: I was wondering why I didn't have the same problem with my kayak
: then i realised the buoyancy chambers are foam-filled. Wouldn't
: that be a simpler solution? The insulating foam sheets for house
: walls is very low density and the gaps could be filled in with
: the spray stuff . . .

Actually surprisingly, the weight of the foams adds up. Most styrofoam insulation is about 2.2 lbs/ft. To float a kayak, cockpit full of water and the average person you'd need around 6 cu. ft. of foam and that's nearly 15 lbs. When you start with a sub 40 lb. kayak it's a bit of a crime to make it a 55 lb. one and then you have no storage at all and the bulkheads still need vented.

Bill H.