3M Marine Adhesive Sealant 5200 3Ms 5200 Adhesive Sealant is a one-part polyurethane used for permanent bonding. 5200 offers permanent adhesion to wood, gelcoat, and fiberglass, and forms watertight seals. Designed for the marine industry, this sealant forms bonds that are resistant to saltwater and weathering. This sealant is flexible, allowing for structural movement and dissipation of stress that may be caused by vibration, swelling, shrinking or shock. 3M 5200 achieves handling strength in 4