and
would need to incorperate some connection system to bind the 2
layers of glass together, unless you trust it to adhere strongly
to the foam while sloughing off 10 tons of lumpy seawater

Interestingly, I've just started working for a company specialising in
attaching resins to many substrates including foam. And I _really_
would trust it to adhere to the foam. I could give you a recipe for
adhesion to of all unlikely substrates, polysyrene, were it not
commerically sensitive.

Al