> If you have your decks on already then I'd suggest making a mold,
> lining it with some sort of release (I'm on shaky ground here as to
> what would work - maybe sheet plastic?) pour a plug of the foam, trim
> it, then install it as a removable component of the boat.

Mind a suggestion? First poke a plastic garbage bag into the cavity you want to fill with foam. There are plenty of sizes to chose from. A tire pump, several good hard puffs if your lungs are in shape, or the exhaust from a vacuum cleaner will inflate the bag to roughly fill the space. Put the foam into the bag. After it expands, use a piece of copper wire as a twister to seal the bag.

Doing it this way the foam won't stick to the boat, so it is removable and the plastic serves as a water and vapor barrier to slow absorption of moisture by the foam.

If you are thinking of putting flotation in an area that is easily accessible, consider getting or making a fabric bag ( for resistance to abrasion) lining it with a plastic garbage bag ( for water proofing), and filling the combination with foam packing peanuts, or chunks of molded packing foam. This flotation is free and can be pretty durable. If the plastic bag is punctured it may get soem water inside it, but the water will hardly affect the flotation. If it gets moldy or mildewy after a few years, wash out the fabric bag with some bleach, dump the plastic bag and foam chips, and start over. For small diameter float sacks like this, which can easily pass thru hatches, consider recycling pant legs from old jeans. To make a sack from them you just have to sew up the ends.

Paul Jacobson