Page 110 - AlertDiver_Winter2013

Dive computers have evolved rapidly since the
first modern, diver-carried electronic dive
computer (ORCA Industries’ EDGE) became
commercially available in 1983. The emergence
of dive computers prompted questions about their safety,
evaluation procedures and guidelines for use. Because little
data existed on repetitive diving, there were concerns about
computers’ ability to manage multiple deep dives.
Today, dive computers’ ability to monitor decompression
status and ascent rate in real time is well established. And
computers allow increased flexibility: They permit dives of
unlimited complexity while providing guidelines for limiting
decompression stress. Because of this improved flexibility,
dive-computer guidance is generally expected to present a
greater risk of decompression sickness (DCS) than the use of
a dive table based on the same decompression algorithm.
The computer’s calculations use the actual depth of the
dive rather than being rounded to the next deeper depth, and
repetitive dives are based on the entirety of the underlying
decompression model (i.e., all tissue compartments are
considered). Most dive tables use only one of the decompression
model’s tissue compartments to calculate repetitive dive
allowances, which adds a margin of safety. With dive computers,
there is also the potential for electrical or mechanical failure and
user error. However, based on reviews of the available databases
of dive injuries, dive computers appear to have acceptable safety
records regardless of the algorithm they use.
Validation
Dive-computer validation consists of several steps, which
include: 1) verification of a clear and unambiguous
information interface, consideration of ergonomics
and rigorous leak testing; 2) a procedure for testing the
decompression model and algorithms (as in decompression-
table testing); 3) confirmation of the computer’s function in
simulations; and 4) field testing.
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B y M i c h a e l A . L a n g , D . P h i l .
Validation of Dive Computers
An ORCA Industries EDGE among a variety of modern-day dive computers
STEPHEN FRINK / DIVE COMPUTERS COURTESY DIVERS DIRECTAND QUIESCENCE, KEY LARGO, FLA.