[tartuffe]

It's a bad design. The wood is a structural component. The foam will never dry out. I had my entire top pulled off and out of the weather and 3 months later it was still sopping wet. You will probably find heavy pitting in your fuel tank on the underside if you pull it out. Aeromarine has great prices on epoxy resins (I prefer epoxy over polyester or vinylester de
spite the cost, its more forgivingto the beginner and a superior product) and foam. Fiberglass supply has very good pricing on fiberglass cloth. 12 oz biaxial 45 degree material could be used to reinforce stringer to negate loss of wood strength. A solid bond to exiting polyester resin is critical. It's a mess you have but a fairly easy fix but it will take some time and several hundred to get it right.