DIVE COMPUTERS Insert Shop Name Here

How a Computer Works Liquid Crystal Display Step 3. The microprocessor takes depth, pressure and time data and performs calculations and outputs the information to the LCD. Liquid Crystal (LCD) Step 4. Process repeats every second. Clock Step 2. A/D converter changes voltage into numbers that the microprocessor can use. Elapsed time is also sent. Micro processor LP Transducer (Depth) Temp Sensor HP (Tank Pressure) Step 1. Sensors send voltage information to the Analog to Digital (A/D) converter. A/D Converter

Tables vs. Computers Tables based on square profiles. Allowable dive time based on maximum depth, no matter how long you stay there (1 minute or 20 minutes).

Tables vs. Computers

Basic Theory Tissue Compartments - Mathematical models used in the computer algorithm Nitrogen Tolerance - How much nitrogen pressure a tissue can absorb Half Times - The amount of time it takes the tissue to fill by one half.

Tissue Compartments

Fast Tissue @ 5 minutes

Fast Tissue @ 10 minutes

Fast Tissue @ 15 minutes

After 6 half times The tissue compartment is considered full The computer will prescribe required decompression stops

Tissue Loading in Action Using Suunto Dive Manager (click on screen to start/stop; click off screen to go to next slide)

Types of Computers Standard Wristop Air Integrated Hoseless

Standard Computers Basic Features Current Depth No decompression time Max depth Bottom Time Ascent Rate Logbook memory Pre-dive planning Nitrox Suunto Gekko

Standard Computers Advanced features Electronic backlight Dive simulator Plan Simulator PC Download Bookmarking Suunto Vyper

Wristop Computers Basic & Advanced features < Stinger Basic & Advanced features Multi-purpose – not just for diving Always with you Freediving features Mosquito >

Air-Integrated Computers Same features as basic computer More accurate pressure than analog gauges Calculates air-time remaining

Hoseless Computers Includes same features as air-integrated computers Transmitter sends pressure info via radio wave Specially coded to prevent interference from other hoseless computers

Demonstrated with the Suunto USING A DIVE COMPUTER Demonstrated with the Suunto

Button Interface Mode (Menu) Activate Smart button Use bezel labels when no LCD prompts

Button Interface Smart button Select: Enter the mode LCD prompts override bezel prompts Select: Enter the mode Quit: Exit a mode or menu OK: Accept the setting

Button Interface Plan Button Puts computer in Dive Planning Mode Time Button Switches bottom display to show time of day

Button Interface Up Button Scrolls up or increases value Down Button Scrolls down or decreases value

Click on video clip to start & stop Manual Activation Press On (Mode) Button All segments displayed Battery Check Click on video clip to start & stop

Battery Check 4 segments: Normal, full battery

Battery Check 3 segments: Normal, battery is getting low or temperature is low. Battery replacement is recommended for cold conditions or dive trip

Battery Check 2 segments: Power is low and replacement recommended. LOWBAT warning and icon displayed.

Battery Check 1 segment: Change the battery. Activation and functions disabled.

Automatic (Water) Activation Electrical connection between interface contacts and buttons Starts automatically when submerged

Automatic (Water) Activation AC = Active Contacts Displays Time and Date Goes to dive mode when deeper than 5 feet

Click on video clip to start & stop Time Display Press TIME button Toggles dive time & pressure with Time of day and temperature Click on video clip to start & stop

EXERCISE #1 Manually activate computer Change time display

Dive Planning Allows you to scroll through depths in 10-foot increments and see the maximum dive times for each depth. The dive plan constantly updates as you extend your surface interval between repetitive dives.

Dive Planning Press Plan Button Mode indicated by “PLAN” Use bottom buttons to scroll Press smart button to quit Click on video clip to start & stop

EXERCISE #2 Plan a dive to 100 feet What is the no-decompression limit? ANSWER: 17 minutes

Click on video clip to start & stop Memory Modes LOGBOOK 50 hour memory Four pages for each dive Profile read out HISTORY Max depth ever reached Total dive time hours Total dives PC SET Reset feature (shop only) Click on video clip to start & stop

EXERCISE #3 Go to MEMORY > HISTORY On your computer, what is the total dive hours? Number of dives? Maximum depth?

Set Modes SET MODEL SET ALARMS SET TIME SET ADJSTMENTS Air/Nitrox. Dive time alarm Depth alarm SET TIME Time, Date, Alarm Clock SET ADJSTMENTS Altitude adjustment Personal adjustment Metric/Imperial Click on video clip to start & stop

QUICK QUIZ #1 What are the two main menu modes? ANSWER: SET and MEMORY

Dive Mode Display Current Depth Maximum Depth No Decompression Time Dive Time Temperature Consumed Bottom Time

Dive Mode Display Notice how going deeper decreases the allowable no decompression time.

Dive Mode Display Notice how going deeper decreases the allowable no decompression time.

Dive Mode Display Consumed Bottom Time (CBT) As no-decompression time decreases, more segments on the CBT appear. The graph is color coded green, yellow & red, giving you a quick visual reference of your no-decompression time.

Dive Mode Display Consumed Bottom Time (CBT) RED ZONE: 0 minutes; deco stops required 5 YELLOW ZONE: 10 – 5 minutes 10 20 30 40 50 60 80 100 GREEN ZONE: 200 - 20 minutes 200

Dive Mode Display

Dive Mode Display Maximum Depth Locks In Notice how the maximum depth reading stays at 100 after ascending to a shallower depth

Dive Mode Display Ascent Rate Bar Graph The diver just ascended from 100 feet to 60 feet in less than a minute. This causes the ascent rate bar graph to fill up…

Dive Mode Display Ascent Rate Bar Graph >39 ft/min. 33-39 ft/min.

EXERCISE #4 Using dry-erase Gekko display, fill in the display using the following dive information: Depth = 100 ft Max depth = 120 ft No-decompression time = 5 minutes Dive time = 12 minutes Ascent rate = 2 segments Temperature = 65°F CBT = 10 segments

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Multilevel Diving in Action No Dec Time counts down as you remain at the same depth No Dec Time increases as you ascend to a shallower depth

Dive Mode Display Recommended Safety Stop Ascending above 20 feet triggers the safety stop feature. The word “STOP” appears and safety stop timer counts down from 3 minutes to 0 minutes.

Dive Mode Display Recommended Safety Stop Ascending above 20 feet triggers the safety stop feature. The word “STOP” appears and safety stop timer counts down from 3 minutes to 0 minutes.

Dive Mode Display Recommended Safety Stop Ascending above 20 feet triggers the safety stop feature. The word “STOP” appears and safety stop timer counts down from 3 minutes to 0 minutes.

Dive Mode Display Recommended Safety Stop When two dashes appear (- -), it is OK to surface.

Dive Mode Display

Surface Mode Display – Screen 1 No Fly Icon When the No Fly icon appears, you should avoid flying in a commercial aircraft until the icon disappears.

Surface Mode Display – Screen 1 Diver Attention Symbol When the Diver Attention Symbol appears, you should extend your surface interval before doing the next dive.

Surface Mode Display – Screen 1

Surface Mode Display – Screen 2 Surface Time Surface time is the amount of time you have been out of the water after making a dive

Surface Mode Display – Screen 2

Surface Mode Display – Screen 3 No Fly Time No fly time is the amount of time you have to wait before flying on a commercial airliner.

Safety Guidelines for Computer Assisted Diving

Read the Manual Before Diving Each dive computer has its own special parameters of operation and usage limitations. The importance of proper training in the operation of the dive computer cannot be overemphasized.

Each Diver Should Always Have Their Own Dive Computer Sharing computers is dangerous!

Dive Conservatively with Respect To the No-Decompression Limits

Perform Only No-Deco Dives Situations requiring direct ascent to the surface while in decompression mode are a potential problem causing decompression sickness. These situations might include: Insufficient air supply to make any required decompression stops. Emergencies such as running out of air, rupturing an air hose or having a buddy run out of air.

Do Not Exceed the Computer Specified Ascent Rate All Ascents Should Be Slow! Always monitor the dive computer during ascent.

Make A Safety Decompression Stop On Every Dive Safety stops are beneficial in the prevention of decompression sickness. A safety stop should be made on every dive at approximately 5m/15ft for three to five minutes

Avoid Reverse Profiles Multi-level dives should be initiated with the deepest segment of the dive first and subsequent portions of the dive made in progressively shallower depths.

Avoid Repetitive Deep Dives Repetitive dives to depths in excess of 30m/100ft should be avoided.

Do Not Reset Computer Until Out-Gassing Is Complete A dive computer should never be reset or turned off between dives or before it has calculated out gassing. (Most computers today will not allow you to turn them off until they have completed off gassing.)

Dive Computer Failure Procedures There are two possible failure situations: The dive computer could fail during a dive, or it might fail during a surface interval.

Procedure For Computer Failure During A Dive Ascend immediately; do not to exceed computers ascent rate. Make a safety stop at 5m/15ft for three to five minutes to add a safety margin. If computer fails while in a decompression mode, proper decompression stops cannot be monitored. Another reason to avoid decompression diving.

Procedure For Computer Failure Between Dives Three options for handling a computer failure during a surface interval: Make a single repetitive dive using the adjusted no-decompression limit given by the computer during its surface scrolling mode (Plan Mode). Repetitive dives could be made to depths less than 6m/20ft. End the day’s diving activities.

Procedure For Computer Failure Between Dives It is recommended that there should be no diving within 24 hours prior to using a new computer or a computer that has been turned off since a previous full day of diving may have left the body with a significant amount of residual nitrogen.

Drinking Alcohol and Computer Diving Do Not Mix Increased susceptibility to decompression sickness due to dehydration and changes in blood characteristics.

Flying After Diving Procedures Many dive computers feature flying after diving indicators which tell a diver when it is safe to fly. Most allow a diver to fly within a short period of time following a day’s diving activities. Many authorities recommend that recreational divers wait 24 hours after diving before flying to add a safety margin.

Summary of Dive Computer Guidelines Read the Operation Manual Thoroughly. Each Diver Should Have Their Own Dive Computer. Dive Conservatively With Respect To The No-Decompression Limits. Perform Only No-Decompression Diving. Do Not Exceed The Computer Specified Ascent Rate. Make A Safety Stop at Approximately 5m/15ft For 3-5 Minutes During Ascent.

Summary of Dive Computer Guidelines Make The Deepest Dive First. Repetitive Dives In Excess Of 30m/100ft Should Be Avoided. Do Not Turn The Computer Off Before Out Gassing Is Complete. Know The Computer Failure Procedures. Know The Flying After Diving Procedure.

A Final Note: Dive Wisely Dive computers have given divers the freedom of multi-level diving. This freedom allows us to spend more time exploring and enjoying the underwater world. Remember that neither the dive tables nor a dive computer can absolutely insure that a diver will not get decompression sickness. These devices are based upon mathematical models that have been supported by experimentation and research. Use them properly, following the manufacturer’s directions and the dive guidelines previously recommended. Using these devices properly and conservatively will greatly prevent the likelihood of injury from decompression sickness.

Advanced Topics Nitrox Decompression Diving

Nitrox Standard air roughly 21% O2 & 79% N2 Enriched Air Nitrox (EAN) has higher O2 and lower N2, e.g. 32%-68% Lower N2 allows for longer bottom time, but… Higher O2 limits how deep you can dive The Gekko can be programmed for O2 up to 50%

Set Gekko to Nitrox Mode (SET > MODEL > NITROX) O2% can be set to 21-50% PO2 can be set to 1.2 to 1.6 MOD is calculated automatically Click on video clip to start & stop

EXERCISE #5 Set to Nitrox Mode Set O2% to 36 Set PO2 to 1.5 What is the MOD? ANSWER: 100 feet Go to Plan Mode What is the No Dec Time @ 100 feet? ANSWER: 31 Minutes

Nitrox Dive Display O2% Display When in Nitrox Mode, the O2 setting is always displayed.

Nitrox Dive Display Oxygen Limit Factor (OLF) >100% 100% Displays CNS or OTU, whichever is greater Bottom segment flashes when controlled by OTU 10%

Nitrox Dive Display

Nitrox Dive Display: Alternate Press Time Button for alternate display Shows CBT and time of day Stays on for 5 seconds

Nitrox Notes 21% is the default O2 setting If set to 22% or higher and a dive IS NOT made within two hours, defaults back to 21% If a dive is made @ 22% or higher, Gekko retains setting until “clean” Once a Nitrox dive is made, cannot switch back to Air Mode; must use 21% instead

Decompression Dive Mode Occurs when No Dec Time becomes 0 Cannot ascend directly to surface Must stop at “Ceiling” to decompress

Decompression Terms Ceiling: The shallowest depth to which you can ascend Ceiling Zone: From the ceiling to 6 ft below. Optimum decompression depth Floor: Deepest depth at which deco time obligation does not increase Decompression Range: Depth range between ceiling and floor. Decompression is slower near floor

Decompression Dive Mode CBT completely full Ceiling Depth replaces max depth Up Arrow = Below the Floor. Start ascending immediately Ascent Time replaces no-deco time. Ascent time = time to ascend from depth + time to decompress

Decompression Dive Mode Above the floor The up arrow disappears. No longer adding to Ascent time Still too deep for optimum decompression

Decompression Dive Mode At the Ceiling Zone Up and Down arrows are displayed. Optimum decompression depth

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