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Originally Posted by rebel heart  If I get a piece of plywood, would I "marine treat it" somehow? |
Yes, with epoxy.
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Originally Posted by s/v Jedi Rebel: you don't. Cut the 12" hole and check the wood; keep cutting it bigger until you find good wood without rot. Now bevel it to 12:1 so that the outside diameter is the bigger one, using plane, router, beltsander etc). Now take 3-ply plywood, cut roughly to shape and have someone push it onto the hole from inside. mark it from the outside. Enlarge the markings to half the 12:1 bevel size and cut. It will now fit in there, with the edges halfway the thickness of the cabin-top. See if you can compound it a bit to have the same curves, practice a bit how and where to push. Now, wet the bevel and 3-ply edge out and mix a batch of thickened epoxy, using medium density filler to peanut butter consistency. When the wet-out starts gelling, apply epoxy generously, push the panel in and do the pushing/compounding for best shape while tacking the edges in place. Remove excess epoxy with rounded end of stick so that you leave a little fillet in place. Let cure.
Now, you build both outside and inside up using fiberglass cloth or woven roving if thickness allows (every layer on outside bigger cloth, inside smaller to fill up bevel) and find a fairing-wizard for final looks or try yourself with long thin batten. Sand, paint.
All but the fairing and painting part is easy. I succeeded with similar projects without ever having it done before. I did have some fiberglass experience like building model airplanes but nothing special.
cheers,
Nick. |
I tend to agree with SVJ here but what is the thickness of the ply you replacing?
If greater than say 3/8", I would laminate up the new piece in a similar way to SVJ but use say two or 3 pieces of 3/16" etc.
I would ONLY use marine plywood regardless of what others say about epoxy and commerical ply. The amount of labor is significant so why mess around with a second rate material.