Attwood Clear Silicone Marine Adhesive
Bonds to fiberglass, plastic, glass, and metal making it perfect for installation of all thru-hull intakes and vent fittings. 100% marine grade silicone will not yellow or crack over time, and is suitable for use above and below the waterline.
Compared to 3M 4000, which is a popular alternative we sell, the nice thing about Attwood Marine Adhesive is that it dries completely clear, make it perfect use on colored gelcoat.
One tube it typically more than enough to install an entire ballast system consisting of 8-12 thru-hull fittings.