: One of the books said that a boat could be made with foam instead of wood has
: anybody done this?

Mr. Jardine's site has lots of good information on this type of core construction. Along the same lines, a lot of lighweight boat mfrs use a "honeycomb" material as a core, covered with carbon/'glass or 'glass layup. Many use vinylester resin/glecoat coverings etc. You'd need a mold like that of Mr. Jardine's. Heat curing is not necessary with vinylester resins.
Aside from a little weight savings, I cannot see any benifit in this type of construction for a "one-off" fabrication. .....now if you are going into the boatbuilding biz, well, that might be a different animal. The cost of tooling is spread out over your production, etc.
Those little honeycomb cells tend to fill with water when it gets damaged, and to keep that from happening means that you'd likely have to fill the damaged section with epoxy to seal it off (heavy), before re-glassing.
Anyway, foam core and honeycomb seems to be very common among mass production boats. But, a bunch of those guys use good ol' cost effective woodstrip methods for their prototyping.
Good luck with your project. Hope this is of some help.
garland