Gas-Integrated Dive Computer Transmitters
Let’s admit it. We divers
are a funny lot. Although we are often seen by others as being very adventurous
in what we do, we are usually very unadventurous in the way we do it and that
is especially true when it comes to equipment innovation.
Back in the early ’70s,
divers used tanks with J-valves. When the air in the tank was depleted, the
regulator became harder to breathe from. The diver then pulled the J-valve
release, which allowed access to the last quarter of the tank’s supply, the
regulator freed up and it was time to ascend. It sounds a bit primitive doesn’t
it? Can you believe that when submersible pressure gauges (SPGs) were first
introduced they were met with some resistance?
Some divers saw them as an
additional hazard, an additional failure point. They thought they could easily
explode with so much pressure inside them and a legacy of that is seen today
when trainee divers are still taught to hold the gauge away when they first
turn a tank on. I haven’t ever heard of a pressure gauge so exploding but I’m
sure it must have happened – once!
Air-integrated computers
have been with us for some time. They were resisted as well at first. Myths and
misinformation grew up surrounding them. Because they made a prognosis of
remaining air-time based on a previous breathing rate and the actual depth the
diver is at, many who should have known better declared that they preferred to
know the remaining pressure in their tank, as if that information was not
available as well.
I would say that we all
understand the concept of remaining air-time in minutes balanced against the
total ascent time required (hopefully the former is always greater than the
latter) rather than some pressure reading but it took time for this advance to
become accepted. It was caused by a general distrust in technology. That’s
ironic when we trust technology so much in so many other different ways – as
aeroplane passengers, for example.
Of course there were some
defects in gas-integrating transmitters when they were initially invented,
notably an occasional loss of pairing between transmitter and wrist unit.
Today’s computers pair permanently with their wrist units so the case of
failing to get a tank reading under water with one that needed to be paired
immediately before diving has faded into the past. There was also talk of
photographer’s underwater strobe units interfering with the signal. I’ve never
encountered that and I’ve used a lot of different strobe units as well as a lot
of different computers.
If you have insufficient
confidence in this modern technology, you could always take the redundant route
as you do with other items of diving equipment. Two computers are always a good
idea so why not an extra transmitter? Otherwise, there is usually room on your
regulator to have a mechanical pressure-gauge as well, for use as back-up, if
you prefer it.
You are much less likely to
find yourself run out of gas if you know that your remaining air is going to
last a definite amount of time. I often witness divers looking anxiously at
pressure gauges with needles the wrong side of that ominous red line, worrying
about running out of gas while close to the surface. Worrying simply increases
your hear-rate and with it your breathing rate. The diver that wants to do a
five-minute safety stop with a known ten minutes of air-time remaining is far
more relaxed and gas can last a long time for a relaxed diver in the shallows
so safety stops often get extended. Of course, these computers allow the user
to build in a chosen reserve too.
Computers gas-integrated by
radio link are available from many computer manufacturers including Mares,
Oceanic/Aeris, Scubapro and Suunto.
Happy Diving – John Bantin
