oohh ooohh ooohh pick me! pick me! I've done that!
It's not that hard (time consuming and you get to be covered in fiberglass dust) or even terribly structural I think. especially when you figure you are bolting the giant outboard bracket over it. I'm sure it could be done with less effort, I bet Ryan has a easier method, but I just made a 2 x 3/4" plywood plug and epoxied it in place.
Grind all inside edges back to clean fiberglass or down to the foam and grind around the edges of the hole in a 12:1 ratio of the thickness of the fiberglass skin. I think it was 1/4 so you grind 3" all round it. Epoxy the plug in place with thickened epoxy (wood flour works nicely) and then overlapping layers of fiberglass until it's level. That according to the fiberglass guys I got my lessons from will create a patch as strong as it was before.
You can see me in all my naivete,
Bateau2 - Builder Forums • View topic - 24' Zodiac Project
That is a great fiberglass site. They are good with advise and (shocker) they sell everything you need. The epoxy the sell is good stuff. Less expensive and easy to work with. The 2:1 ratio is good for when I was learning.
