What was used on this engine cover?

I have coffee colored water running out of the bottom of the engine cover so I removed the fiberglass to get at the plywood underneath to replace and I have to use a chisel and hammer to pry the wood from the glass in little pieces?The cover is 34 years old would this be epoxy? I would like the same kind of adhesion when I put the new piece in.

 

That is polyester.

 

I can't tell what adhesive they employed on your boat, but it's unlikely epoxy. Polyester is very probable as Gonzo mentions. Clearly you need a new engine cover core (plywood), as you appear to have carved through at least two layers of plywood veneer. If the remaining plywood is flat enough and still stiff, consider applying a 1/4" layer to the underside to reinforce what you've removed and further stiffen up the cover. I'd recommend epoxy rather then polyester and use a heavy aluminum oxide powder mixed in when you apply the thickened bonding coat.

If the plywood core is shot (wouldn't be a big surprise) then knock and grind out the remainder and epoxy in replacement pieces. Again with a heavy aluminum oxide, milled fibers and silica mixture.

 

Its all carved out (I wasnt all that bad, to late now).When I would lifted the cover it would drain coffee colored water out the bottom lots of small cracks some areas where rotten but most was very wet.The fiberglass skin that covered the plywood on the underside is reusable.I was thinking I have some System Three G2 epoxy? I can apply to both sides of the new plywood and cover with the fiberglass skin ,lay flat, place weight on it on a level garage floor cure then reinforce fiber glass on the outside of the original skin will this work with the epoxy on the inside and poly resin,cloth on the outer cover to tie it all in cover the cracks? I dont have enough epoxy to do the ouside.

 

Polyester doesn't stick well to (over) epoxy, so do all your polyester work first, then finish with epoxy, which sticsk to polyester better then polyester itself.

 

Thanks,good info,appreceate it.