View Full Version : How far underwater will a GPS work?

16th September 2005, 10:55 AM
A diver friend has asked me how far underwater a GPS will work and I don't have a clue - anybody know?

Of course we are assuming adequate waterproffing.

16th September 2005, 03:11 PM
gps are not designed to work under water, the posiblility of picking up a satilate would be minimal as well. this I only presume as im not about to test mine under water :D


16th September 2005, 04:06 PM
Apparently they can pick up satellites when near the surface - I was wondering how far down this lasted. People happily take cameras worth $$$$$$$ underwater, so a GPS in a similar case should be OK. The use in question was not very far down in murky lake water.

The Explorer
16th September 2005, 05:04 PM
Good question - I would like to know the answer also ....be handy for those crayfishing expeditions to save going over old ground or sneeking up on known holes. Got a feeling they dont work any significant depth though - as someone would have built a fully waterproof one if they worked underwater.sure they would sell well..Never seen anywhere saying they dont work so I live in hope.(even if limited hope)

16th September 2005, 08:12 PM
To the best of my knowledge a few mm of solid water is enough to attenuate the satellite signal.

Most underwater (dive) systems seem to work by having the GPS on the surface tethered to the diver working underneath.


3rd October 2005, 12:58 PM
Do they actually make GPS units which are waterproof? I know the ones I've looked at are good if you accidently drop it in the drink and retrieve it almost immediately, but don't know if fully 'proofed' ones are commonly available.
The signal coming from the sat would have limited penetration through water, considering comms with subs is usually in the very low frequency range and sats operate in either extra high or super high frequency range.