Abstract: The invention generally pertains to the use of polyurethane foam blown by at least one blowing agent having a boiling point at atmospheric pressure of between ˜?50° C. to less than ˜5° C., including miscible blends thereof, which passes all United States Coast Guard Title 33, Part 183 specifications wherein the buoyant force of the froth polyurethane or polyisocyanurate foam is not reduced more than 5% after exposure to being immersed in a fully saturated gasoline vapor atmosphere, in reference fuel B, in reference oil No. 2, and in a 5% solution of Na3PO4.