Boat complete but forgot where fuse is?? Or breaker any help??

Fuse or breaker behind sink may be fuse ?Or from what I was told breaker next to shut off under rear seat ??

Not really a centralized fuse or breaker panel on my 1990 27/29 other than the 3 "spare" fuses under the helm. My head unit is powered from the Interior power switch on the side switch panel
I'd start looking there or under the helm for an inline fuse holder.

Thanks GPS & Power hatch lift were breakers under rear seat hope it is inline fuse ? Also stereo also not getting power hoping it's the same fuse?

All good had guy run new lines for both stereo & water