I don't do anything to my radio gear, at least in that sense.
What many of us do is spray Corrosion X onto the circuit board of your receiver. This protects the receiver from shorting out due to water getting into it.
Option 2 would be to enclose your radio gear in a water-resistant box. This is how my boat is set up
Option 3, and probably the best option, is to seal the boat with water resistant tape at the joints where the top of the boat and the deck come together