Commonly called blisters on the boats hull bottom, it is also known as hydrolysis. This condition is caused by the fiberglass being in constant contact with water without a proper Epoxy Primer barrier-coat to protect the fiberglass boat hull. Left unrepaired, these blisters increase in size and weaken the bottom of the boat hull.
Most fiberglass boat hulls are made of General Purpose Polyester Resin. A few boat builders use Vinyl Ester resin that cost twice as much as General Purpose Polyester Resin. Visit our fiberglass materials catalog to learn more about Vinyl Ester Resin. When repairing osmosis blisters Captain uses Vinyl Ester Resin to make Fiberglass Boat Repair below the water line. Fiberglass Swimming pools share the same problem. High end fiberglass swimming pools use Vinyl Ester resin. Low-ender’s use Vinyl Ester Resin only in the first laminate of fiberglass fabric behind the polyester Gel Coat known as a skin coat.
The Captain prefers to use Epoxy Resin to make Osmosis Repair if the fiberglass boat can not be out of the water for a period of time to dry out the moister in the Osmosis repair area. Epoxy Resin cost twice as much as Vinyl Ester Resin. The Captain’s choice for Epoxy Resin Osmosis Repair is DYNAPOX manufactured by DYNAMIS EPOXY SYSTEMS. DYNAPOX is a marine laminating system that yields high strength, 100% solids low viscosity system with excellent wetting and anti-sag qualities and great adhesion properties. Easy to use 2:1 mix by volume and the big plus is it provides a thin film that cures with little to no blushing.