Get a gallon jug of CRC 6-56 and a good squirt bottle. I spray this stuff on everything under the engine cover, including the terminal blocks. Then I hit everything on the boat that I think might ever rust or corrode, and into every jack, plug, and moving part. Do this after washing every time. It seems messy at first, but it magically absorbs after a few days, and things will stay looking new for years, even in the saltwater.