: You will be far ahead if you plan it like there would be no core,
: paddle full of air. The insulation board has very low impact
: strength, the material will often fracture just below where it's
: bonded to the epoxy when stressed. Makes a nice light core to
: lay up upon otherwise.

: Bill H.

For years I built windsurfing boards using pink Foamula R for the core. I think it was the 150 not 250, slightly less dense. The boards came out as light as sandwich skin boards with expanded polystyrene foam cores, but if there was an injury, the foam, being closed cell, would not absorb water. They held up ok and had a slightly less rigid feel, lively but not dead. After a couple of hard seasons however there would be some areas that would start to delaminate. This didn't seem to happen with the extruded foams that are made for this, so I always wondered about the chemistry....Was there something in the Foamula foam that was responsible, or is that just the nature of the structural demands of the system? Was it chemical or just microfractures or shearing at the interface between the epoxy/glass skin and the one pound per cubic foot foam. A friend of mine recently built a beautiful camper insert for his pickup truck using this system as well. It's been road tested, and we're keeping our fingers crossed that he doesn't see delaminations starting....