JR Xs3 Not for Boat use!! no warranty!!!
I know my Novak XXL's, Futaba's and even Tower's recievers have seen some type of water, mud and dirt, even a totally soaked novak super rooster and they all came out working the next day after cleaning and drying. I guess the circuitry in the JR's just can't handle a short circuit.
The wax idea is a good one. I took apart a Traxxas Reciever apart a few months ago to replace the antenna on it and low and behold it was dipped in wax except for the servo connectors.