My only experience rewiring a sailboat was many years ago. The
boat was lying in Bellingham, WA and the absentee owner was the son of a very well known actor in Hollywood CA so he could well afford to hire a
marine electrician but wanted to do the
work himself so he knew how to troubleshoot the systems.
The boat was nearly new and he was the original owner who had purchased her new in the Far East. She was a 1988 Hans Christian, either 38 or 43 feet.
When we pulled the
electrical panel off to get started, all the wiring was black with no hint which was positive or negative or ground! There were a number of boats from that yard in
Taiwan that came out in this condition we heard later. We ended up rewiring. with black as negative, red as positive and green as ground for the few circuits that needed a ground.
I mention this because it turned out to be a hugh task, much of which I did myself as my buddy/owner had to return to SoCal not long after we got started.
I wasn’t working so could devote full time to the job but unless you have unlimited time, hire someone to help you.
Phil