Ed,

I'm sure that your local foam supplier (see the yellow pages) can get the
foam you need. I went to the one here, "The Foam Man" in Corvallis, Oregon,
and bought several sample of different types of closed-cell foam to test
them. I weighed each piece ahead of time (dry) and measured the dimensions
(rectangular pieces). Then I tied each one to a brick and dropped it in a
bucket of water where I left it for 8 months out in the shop, filling as
necessary to make up for evaporation. With all the dust in the shop and
mosquitoes trying to set up shop in the buckets, there was slime and
who-knows-what growing in it ...short of using seawater and tossing in some
oil and gas, I figured this was a pretty good emulation of a typical bilge
where you might add flotation. After the 8 months, I took the blocks out,
brushed them with a potato brush under running water to remove slime, padded
'barely dry' on the outside with paper towels just to get rid of sheet water
on the foam, then weighed and measured each piece.

I forget now all the types of foam that I tested, but the clear winner was
closed-cell polyethylene (blue). They all absorb water over time, but the
blue poly only gave up 3% of it's flotation capability (3% of the displaced
water) and only swelled up about 3% in volume too. I followed this test by
putting the blocks of foam in Ziploc bags for a couple of weeks, one end
left open, to emulate a little trailer time for 'drying'. The blue poly was
still wet and there was lots of condensation in the bag after a couple of
weeks (not very good ventilation in/out of the bag), but the poly had given
up half the absorbed water anyway.

My conclusion was that the sealed-cell blue poly was an acceptable
flotation foam. In my case, I was looking for something that could be cut
to fit and installed, but could still be removed later on. Can't stand that
expanding polyurethane foam ...everybody that I know that has used it in
their boat has reported that it eventually becomes water logged and sloppy.
It is best used in compartments that normally stay dry, not wet.

Hope this info helps. For my boat project (see
http://www.reelboats.com ), I'll have cut-to-fit sealed-cell blue
polyethylene foam in the closed compartments, and will be able to remove the
foam via large rectangular deck plates installed in the bottom of cabinets
(not accessible to water on the deck ...deck plates leak). I'm going to run
a nylon strap or rope through the first block that goes in so I can pull the
blocks back out later on. It'll push the others towards the deck plate as I
pull it out.

Brian D




"Ed Lindsey" wrote in message
...
Hello,

Does anyone know of an inexpensive sheet foam suitable for use as
flotation? Possible sources in the western US?

Thanks