Computers
Scuba computers, or dive computers,
are compact digital devices which
perform the task of nitrogen management
without the need for a watch or dive
tables. Combining a timer with a
depth gauge, and intelligent software
which computes absorption of gases,
dive computers are popular with experienced
recreational divers. While it is
essential that all divers learn about
residual nitrogen and decompression
using dive tables, a computer is
a valuable device that enhances your
dive experience by automating nitrogen
management.
A dive computer does not plan a
dive for the scuba diver. A scuba
diver is still responsible for planning
a dive safely in accordance with
health guidelines. What the computer
does is: keep track of depth and
time spent underwater, computes the
amount of nitrogen present in the
diver's body, alerts the diver of
levels getting too high and guides
the diver to make appropriate decompression
stops, if necessary.
On a traditional dive table there
are only 2 variables used to describe
a dive: maximum depth and time. The
calculation of absorbed nitrogen
assumes that the diver plunged immediately
to maximum depth, stayed there for
a duration and then bobbed back up
to the surface. Then the dive profile
is "square" - if it is
graphed on an X-Y grid it would look
like a rectangular trench. In practice
a dive is never like that: a diver
will descend slowly, swim around
and up and down, change depth to
navigate reefs or bottom formations
and then slowly ascend to the surface.
The most enticing advantage of a
dive computer is longer bottom times.
Dive tables with a square profile
are necessarily conservative; the
exaggerated absorption on the safe
side. The accurate curved profile
of computerized depth tracking invariably
allows the diver to stay down deeper,
longer.
Here are some things to consider
when choosing a dive computer:
- Research the dive computer's brand
and model. Look for recognizable
manufacturers and consult consumer
guides.
- Is it easy to change the battery
without dissembling the unit?
- Is the dive computer's interface
intuitive, easy to read and backlit?
- Some dive computers can upload
your dive data to a PC for use
in scuba
planning and logging software.
Not all dive computers have this
feature.
Do you want this feature?
- Will the dive computer handle gas
mixes other than air, such as nitrox?
- Does the dive computer support
decompression management and a "time-to-fly" feature?
- Does the dive computer use a
well-tested algorithm for calculating
gas absorption
and decompression?
- Are the buttons large, spaced
far apart and easy to press
while wearing
neoprene gloves?
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