That is an excellent question and is asked more often than you think.
Electric brakes like what come in the Electric Trailer Brake Kit # AKEBRK-2 can be submerged in water when you are loading/unloading your boat. Since water and electricity don't play nice together you do need to disconnect the wiring to your tow vehicle before backing into the water.
When you make all your wiring connections I recommend using head shrink butt connectors like part # DW05745-10 or part # DW05744-10 to... view full answer...