Any sensor to detect the presence of saltwater will not be sufficient for this project. Most dive computers have metal electrodes that are used to detect immersion (either fresh or salt). These electrodes are used to control the device when out of water by moistening your fingers and shorting 2 of the electrodes (they usually have 3-4 of these, one common and then effectively 2-3 buttons). These do not work while in water as the water on the surface of the device shorts all the buttons).
I can just imagine coming up from a 30m+ dive and trying to wipe the unit dry with that magical dry rag that I had in my pocket.
Dive computers use a combination of the immersion sensors and a pressure sensor to detect when a dive starts and ends.
I apologise profusely for taking this entirely off topic (no I don't. I just lied!).
A "new" rule was introduced (circa 1986) that forced expats to obtain diving permits in the coastal port city of Jeddah, Saudi Arabia. We had to get a medical and then go and answer questions asked by a Saudi military officer who couldn't dive himself. So I created this little "protest" which I installed in the rigging of a sunken vessel in 30m of water. That's me "queuing" up for a permit. For all I know, they are probably still queuing there :lol:
(~300 dives in the Red Sea)
Ross McKenzie ValuSoft Melbourne Australia
Being a wiseguy and still managed to keep your head...literally. :wink:
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