Well well, as an engineer I can't keep my fingers out of this one.
I guess Sparky is worrying if his computer tells him the right things.
As for starters, water(liquid) don't compress, so the idea of having a container with water and compressing it with air doesn't work. If water would compress, it woud get thicker whlie going deeper and there wouldn't be a sport called diving I guess, which would be a major bummer.
So, what do we know about gas and it's behaviour from the OWD course? Right, as pressure(depth) increases, the gas(air) compresses, remember that empty plastic coke bottle trick? Now, what is a dive computer anyway? A device with a pressure sensor, cpu, display, battery and a bunch of software that does calculations according to time and the pressure(depth) data from the sensor.
Now, the key to bust this myth is (hehee, now I'm sounding like Adam and Jamie from the Mythbusters
) how to get the computer pressurized to a certain pressure that equals certain depth?
Well, actually it's quite easy. How we are treating DCI/DCS? In the recompression chamber ofcourse, so easiest way would be to take the computer to a local hospital that has this equipment, hop in with the computer, take a ride and see what it gives you.
While, that might be a little over for your budget so how to make a small one by yourself? Well I don't know much about mechanical engineering but I'd assume that maybe you could take an old scuba tank, cut it in half and mount a very thick glass window to it, put in the comp, add some air slowly and see what happens.
Back here the dive computer manufacturer
Suunto test drives all the new computers down to 100m (300 something ft) and the old ones that are sent in for repairs and battery change. I have to say that I like them a lot, their service is something extraordinary. They fix and sometimes even change old computers to new ones that are sent in for maintenance, even after the warranty period has gone. Ofcourse there must be a real defect in the comp. but they do that and that is what I call service!
So something around these lines I guess but if you ever make that testing tank and bust your comp. please don't blame it on me.
So stop worrying and get diving!
.Janne
Ps. If you still have doubts, then buy a second one for backup, that is what I do, since water and electronics don't mix.
not to mention is water even compressible??
