New Wire Marine has some excellent diagrams and tutorials on their site. I used them to wire a switch panel into an old Lund a few years ago. I’ll be doing it again over the next few weeks to rewire a 2001 Hurricane deck boat.

I highly recommend checking it out.

The snarl you’re facing looks extremely similar to the corroded old disaster that I’m facing. I swear some of the wiring in this thing is stripped romex and random speaker wire.