February 02, 2005
How safe are scuba dive computers?

I came across this interesting-looking abstract where someone has done a piece of research I wouldn't have minded testing myself as a practical science project:

Huggins KE, Catalina Hyperbaric Chamber, Wrigley Marine Science Center, University of Southern California, Santa Catalina Island, California.

BACKGROUND: Most dive computer comparisons address responses to fixed decompression table schedules or fabricated dive profiles. This study tests the potential for evaluating dive computer algorithms by exposing them to profiles that have known human subject results.

MATERIALS AND METHODS: Fifteen dive computers were exposed to profiles with either "high," "moderate," or "low" risk ratings, based on occurrence of decompression sickness and Doppler score outcomes from human subject dives. Profiles fell within, and slightly outside, the standard operational range of recreational divers. The profiles included a multi-day, multi-level repetitive dive series of "low risk" profiles (<130 fsw [500 kPa]), two "moderate risk" multi-level single dives (130 fsw & 60 fsw [286 kPa] maximum depths), a "moderate risk" short 165 fsw (609 kPa) decompression dive, and a "high risk" long 36 msw (466 kPa) decompression dive. Remaining no-decompression time (NDT), or required total decompression time (TDT), was recorded from each computer prior to departure from each depth in the profile.

RESULTS: The results from the multi-day multi-level "low risk" profiles ranged from three computers requiring decompression following the first dive of the first day to five computers completing all nine dives within their no-decompression limits. The "moderate risk" single multi-level dive results ranged from 20 minutes NDT to 19 minutes TDT at the end of one of the dives. None of the computers permitted the "high risk" decompression profile. However, all cleared before the end of the first 30-fsw decompression stop of the "moderate risk" 165-fsw decompression profile.

CONCLUSIONS: Response to the 165-fsw dive indicates that more conservative dive computer algorithms would be appropriate for short deep decompression dives. Since dive computer manufacturers do not validate their algorithms with human subject tests, running the algorithms against a battery of previously tested dive profiles allows some rudimentary level of validation.

Source: Abstract# X304, UHMS ASM 2004, Session X HTNA conference 27 MAY 2004

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personally.......I want human test subjects

Posted by: Dark fantasy art on February 4, 2005 02:11 AM

My computer at home hardly ever crashes. This brings me to my next point: Computers Crash! But if you are a responsible somewhat experienced diver you should have a 'feel' of your dive and anything out of the ordinary with your dive should send you to the top. SLOWLY!

Basically you usually get what you pay for. In diving your life is what you pay for because of faulty equipment.

Be safe and Keep your Lines Tight

Posted by: Weekend Scuba Diver on September 8, 2005 01:55 AM

Interesting, thanks for putting the entry up.

Working as a divemaster, I live by my computer, but as Weekend Scuba Diver says, I have a feel for my dives.

I have often wondered what my Doppler score would be, especially after completing a couple of dives at 35 to 40 meters in one day.

Posted by: Richard on September 18, 2005 11:55 AM
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