Sikaflex 291 is a professional-grade adhesive used by boat builders to bond boat components structurally. It is graded for marine applications and will bond to full strength overnight. Sikaflex 291 can be used both above and below the water line. It comes with a nozzle and is available in small tubes. It is available in both black and white. Applying Sikaflex291 is no different than applying any other type of silicone sealant, and when completed correctly, it can have a lasting impact on your boat.
Slide the tube of Sikaflex 291 into a caulk gun. Push down firmly and lock it into place. Cut off the tip of the nozzle with a utility knife near the top. Cut at a slight upward angle with the knife.
Line up the sealant at the desired location on the boat. Hold the front of the caulk gun with your non-dominant hand. This will help guide the sealant when it is being installed. Press the trigger on the back of the caulk gun with your dominant hand.
Run a thin bead over the seam or other desired location. Continue over the entire surface until a thin and even bead covers the area. Wipe away any excess sealant with a clean rag, being careful not to touch the sealant that is in place.
Inspect the sealant after it has had one hour to get tacky. Add more in certain locations, if necessary, and let it dry overnight to completely harden and gain its strength. Repeat the process for any of the other areas that need to be sealed.