Re: How to get from wood to gelcoat
The easiest way to patch the hole is to place something on the outside surface of the transom to use as a mold, Formica (counter top material) works well, you can also pick up melamine at a hardware store, its plastic coated would.
You need to grind the inside surface of the transom and taper it out to a fine edge around the hole.
The mold surface needs to be waxed before putting it in place, it can clamped, screwed or whatever works best in your situation, but it needs to up tight and solid.
If you have some gel coat that matches your boat (it won't really, due to age) you can catalyze it and brush it on the mold surface. You need to get it fairly thick, so sometimes it takes a couple of coats to get complete coverage. Then wait for it to get hard.
You then glass it from the inside, cover the mold surface you put in place and out a few inches around it, two or three layers is fine and depends on the type of glass your using, but try to match the thickness of the surrounding glass.
When that's hard you can pull the mold surface off.
You can now add plywood on the inside or whatever you plan to beef up the transom with.
The outside of the transom will now have an odd looking outline of the hole, it may be perfect (don't count on it) or may need some work (expect this). You'll need to fill the imperfections, they may be small or large, this is where the filler comes in. Gel coat can be used for small stuff, but it can be harder to sand on a large area. You may also need to use a long board to sand it if you want it to look near perfect.
Now you need to decide whether you want to use gel coat or paint, neither will match the surrounding color so you'll need to at least do the entire transom.
