: Our friendly local kayak shop has 12"x24"x3" chunks for $15.
: This was a better than our larcenous local foam shop, which wanted more
: like $25 plus a stiff cutting charge, and didn't know exactly what kind of
: foam it was.

: I installed foam bulkheads in a S&G in '95 with 3M 5200 polyurethane
: caulking, and it's still going strong. Tape off any place you want clean
: though, once it's on it's pretty much there to stay.

Three inch mini-cell gives plenty of contact area, when you have the bulkhead fit in place jam the caulk spout between the foam and boat and work it all the way around. Finish up with a bead around the corner for a final seal. 3M 5200 works great.
Bill