Hi-

I had thought about doing something similar on my Greenland skin-on-frame. I posted the question to the Baidarka list, and the responses seemed to indicate that the foam is not waterproof, and would soak up water and become a soggy mess.
If the foam is encapsulated, this could be avoided. But then the casule would be your flotation and who needs the extra weight of the foam?
I ended up putting left-over pieces of minicell into the stems, and went with float bags. The Mariner Kayaks guys sell some real nice large bags out of a very tough material. Recommended!

Good luck-
Jack

: Hi Rehd,

: I am building a self designed Kayak similar to the Little Auk as my first and
: I probably won't have any hatched compartments for bouyancy, so I am going
: to keep your idea in mind. I orininally mentioned that I was thinking of
: pouring expanding foam into the bow and stern as floatation, but was
: warned that this might put too much pressure on the boat's structure and
: cause damage. I had worried about this also, because when I was in pattern
: making I once used expandable foam as an experiment to back up a pattern.
: I boxed the back with 1" plywood with 2" holes in it for the
: foam to flow through and not deform the square back, but it did anyway.
: This foam expandsion was probably 10 or 20 to 1. However, I think I recall
: mixing a batch in a gallon paper mixing container to see it's reaction and
: it only foamed up out of the container without deforming it in any way. If
: I remember this correctly, and I would run this test again before trying
: this on a kayak, then I have in mind, standing the kayak on its nose
: veritcally and making my pour through a garden hose with a funnel attached
: to the pouring end.

: John