After a rain my boat blows a 20 amp fuse attached to the main battery and I lose my gauges and fish finder. If I replace the fuse everything is ok for the rest of the day. One time I replaced the fuse on the lake and everything was fine until I trailed to another lake. After I put the boat in the water the fuse was blown again. The boat is aluminum and I'm thinking that maybe the problem is the one of the pumps for the bilge or live well. Maybe the water moves to the bilge and shorts out. What puzzles me is that I don't turn anything on or off when this fuse blows. Any ideas? The only thing I do is raise the motor up and down.