I know it seems like a simple system but some how the Nav lights are tied into the courtesy lights. Not sure if someone did a shade tree repair or if it is supposed to be like that. I got the boat at an auction so I cant ask the last owner.
There isn't a wiring diagram for a boat internal wiring, You either have something miss wired or something is shorting to another connection. Just need to follow the wiring.
This is a basic arrangement and in most cases this is how it should be done but not necessarily how it was done
