J-B Weld MarineWeld is a specially formulated two-part epoxy cold weld system for strong, lasting repairs to alike or different surfaces, including aluminum, metal, composites, fiberglass, and more. It sets in 4-6 hours at room temperature to a dark grey color and fully cures in 15-24 hours. Once cured, it forms a permanent bond that can be shaped, tapped, filed, sanded, and drilled, maintaining its strength above or below water. MarineWeld has a 1:1 mixing ratio and a tensile strength of 5020 PSI.