: Hi Paul,

: I really like your sandpaper idea and I will use it.

Actually, not my idea. It was suggested on this board a while ago as a way of shaping a cedar board to fit the curvature of the deck to, I believe, mount a deck compass.

Originally I was going
: to fit layers of foam in the stern and bow before I mated the deck and
: hull, but because my deck was curling and cracking so bad I had to quickly
: put them together before anymore damage occurred. Now my plan is to blow
: up an air matress to put the kayak on to relieve hull stress while I craw
: inside and shape the foam in layers and glue them together.

Put the boat on an air mattress while you crawl inside to custom fit flotation? Why do you want to do this? It sounds too much like torture A bulkhead sealing an empty, hollow, space provides the same amount of flotation, and it weighs less, costs less, builds faster, and has less likelihood of damaging the boat. the compartment does not even need to be perfectly sealed. In fact, it is better if there is some provision for a small vent.

: . . .I once built an 18" box of plywood in
: around an epoxy coated model and I put in several 2" holes in the
: sides and back to let the two part foam expand through so the box didn't
: warp. It didn't work and the really strong box bulged on all sides. But
: the paper 1/2 gal container that contained the left over foam looked like
: an ice cream cone after the foam set up. . . This is
: what I picture happening in the bow and stern fill area's with the foam.

Well, you've already seen what happens to a wood "container" when that foam expands.

Again, though: Why bother? The general view here seems to be that sealed in foam is not the best way to go. Personally, I don't think it is even a very good way to go. No, let me focus that sharper: I think sealed in foam is a rotten way to build.

Eventually the foam WILL pick up some moisture, whether from humidity in the air, or from seepage through a minuscule leak. When that happens you find that you have to dismantle everything to dry out the compartment. And that is a REAL pain.

As I see it, the main "selling point" or "fear factor" that seems to drive the idea of foamed-in-place flotation is that the boat might crack, allowing water in, so that the boat capsizes. Or some similar scenario. But, if the boat *should* be damaged to the point where a solid foam flotation makes a difference (as opposed to a trapped airspace, or any other flotation), then it will definately need to be fixed -- and you'll have a harder time fixing it with that wet foam inside it.

If you want a solid flotation (as opposed to inflatable bags) strongly consider making your foam fit in loosely and be removable and replaceable. A bulkhead with an inspection hatch is a good option. Chopped foam in small mesh bags can be packed in by hand, and be removed quickly to dry before storage. (attach all the bags along the length of a single rope and pull on the end -- they all come out and yet stay together.)

Loose fitting, big chunks of foam that take up 50 to 75 percent of the area will provide a significant amount of flotation even if the compartment floods. Again, a hatch allows you to reach in and pull out these chunks should you need to drain and dry the compartment. You could even store spare PFD's as an alternative to a sealed in foam flotation.

Just a few thoughts.

PGJ