3M ™ Marine Adhesive Sealant 5200 is a one-component, high-strength, moisture-curing, gap-filling polyurethane for permanent bonding of wood, gelcoat and fiberglass. It cures to form a firm, rubbery, waterproof seal on joints and boat hardware, above and below the waterline. This product has been trusted throughout the marine industry for over 50 years. 3M ™ Marine Adhesive Sealant 5200 is designed to meet the high demands of the marine environment, making it ideal for creating tough bonds resistant to saltwater and weathering. We formulated our sealant to provide an exceptionally strong solution for marine conditions as well as flexibility that combats vibrations, swelling, shrinking or shock. Once again, despite the barriers of a rough marine environment, 3M looked to science to provide a reliable, durable solution.