Has anyone used styrofoam as a core for an engine hatch? Can it be used?

I'm pretty sure it will melt when the risin hits it

Yep, just like gasoline....

It depends on the type of foam and the type of resin. Not boat specific but I've used foam cores for RC Air raft wings that were glassed, no melting of the foam. Surfers have been doing it forever as well.

Eps and epoxy resin are compatible as far as I can recall

Ryan

I'd think some plastic sheet between the two would protect the foam from the uncured resin if there were compatibility issues.

He said styro it will melt with any Ester resin.

Hey Dean, did you get your cylinder rebuilt? The reason I'm asking is I just took two older mayfairs apart and they were a ***** to disassemble. Looks like somebody was too liberal with the red Loctite on mine though.

You should use a structural foam such as Airex or Coosa, etc.. They can be used with either polyester, vinyl ester, or epoxy. Styrene foams are generally too weak and will melt with the styrene monomer that is in polyester and vinyl ester. And, no, you do not want to put a sheet of protective plastic between the foam and resin/cloth layup as this would prevent the bonding of laminate and foam which is key to creating the strong I-beam structure. The engine hatch cover needs to be a stiff structure for obvious reasons, so it would be foolish to cut corners on laminate schedules. Do use vinyl ester or epoxy with the proper foam core as they are far superior to iso polyester.

Great info, thanks for the input ren3.

Ok so structural foam is best.