No, don’t just
plug the hole or stick something in. At best you create a hard spot which is bad enough not to do it.
Here is an easier method that still does it right, assuming access to both sides:
1 put plastic
food wrap on a thin piece of
plywood, drill and screw it to the outside of the hole. Now fill the hole with
epoxy fairing compound from the inside. Just flush with the laminate.
2 after cure and removing the board and plastic wrap, the grinding starts. Draw the 6 to 1 circle and try to imagine the area as a cupped area with the center as deep as halfway down the laminate. Use a drill or grinder to mark the center to half the thickness so you know where to stop grinding. Grind it out. I like to start with a small angle grinder (Makita 5” is the tool of choice because it’s lightweight) and a so-called stripper disc. The disc quickly wears out the outer edge, creating the perfect domed shape for this. Finish with 80 grit on a small random orbital sander.
3 cut circles from 1708
fiberglass. You can stack them to see how many layers you need: thickness doesn’t change much. Yes I like to start with the biggest one. Test with a flexible batten if another layer is needed but don’t go too thick. End with some epoxy with cabosil, trowel it on and use the flexible stick to form it to the shape of the hull. Then get the thin piece of
plywood out, cut a circle somewhat bigger than the patch and drill and screw it down around the patch with new plastic wrap. Let cure.
4 remove
wood and plastic wrap and say ooh and ahh. Countersink and fill screwholes with some thickened epoxy, then wash with
water and soap, then sand with 80 grit ready for barrier coat and
anti fouling.
5 repeat same for inside. The new
fiberglass in the center is now the
depth gauge. Finish with barrier coat without the antifouling
The trick with filling the hole first makes it very easy to grind and
layup and screwing the
wood down prevents the need for fairing.
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