3M Marine Adhesive Sealant Fast Cure 4200FC is a one-component, medium-strength, moisture-curing, gap-filling polyurethane that delivers strong, flexible bonds to aluminum, wood, gelcoat and fiberglass. It forms watertight, weather-resistant seals above and below the waterline. In addition, its flexibility allows for dissipation of stress caused by shock, vibration, swelling or shrinking.