Working around electronics and saltwater, I have an arsenal of things I use for keeping saltspray and saltwater off of things that conduct electricity. These are my favorite weapons against water intrusion.
Silicone grease..available at diveshops, Grainger and Radio Shack. Works around things that are made of rubber since petroleum adversly affects rubber seals etc. Stuffing underwater electrical connectors with this displaces any water that might get in there if there is a leak.
Tef-Gel..this stuff never hardens, never washes off and its slicker than snot and sticks to anything. I use it on terminal blocks, crimp connectors etc...it totally stops corrosion.
http://www.tefgel.com.au/
Heat shrink connectors....Completely keeps water out of crimp connectors such as butt joints and ring terminals.
http://www.westmarine.com/webapp/wcs...0001/125/124/9
Liquid electrical tape. Coat anything and it dries in an hour or so forming a completely water tight seal.
http://www.westmarine.com/webapp/wcs...allpartial/0/0
Self-fusing tape....goes on like regular tape and then self-fuses to itself....this stuff is magic. No seams for water to leak through and it remains pliable. I use it for creating a water tight seal such as where I have to run wire through a deck or cabin top.
http://products3.3m.com/catalog/us/e...er/output_html
Boeshield...Developed by Boeing for use on aircraft. Its a waxy substance that I have sprayed on printed circuit boards. Conpletely keeps water off the board and stops any shorts or water damage. Does not conduct electricity. If I were to go to phase cooling for a CPU, I would spray this stuff all over the board to stop shorting caused by condensation.
http://www.theruststore.com/Boeshiel...osol-P3C4.aspx
Polysulfide bedding compound..... Dries slowly but once it dries it sticks like crazy, even to epoxy and glass. Remains rubbery and holds up to UV. Better hope you never have to remove this stuff. Made by Sikaflex. Way better than silicone sealant.