Originally Posted by Seakindly

SH - The last boat I rebuilt, I bought 2 part expanding foam from a private plastics lab, locally. I don,t know what West or BW sells. Point is they had foams of different densities. For flotation you want maximum expansion - say a 2gal kit yields 10 cubic feet. For bedding a fuel tank you want minimum expansion - say a 2 gallon kit yields 3-5 cubic feet.

Also use a mixing tool on an electric drill. If you mix by hand the foam will start expanding before you have finished mixing.

Be careful using this stuff in enclosed places under decks. The expansion forces are for real, and you can "blow your boat". :o