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. Color: White.