Ooops :)

[tsubaki]

I'd bet the problem is with the light switch. With the power on, turn the lights on and off quickly several times and see if at least one of them come on, it's possible corrosion has infiltrated the switch.
I have no idea (without being there) where the fuse panel might be located. Most new boats that size, might have them integrated with the helms console (power) panel.
Again, I'd have to be there to trace it down, sorry.