enter the sleep mode or turn off as long as cylinder
pressure is being applied to the TU.
You cannot manually turn the WU off. The WU will turn off:
1. After 15 minutes after the TU and no dive is made.
2. If in a dive and the WU looses communications with the TU permanently. The WU
will turn off 60 minutes after the lose of communications. The touch Contacts are
disabled during this time.
MAIN GEMINI OPERATING MODES:
Surface Interval (No Nitrogen Residual)
Surface Interval (With Nitrogen Residual)
Dive Mode (Normal No Deco)
Decompression Mode
Post Dive Interval
Touch Programming
SURFACE INTERVAL –AIR ONLY/SINGLE GAS NITROX:

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After completion of the Self-Diagnostic mode or after the Post Dive Interval following a dive,
the GEMINI enters the Surface Interval. This period has two screens, a Primary and an
Alternate. To switch to the Alternate Screen just tap once firmly on the face of the unit.
The Primary Screen displays, if applicable; current Surface Time, the previous dive‟s
Maximum Depth, the Current FO2 (normal Blend) oxygen percentage, Cylinder Pressure,
Gas Supply Time, Current Gas Consumption, and Altitude. The Alternate Screen displays
the previous dive‟s Bottom Time, Dive of Day number; current Time to Fly, current
calculated CNS and OTU value bar graphs. Figure 2 & 2a shows the display with no
residual Nitrogen (a clean Dive). Figure 4 & 4a shows the display with residual Nitrogen (a
repetitive dive). Figure 3 shows the alternate screen with no residual Nitrogen and Figures
5 & 5a with residual nitrogen.

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The “Blend Identifier” displays the Oxygen percentage that the computer is using in its no-
decompression / decompression calculations. When the unit is on the surface it will display
„OF21‟ to indicate that the computer is calculating out-gassing using normal (Normonic) air
(21%).
“Surface Time” starts at zero after a dive and begins counting minutes. If the computer
shuts off and is turned on with Nitrogen residual left, the Surface Time continues to count.
If the computer shuts off and is turned on with no Nitrogen residual left, the Surface Time
will be zero.
“Dive of Day” starts at zero and increments after each dive regardless of the calendar day.
When there is no remaining Nitrogen residual, the Dive of Day is set to zero and the
computer is referred to as a „clean‟ system.
“Time to Fly” is displayed as the number of hours remaining until the nitrogen residual
reaches zero plus a twelve-hour safety factor. Flying is not recommended until Time to Fly
reaches zero.
“Barometric Altitude” is indicated in six ranges via the Ascent Rate Bar Graph as follows
(Altitude compensation is seamless up to 15,000 feet above sea level). The six ranges are
for display purposes only: The GEMINI actually senses and computes extremely small
altitude changes and hence, is called “Seamless”. The term “Barometric Altitude” is used
instead of just “Altitude” because the GEMINI measures Barometric Pressure to determine
Altitude. Barometric Altitude can vary from actual Altitude by over +/- 1000 feet! What is
important to the body when diving is Barometric Altitude.
0 Bars sea level to 2,500 feet 1 Bar 2,500 to 5,000 feet
2 Bars 5,000 to 7,500 feet 3 Bars 7,500 to 10,000 feet
4 Bars 10,000 to 12,500 feet 5 Bars 12,500 to 15,000 feet

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The altitudes indicated are for reference only.
They do not appear on the WU display.
DIVE MODE –AIR ONLY/SINGLE GAS NITROX:
Whether in the Surface Mode, PreDive Prediction Mode, Programming Mode or the
Logbook Mode, The GEMINI will automatically enter the Subsurface Mode when the dive
computer senses a depth greater than five feet and is exited when the dive computer
senses a depth less than five feet.
NOTE: Remember, do not start a dive while the “SERVICE” legend is illuminated.
On the Primary Screen the Surface time will be replaced with the current bottom time,
Blend #1 set point is replaced with the calculated PO2value. Maximum Depth will be
replaced with current Depth, displayed in one-foot increments. Bottom Time will begin
once the GEMINI WU senses that the diver has descended below five feet and continues
until the diver has ascended above three feet. The maximum Bottom Time displayed is 9
hours 59 minutes.

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The Alternate Screen will display the current FO2value that the unit is using in its NDC
calculations, the current CNS and OTU values and the Maximum Depth. (Figure 14 & 14a)
A Depth Alarm, which can be set to warn the diver should a certain depth be exceeded, is
set at 130 feet from the factory. The Depth Alarm issues an audible alarm and the
“WARNING” legend and Depth Digits will flash on and off for five seconds and be repeated
ever two minutes while below the user set depth. The depth alarm is disabled if in the
Decompression Mode since flashing depth digits have another meaning in this Mode.
The maximum depth achieved on the current dive is shown as “MAX DEPTH”. This is
updated once per second.
“REMAIN TIME” (NDC) is the remaining time (in hours and minutes) that the diver can stay
at the current depth without requiring decompression. A “Two Minute Warning” will be
issued when this time reaches two minutes or less. An audible alarm will be issued and the
“WARNING” legend and “REMAIN TIME” digits will flash. By immediately ascending to a
shallower depth, the diver may avoid a required decompression stop.
“REMAIN TIME” (O2) is the remaining time (in hours and minutes) that the diver‟s Gas
supply will last until the User Set Reserve is reached (normally 500 psi). A “Warning” will
be issued when this time reaches zero. An audible alarm will be issued and the
“WARNING” legend and “REMAIN TIME” digits will flash.
Temperature is measured for two purposes. One is to compensate the Depth Transducer
for Temperature variations. The other is to compensate the Nitrogen algorithm for changes
in Temperature that may affect the body. Both of these purposes require that the
Temperature be very slow reacting, just like the Depth Transducer and the body. This
slow-reacting Temperature is what is displayed. For Temperature effects on the body, the
amount of compensation can be set from NORMAL to REDUCED with the Analyst® PC
software Interface, if the diver is using a good dry-suit in cold water. Temperature

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compensation starts at 75 degrees F and gets progressively more conservative as the
temperature decreases. There is no compensation above 75 degrees F.
Bottom Time will begin once the GEMINI senses that the diver has descended below five
feet (see Training Mode) and continues until the diver has ascended above three feet. The
maximum Bottom Time displayed is 9 hours 59 minutes.
ASCENT RATE BAR GRAPH:
The Ascent Rate bar graph and alarms are active in both the Dive Mode and
Decompression Mode. The five-segment bar graph is used to display the diver's rate of
ascent.
Via the Analyst®PC Interface, the Ascent Rate Alarms and Bar Graph can be set to the
users preferences.
The first option is a VARIABLE-BY-DEPTH Ascent Rate. When on, the Ascent Rate Alarm
is determined by depth. As the diver ascends to shallow depths, the Maximum Ascent
Rate is lowered. The Maximum Ascent Rates and their associated depth are:
60 feet or deeper 60 feet per minute
60 to 30 feet feet per minute equal to the depth
Less than 30 feet 30 feet per minute
If VARIABLE-BY-DEPTH is off, the Maximum Ascent Rate Alarm and Bar Graph is
specified by the user and can be from 20 to 60 fpm, in one-foot increments.
Another selection is the bar graph itself. The two selections are either FIXED or
PROPORTIONAL.
With FIXED, each of the five bars indicates an additional 10 feet per minute of Ascent Rate
regardless of the Maximum Ascent Rate selected.
With PROPORTIONAL, each of the five bars indicates 20% (one-fifth) of the selected
Maximum Ascent Rate.
For FIXED, the maximum ascent rate is 60 feet per minute. With this setting, the ASCENT
RATE legend will illuminate but no bars will be illuminated if a diver is ascending at a rate
less than 10 feet per minute.
If the diver has an Ascent Rate that exceeds the selected maximum, the tallest Ascent Rate
Bar Graph will flash, and the audible alarm will sound once per second, and the WARNING
legend will illuminate.
The sensitivity or responsiveness of the Ascent Rate may be selected via the Analyst®,
eight different levels of sensitivity are available.
NOTE: Customizing the Ascent Rate and Ascent Rate Bar Graph are among many of the
additional programmable features available when using the Analyst®PC Interface.
Available features are described in the section “USER CONFIGURABLE OPTIONS”.
As shipped from the factory, the Ascent Rate is set for VARIABLE-BY-DEPTH AND
PROPORTIONAL.
DECOMPRESSION MODE –AIR ONLY/SINGLE GAS NITROX:

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Should a no-decompression limit be overstayed, the GEMINI will enter the Decompression
Mode. In this mode, the Ceiling digits will display the depth at which the diver must stop
and not ascend above during final ascent. The “TEMP” legend and two digits will be
replaced with the “CEIL” legend and two digits. The Ceiling will start at 10 feet and
increase in ten-foot increments as the diver remains at a relatively deep depth. If a Ceiling
of greater than 90 feet is calculated the Ceiling display will flash to indicate that the
displayed Ceiling is divided by 10, i.e. 10 flashing = 100 feet, 11 flashing = 110 feet, etc.
The Remaining No-decompression Time and “NDC” legend will be replaced with
Decompression Time and “DEC” legend (Figure 15). Both STOP time and TOTAL time are
displayed in the upper left hand three digits of the screen in hours and minutes. STOP and
TOTAL time will alternate at the rate of once every two seconds. In this way, the diver can
view the time to spend at a particular STOP depth, and the TOTAL time it will take to
complete all STOPS. Clearly, the larger of the two alternating numbers is the Total
Decompression Time of all stops, and the smaller of the two numbers is the time required
at the current stop. At the ten-foot stop, the TOTAL and STOP times may be the same and
therefore appear to not alternate.
When at a specific stop, the required decompression time at that stop is as shown, and will
appear to count down as it is recomputed every second, based on the divers exact current
depth. The Decompression times (both Stop and Total) are accurate only if the divers‟
depth is exactly the same as the required Ceiling. However, it is not necessary to be
precisely at that specified Ceiling. Appropriate In-gassing or Out-gassing will be computed
regardless of the divers‟ current depth.
A small margin shallower than the Ceiling also exists. Should a Ceiling be „violated‟ (diver
is shallower than Ceiling), the “WARNING” legend will illuminate and flash along with the
Depth and Ceiling digits. An Audible alarm will sound once every two seconds. This
warning will continue until the Depth has been corrected. Out-gassing will continue even
though the diver is shallower than the Ceiling. There is no „Gauge‟ mode or „Lockout‟ on
the GEMINI.
The Total Decompression time forecast at depth is based on the User Configured „Ascent
Rate for Deco Prediction value‟ the factory setting is 60 fpm. If the diver ascends faster or
slower than this value the actual deco forecast times could vary. Regardless of the effects
of the ascent rate, the decompression time forecasted at the deepest stop is accurate.
If the diver surfaces before satisfying his decompression obligation, the GEMINI will
continue to give out-gassing credit as if it were in a dive, but at a depth of zero feet and will
satisfy the decompression time requirements of the required stops using an FO2of 21%.
The unit will continue to log data and perform as if actually in a dive. When the
decompression obligation is finally satisfied, the ten-minute “PostDive Interval” will begin.

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NOTE: COCHRAN does not intend for this instrument to be used for deliberate
Decompression diving.
POST DIVE INTERVAL:
During the first ten minutes (or up to thirty if the unit is in the Training Mode) after a dive,
the GEMINI WU is in the Post Dive Interval. The flashing "SURF" legend and a Surface
Time of less than ten minutes indicate this. Should another dive be commenced before the
completion of the Post Dive Interval, that dive will be considered an extension of the
previous dive. In this case, Bottom Time will NOT include the time spent on the surface in
this Post Dive Interval. However, when reviewing the profile with the Analyst®, the time
spent on the surface in this period will be shown.
CAUTION: To ensure that the dive information is stored accurately in the Logbook, the
WU should be kept in communications with the TU. If the WU is not in communications
with the TU during the Post Dive Interval, when the Post Dive Interval has elapsed it could
store the incorrect dive time in the Logbook.

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CONFINED WATER PROTOCOL (Training Mode): The GEMINI is one of the first dive
computers to offer an operating mode designed to record and store data from training
dives. That is, dives performed in shallow water environments (swimming pools, shallow
lakes, lagoons, etc.) or calm open water environments that have less than 1-foot seas. In
the Training Mode, the GEMINI enters the Dive Mode at a depth of 2 feet instead of 5 feet
and will exit the Dive Mode at 1 foot instead of 3 feet. Also the Post Dive Surface Interval
may be extended, via the Analyst®from10 minutes up to a maximum of 30 minutes in 1-
minute increments after which the dive data is stored in the computer's memory. These
changes permit the Instructor to record the complete training session, including in-water
surface periods, as a single dive. The Training Mode can only be enabled/disabled via
the Professional Edition of the Analyst®PC Interface.
TACLITE™: The GEMINI is equipped with the TACLITE™ tactical low-light fiber-optic
backlighted display. The standard TACLITE™ color is night vision safe red, but it is also
available in yellow for those individuals who have vision difficulties with the color red. The
TACLITE™ can be activated on demand. To turn the TACLITE™ on, tap the face of the
GEMINI and the TACLITE™ will turn on for the preprogrammed number of seconds (1 to
98), then turn off. By tapping the face again the TACLITE™ will turn on again. In this
fashion the TACLITE™ can be kept on for as long as wanted. If 0 is entered, the
TACLITE™ will never turn on. If 99 is entered the TACLITE™ will stay on continuously and
only turn off when the GEMINI does. The number of seconds that the TACLITE™ stays on
can be set via the Programming Mode, factory setting is 10 seconds. The TACLITE™ will
turn off when the GEMINI turns off. If the batteries get too low, the TACLITE™ will turn off
and cannot be turned back on until fresh batteries are installed.
NOTE: The TACLITE™ may not activate when the WU is in the programming mode
or if all three touch contacts are wet and the unit is not in a dive.
CLOCK MODE: The Clock operating mode of the GEMINI TU is NOT enabled when
shipped from the factory. It can be enabled via the Analyst® P.C. Interface or at an
Authorized Cochran Dealer.
TOUCH PROGRAMMING MODE: The Tank Unit and/or Wrist Unit can only be Touch
Contact Programmed when the unit(s) are in the Surface Interval and have zero cylinder
pressure. Touch Contact Programming allows the user to view or program into the:
Tank Unit:
Setting the TU Clock Time
Select the PO2or FO2Operating Mode
The PreDive Prediction Mode
Displaying Mode, mode value, CNS, OTU, TU battery voltage
A Maximum Depth Alarm

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An Added degree of Conservatism from 0 to 50%
Setting oxygen percentage of blend 1 in the Constant FO2Mode
Setting the Normal PO2set point in the Constant PO2Mode
Setting the Blend #2 FO2oxygen percentage
Setting the Deco Blend FO2oxygen percentage
Setting the Deco PO2set point in the Constant PO2Mode
Setting the Deco Bottom Time Benchmark
Setting the Deco Depth Benchmark
Programming TU/WU address code
Wrist Unit
Displaying Mode, mode value, CNS, OTU, WU & TU battery voltages
Programming the On Time for the TACLITE™
Access the Logbook Mode
NOTE: While all GEMINI configurations share certain programming features others are
dependent upon the specific configuration of the unit. Refer to the appropriate manual
section for the relevant programming menu items.
TOUCH PROGRAMMING - TU CLOCK: When the GEMINI is placed into the Clock mode
it will display the time of day in a 24-hour format. The Clock will continue to run when the
GEMINI is in the Dive Computer Mode. The GEMINI can be placed into the Clock Mode
from the Dive Computer Mode when the unit is in the Normal Surface Interval.
NOTE: This Time of Day clock is the same clock that is used to time stamp dives.
Modifying the Time of Day clock will affect the Local Time as viewed via the Analyst®.
TU CLOCK PROGRAMMING PROCEDURE:
TU Contacts 1, 2, & 3 are for programming sequences.
To begin the programming sequence:
1. Turn the Tank Unit and Wrist Unit on;
2. Using a coin or other conductive metal object, briefly bridge Contacts 1 and 2 on the
TU until a short beep is heard and the CLoCk Menu is seen on the display.
3. Using a wetted finger, bridge Contacts 1 & 2 to access the CLoCk Time screen.
4. Shorting Contacts 1 & 2 with a coin will cause the first digit of the minutes to flash.
5. Shorting Contacts 2 & 3 with a coin will increment the numeric value; continue until the
required value is displayed. A confirmation beep will sound with each increment.
6. Next using wetted finger, bridge Contacts 1 & 2 to select the next digit, once selected
the digit will flash to identify that it is being programmed. Bridge Contacts 2 & 3 till the
desired value is displayed.
7. To select Hours short Contacts 1 & 2 with a coin, increment as in step 6 and 7.
8. Repeat step 5 through 7 until all digits have been programmed.
9. To save the changes that have been made bridge Contact 1 & 2 with a coin or other
conductive metal object. Once the next programming option is displayed the changes
have been saved.
The Dive Computer will exit the Clock Mode after 5 minutes and will return to the Dive
Computer Mode‟s Surface Display.
NOTE: Ensure that the GEMINI is in the Surface Mode before commencing a dive.
Figures 50a & 54a show how the Clock display screens appear.

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TOUCH PROGRAMMING MODE:
NOTE: To enable the Programming Mode, the GEMINI must be on the Surface, not in the
Post Dive Interval and cylinder pressure must be zero.
NOTE: All audible and visual alarms are suspended while the GEMINI is in the
Programming Mode. Upon exiting the Programming Mode all alarms are
reactivated.
NOTE: Once a value has been changed and the next menu option selected, the new value
is stored.
NOTE: It is strongly recommended that the Programming Mode is activated again and a
complete review of what was stored is accomplished.
NOTE: If the GEMINI is left in the Programming mode for five minutes without the contacts
being touched, the unit will automatically exit the Programming Mode and return to
the Surface Interval. Once this occurs the GEMINI will retain the modified
programmed settings that have been stored. Options that have not been modified
will retain their previous settings.
TOUCH PROGRAMMING MODE - PROCEDURE:
TU and WU contacts 1, 2, & 3 are for programming sequences.
Regardless if programming the GEMINI Tank Unit or the Wrist Unit the procedure is the
same.
To begin the programming sequence:
1. Analyze the gas blend(s) using a calibrated Oxygen Analyzer (for Nitrox enabled units).
2. Turn the Tank Unit and Wrist Unit on.
3. Using a coin or other conductive metal object, briefly bridge Contacts 1 and 2 until a
short beep is heard and the Programming Menu is seen on the display. The
Programming Menu options depend on whether the unit is activated for Clock, Nitrox,
the number of Gas Blends, and if the unit is in the PO2 or FO2 mode. The Menu
options are displayed in sequence, incrementing to the next selection each time that

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Contacts 1 & 2 are bridged with a coin. The program option is displayed on the upper
row of the display. The current setting for this option is displayed in the lower right of
the display.
4. To reprogram the displayed menu values, bridge Contacts 1 & 2 with wetted fingers.
This will cause the current setting to flash or in the case of multi-digit numbers, the least
significant digit will flash. The clock will toggle between on and off.
5. Using a coin or other conductive metal object, bridge Contacts 2 & 3 to increment the
numeric value. A confirmation beep will sound with each increment.
6. Next using wetted finger, bridge Contacts 1 & 2 to select the next digit, once selected
the digit will flash to identify that it is being programmed. Bridge Contacts 2 & 3 till the
desired value is displayed.
7. Repeat step 5 until all digits have been programmed.
8. To save the changes that have been made bridge Contact 1 & 2 with a coin or other
conductive metal object. Once the next programming option is displayed the changes
have been saved.
All programming sequences use the same routine of using Contacts 1 and 2 to SELECT
the next programming sequence and Contacts 2 and 3 to INCREMENT the specified value.
PROGRAMMING MENU - WRIST UNIT:
The following table lists the various programming choices with their display identification
and figure number, it should be noted that the Wrist Units programming choices are always
the same regardless of how the GEMINI is configured.
Identification Description Figure Page
InF Misc. Information 89 44
TAc dL TACLITE™ On Time. Allowed value 00 to 99. 98 44
LOG Logbook 99 45
TOUCH PROGRAMMING - WU - INFORMATION DISPLAY:

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The InFormation display is accessed via the Programming Mode. The information
presented will depend on the configuration of the dive computer. The information in the
upper right of screen indicates whether unit is in the Constant FO2 or PO2 Mode and the
number of gas blends the unit is enabled for. The following table lists the identification and
the description. Identifier Description
F0 Air only
F1 Single Blend Nitrox, 21 to 50%
F2 Two Blend Nitrox, 21 to 50% and 21 to 99.9%
F3 Three Blend Nitrox, 21 to 50% and two 21 to 99.9%
P1 Single Blend PO2, 0.5 to 1.5 ata
P2 Dual Blend PO2, 0.5 to 1.5 ata and 0.5 to 1.5 ata
The WU Battery voltage is displayed in the lower center of the screen as a two-digit number
with a decimal point. If the unit is configured for Constant FO2 (Nitrox) or Constant PO2,
the screen will display CNS, OTU and battery voltage. The CNS exposure level is displayed
on the lower left as a two-digit number proceeded by a lower case “c”. The OTU value is
displayed on the lower right again as a two-digit number but proceeded by a lower case “o”.
Both the CNS and OTU values are expressed as percentages. Figure 89a displays an Air
Only InFormation screen while Figure 89b displays a typical InFormation screen for a unit
that is enabled for two nitrox blends.
TOUCH PROGRAMMING - WU - LOGBOOK MODE: The Logbook of the GEMINI WU
has two screens, a Primary Screen and an Alternate Screen. Tapping firmly on face of the
unit will switch it to the Alternate Screen. The Logbook is accessed via Touch Contact
Programming (see page 13). This enables the diver to view dive statistics; the GEMINI WU
has the ability to provide diving data for the most recent 12 dives. The most recent dive will
be displayed first. To view the next dive, touch the contacts 1 & 2 with wetted finger after
pausing for a few seconds. Do not use a metal object such as a coin or knife-blade once in
the Logbook since it will cause the unit to exit the Logbook and return to the Surface
Interval.
Information contained in the Logbook will include:
Overall Dive Number Date & Time of the Dive
Minimum NDC Time Fastest Rate of Ascent
Minimum Water Temperature Bottom Time
Surface Interval Before Dive Maximum Depth
Ending Battery Voltage Oxygen % of Blend #1
Maximum DEC Time (Deco Dive) Maximum Ceiling (Deco Dive)
Ending CNS Value (Bar Graph) Ending OTU Value (Bar Graph)
It is not necessary to exit the Logbook Mode prior to initiating a dive.

18
NOTE: While the WU will appear to present more than 12 dives only the dive data for the
most recent 12 is shown. When the apparent 13th dive is shown it is in reality the most
recent dive, the 14th will be the 2nd most recent, etc.
NOTE: The overall Dive Number that is displayed on the Logbook Menu screen (Figure
99a) permits the diver to identify the total number of dives made with that GEMINI WU. If
the logbook example shown is the most recent dive made, it can be readily identified that 9
dives have been made with this specific unit and the 9th dive was made on 18 December
2000 at 11:28 AM.
Figure 07 displays a typical Primary Screen of the Logbook of a Normal Dive.
Figures 08, 8a & 8b display the Alternate Screen for an Air Only, a Nitrox and a PO2
Normal Dive.