Plywood core in hatches

[Billybob]

FWIW, I used 1/2" BC or maybe even CDX plywood(don't remember) for my hatches and then Epoxy.I figured you don't need marine ply because it isn't going to get wet, and I didn't even know where to get it.Epoxy was recommended over polyester, because it soaks in better.My original coring was like a 2" x 4" sliced like bread and all the pieces laid side by side, presumably cause the end grain would suck up the resin better.Mine looked just like your pictures do, man that outer skin is pretty thin huh.I soaked the ply real good, let it set.Then I flowed it on to the back side of the skin, put the skin on a flat concrete floor,put in the ply, and then put a lot of weight on it so that the hatch would be perfectly flat, then I glassed the backside.I was concerned that the thin skin might set up a little twisted (or unflat) without the weight on it - they came out plenty strong and flat.I personally would go with epoxy - but I'm far from an expert.