Anyone tried to CNC cut an entire styrofoam hull plug, epoxi/glass the outside and then dissolve the styrofoam with a solvent? Do you think it would work?
Leave the foam inside the hull: unsinkable boat

I think the right way to proceed would be to make two half hull plugs, build molds around those, and then build hulls from the molds.
This said I've seen recently a web site from a Acat build who made his carbon hulls directly from CNC plugs. Can't find it at the moment however...