What outboard do you have? With my pontoon there is a wiring harness coming from the motor for the gauges. And a inline 50 amp fuse from the battery for power for the lights and gauges. The wiring is color coded by the motor brand as someone posted above.
First I've heard of it but I don't own a trailer and the first time I've loaded it was on the guys trailer that is working on my boat and I only did what he told me to do.
The boat shown making the record 115 MPH run is:
Rowland boat, named Tooned In, is a 25-foot 2010 South Bay tritoon powered with triple Mercury Promax 300X outboards.