Re: wiring diagram
I build pontoons now and really doubt I could get a wiring diagram for any of our boats.
The place that makes the harnesses comes in and lays everything out then they go make them and we get boxxes of wire harneses with the model number on them so no diagram is ever needed.
Cars have manuals and wire diagrams because they build 200,000-500,000 of a specific model and can spread the cost over many units where they may have made 100 or less of your boat.