Re: Foam Boat Constructio

Posted by Laszlo on Feb 5, 2006


Blue foam is not a structural foam. By the time you add enough glass and epoxy to it to make up for its weakness, you've lost any weight advantage over plywood construction.

There's also a potential problem of delamination. Since the blue foam is so weak, it can fail in shear. The glass can pull the outer 1/8 inch or so of foam away from the main core.

If you feel that you must use foam cores, you need something like divinycell, a closed cell PVC foam designed for structural use. It weighs between 3 1/2 to 8 lbs per cubic foot, depending on the grade, and costs anywhere from $80 to $800 dollars per 4x8 sheet, depending on the grade and thickness.

If I was doing this, I'd stick to wooden construction. You can make a very lightweight boat if you use monocoque construction (pre-stressed load-carrying skins) with minimal framing and thin skins reinforced with glass.

Good luck,


In Response to: Foam Boat Construction? by Jesse on Feb 4, 2006