How to Fiberglass a Boat Hull

Clean the wood surface of the boat where you will apply the fiberglass. Wipe the surface clean with a damp cloth and allow it to dry before applying the fiberglass mixture.

Mix the resin and hardener together in a plastic bucket or container following the recommended ratio of hardener to resin and the recommended amount on the packaging (different kinds of polyester and epoxy have different mixing ratios). Do not apply a different ratio or amount from that listed. Mix the two compounds together using a wooden stirring stick. Place the bucket in a cool, shaded area. The mixture will produce an exothermic reaction, giving off heat. The larger the amount, the faster the reaction, the hotter the mixture will be and the faster it will cure.

Apply a coat of the mixture to the surface of the boat hull. Paint it on thinly and evenly with a back and forth motion using a wide paintbrush or paint roller. Leave the coat for 15 minutes and return to inspect the surface for dry areas or areas where the wood has absorbed the mixture. Reapply a thin coat over this area. Leave the hull to cure over night.

Apply the fiber glass cloth onto the cured surface of the hull. Position the cloth so that no gaps occur. Apply the resin mixture over the surface of the cloth using a paint roller. Push the resin into and over the cloth. Move the resin over the surface, stretching it as much as possible. Avoid applying too thick a coat of resin. The resin should be absorbed by the cloth, giving it a translucent mat appearance. Allow a few hours for the fiberglass to cure. Once the surface is dry, you can apply another coat.

Apply another coat of the resin mixture over the fiberglass using a paint roller. Apply the mixture in an even and thin, back and forth motion. Use a paintbrush to even out any thick or runny areas. Allow this coat to dry for a few hours until the surface is no longer tacky.

Apply one more coat of resin mixture following the same procedure as step 5. Leave the fiberglass to cure over night.

Sand the surface of the hull to remove any bumps or imperfections from the resin and to rough up the surface. Apply marine paint or varnish over the fiberglass in even, back and forth motions using a paint roller. Allow the paint to dry.