Sealing "waterproof" handheld electronics

[4runner]

Other than a clear plastic waterproof drybag or case, does anyone know of any waterproofing products that can be applied to the rubber gasketed little doors on a handheld "waterproof" VHF, camera or GPS to keep the water from getting past the battery doors. It seems like a fairly common problem with many manufactures and products. I've tried 303 on the rubber gasketing on a Garmin GPS12xl (old unit no longer supported) with no luck. Another suggestion was vaseline, but I would think that could melt in the sun and possibly harm the batteries or whatever is being protected by the little doors.

Thanks

[Bill NH]

A THIN coating of petroleum jelly is often recommended for O-ring seals.  Wipe it on, then wipe off the excess.  Its not meant to make the seal, just to keep the O-ring pliable so that it can function correctly (of course if the doors don't fit correctly to start then this won't help...).   If you don't apply to excess I wouldn't worry about it damaging inside components.

[AdriftAtSea]

I wouldn't use vaseline on o-rings, as some are made of rubber and the vaseline will attack the o-ring material.  You're much better off using silicone grease on the o-rings instead, as it won't attack the material regardless of what it is made of.

As for sealing small electronics... you could try a layer of rubber cement over the openings...you can generally peel rubber cement off of most surfaces but it would form a waterproof film.

[Karletto]

silicone sealant

[AdriftAtSea]

Now you've gone and done it... you said the two words that should never be mentioned in conjunction with a boat.  You should NEVER use silicone on a boat or its associated gear...

[4runner]

After some research on other forums I've concluded that the best way to keep the water seepage out of electronics is to:

Rinse the unit in fresh water and let it dry after every use, especially saltwater use and before opening the little doors.

Open any of doors and dust off any dirt, salt or sand from the rubber seals with a small artists paint brush.

Coat any of the rubber gaskets or O-rings with a thin coating of Sea and Sea Silicone Grease. Available from dive shops or camera stores. Some camera manufacturers have their own brand specific product, but I'm told S&SSG works for all of them. 

Also check to be sure the tiny spring loaded latches on the doors are working so you don't close the door to find out later that it wasn't latched and water got in.