: The other thing I soaked under water for two weeks is blue building foam. I
: had always though of using it in the bow and stern for floation, but the
: consensus seem to be that it would water log. This doesn't seem to be true
: in my experiment. I weighed the soak foam this morning on gram scales
: along with an identical non soaked foam piece and they both weighed the
: same. So in my next boat I am going to use it as floatation.

While it is unlikely that any of the foams would ever absorb so much water that they would sink, nonetheless, they do absorb some. So does wood for that matter. The amounts are so small that very precise scales would be required.

Worse than absorption, though, is that the texture of the foam material tends to trap small quantities of water (droplet size)right on the surface. There is just enough water trapped to feed those pesky mildew spores, and to promote rot in unprotected wood. The trick is to leave enough room around the foam for air to circulate. That way the foam can completely dry out.

If the foam is permanently sealed inside a closed area you have no easy way of drying it out. Why not make your flotation out of 5 or 6 tapered pieces of foam which can fit through an off-the-shelf 8 inch diameter hatch, installed in a bulkhead. When all are inside they fill the area, but when you open the hatch you can remove the foam in sections. Cut the foam pieces so they interlock, or key together, like the molds for plaster casting that were discussed a while ago. If you are paddling on weekends, take the foam out on Sunday night when you store the boat. And of course you remove it at the end of the season. The large opening for the hatch lets the boat dry out, and the foam blocks will dry, too, once they are removed from confinement.

With this method you can use the area for extra storage should you need it, too.

Hmm. Depending on how you arrange the foam you just might create a nice cooler for some beverages.

PGJ