3M MARINE ADHESIVE SEALANT This high-performance polyurethane adhesive/sealant becomes tack free in 48 hours, completely cures in 5-7 days with no shrinkage. The seal is extremely strong, retains its strength above or below the water line. Stays flexible too and allows for structural movement so stress caused by shock, vibration, swelling or shrinking is effectively absorbed. Has excellent resistance to weathering and salt water. Check the bonding and sealing jobs this product can handle for you: fiberglass deck to fiberglass hull, wood to fiberglass, porthole frames and deck fittings, under mouldings, hull seams above and below water line. Stern joints. Deck housing, etc.