Bostik 920 urethane sealant is a single part, gun grade adhesive/sealant that moisture cures to form an extremely tough, waterproof, permanently flexible seal. It is specially formulated for outstanding performance in critical boat-building and repair applications. Sealant retains its strength above or below the waterline! 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 waterline. Stays flexible and allows for structural movement. 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; Portholes and deck fittings; Motors on fiberglass transoms; Under mouldings; Hull seams above and below waterline; Center board trunk joints; Between struts and planking. Stern joints; Deck housing, etc.; Easy to apply with manual caulking gun; Remains workable with trowel or spatula up to four hours after application; Won't sag or flow in vertical or horizontal seams.