JEM Watercraft

I am building an 18 foot, 24 inch wide stich and glue rowing shell with enclosed decks that uses a Piantesosi drop in sliding seat unit. I want to pus some kind of flotation in the sealed off sections of the hull for and aft. I also like the idea of having a "solid" hull in case I hole the boat on a frequently encountered submerged stump. I have been thinking of layering some kind of closed cell spray foam like the kind builders use - "Great-Stuff" is one name brand. I know to be cautious of the foams expansion pressure deforming the hull as I blew out a bulkhead in a fiberglass version of a guideboat I built years ago.... Any thoughts/suggestions? Thanks Charlie

You should probably get direct input from the designer or site you're buying from.

But you don't want to use construction foam. It'll absorb water. Use marine grade expanding foam.

But sou should probably get direct input from the designer or site you're buying from.