Replacing my Furuno Navpilot with Garmin Reactor. Since the control unit is smaller, I’m looking for the best way to repair the holes. Thought about seeing if any of the local shops/gelcoat guys had a cutout I could pop in there and then re-gell.
It's not that simple to just "pop something in there and re-gel". There's much more to it. To do it right, the plywood that you fit in there has to be properly glassed in. This requires sanding the existing area down/back at least a coupe inches (ideally, it would be more, but this isn't a major structural area) so the layers of glass that are layed in will allow the final layer of gelcoat to be flush with the entire area. You also need to put a layer of glass on the back side, too. Anything short of this and the final gelcoat will look like crap and likely crack.
However, you could just put a cover pate of starboard (whatever color you want) over the entire area - about an inch larger than the hole. Then install the new electronics into the starbaord. That would be PLENTY strong enough as is with no need for any filler.