Repairing the fuel tank hatch
I have done some minor fiberglass repairs in the past filling in where prior owners had poked holes and have been following "Boatworks Today' with Andy Miller and had a good sense of what I needed to do for the repairs.
I decided the first thing I'd tackle as a bit of practice would be to remove the rotted plywood from the fuel tank hatch and replace it and to fill in the holes.
Working from the back to preserve the top layer of glass, the fiberglass was cut around the edge of the plywood using a multitool. That was easily peeled off and the rotted wood removed. Using the top as a template a new piece of marine plywood was cut to fit.
Repairing the fuel tank hatch
Here the back layer of glass has been peeled off and you can see the plywood core. All the dark areas are wet rotted wood. And of course around the large opening is good old 5200. You should have a license to use that stuff.
Repairing the fuel tank hatch
Since the original layup was done with polyester resin, I used that for the repairs. Luckily, I was able to remove the old plywood without damaging the top of the hatch.
First, a layer of chopped strand was laminated to the back side of the top of the hatch. A new piece of 1/2 inch marine plywood was cut to fit and epoxied in and left to cure. After that was set up, 3 layers of 1708 were laminated to encase the plywood, bond to the top around the edges and the holes on the top were filled using 1708 built up to match the original thickness of the top.
You can never have too many clamps and assorted objects to hold down the plywood to the first layer of glass and epoxy.