I have a garmin 172C. Moisture forms on the inside of the screen after being stored for a while. When the boat is uncovered the moisture will go away after a while.

Yesterday it kept shutting itself off after a few minutes. After being on the water for a few hours the problem stopped.

How can I keep this moisture from forming in the unit? I was thinking of putting some silicone around the case where the seam is.

Mine kept cutting off and it turned out to be the power wire that comes across from the driver's side. Apparently it got pinched between the deck and hull and eventually broke. B ut I never have any moisture in it.

im my experience with these type of instruments, what you describe happens when they get wet inside at some point. then they can never ever dry out. what happens is that it creates its own little weather system inside the sealed case and the moisture condenses on the screen until it warms up and then changes state. my solution has been to disassemble it, dry it very very thorougly with a blow drier and hit all the boards with spray contact cleaner, and put it all back together and 999 times out of a 1000 that fixes it. if you seal it w/ silicone now youll just trap all that moisture in there and the borads will eventually corrode and the device will die.