: In the various plans and technique books that I've seen, I notice
: that all the composites are either wood covered in fiberglass,
: or non-cored 'glass & resin layups. Is there a good reason
: not to use a foam core? I'm looking at some of the stitch &
: glue plans, and seeing that it would be very easy to replace the
: plywood with 1/8" or even 1/4" Divinycell foam, then
: laying over a layer of kevlar, and layer of s-glass, then a
: couple of layers of s-glass and some strategic carbon for
: reinforcement. Would this not make a lighter-weight boat
: compared to the S&G? It would also be stiffer than a plain
: 'glass & resin layup. I understand there would be a price
: impact, but other than cost what are problems with this
: technique?

Unless you've got alot of experience using advanced composites, it will be very tricky using foam and it'll likely be quite a bit heavier rather than lighter. Strip built can be very light. You need much more fabric if you use divinycell since it doesn't have the compression strength that the wood does and that fabric/glass is the heavy part, the wood is actually very light.

As you mentioned it would also be very expensive.

Foam sandwich construction can be very light on a bigger boat, but as you get smaller the skin weight gets to be a higher percentage of the weight.

Fairly easy btw to have a sub 30 lb. 17' kayak using wood strip, very difficult to match that using other materials other than plywood with S&G.

Bill H.