Forward fish box drain (Update)

[FLexpat]

Get some 1" dowel rod. You will need a couple of pieces about 6" long and one just the thickness of your hull - attach that piece to the center of a small piece of plywood. Cover it in saran wrap and plug the hole from the outside - brace it in place. Mix up some cabosil with some glass fiber in it - you will need a couple of batches big enough to fill the void. Cover the other dowel pieces with saran wrap - you will use these as 'plungers' like in a syringe. Fill the hole with cabosil and work as much as possible into the void. Refill the hole with cabosil then push the plunger in to force the cabosil into the void. Leave it in to set then the resin will release from the saran to let you pull it out. You may have to bore it out and repeat it to get a good fill.

[FLexpat]

Forgot to say to smooth up the edges of the hole first - you don't want to tear or cut the saran wrap. A 1" polyethylene rod is better but not in most folks shop.