How to Fiberglass a Boat Hull

Updated April 17, 2017

Applying fibreglass to the hull of your boat can prolong the life of your boat while protecting the wood from water, weathering and rot. Fibreglass is a strong artificial material that will not corrode or rot and forms an airtight bond on the surface it is applied to. Although fibreglass is a hazardous material, it can be applied at home as long as proper safety precautions and procedure are used.

Clean the wood surface of the boat where you will apply the fibreglass. Wipe the surface clean with a damp cloth and allow it to dry before applying the fibreglass 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 fibre 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 fibreglass to cure. Once the surface is dry, you can apply another coat.

Apply another coat of the resin mixture over the fibreglass 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 fibreglass 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 fibreglass in even, back and forth motions using a paint roller. Allow the paint to dry.


Apply the fibreglass in a shaded, sheltered location free of direct sun, moisture and dirt.


Epoxy fibreglass and polyester fibreglass are toxic and hazardous compounds. Wear goggles or other eye protection, gloves and non-permeable clothing for protection, such as plastic or paper aprons.

Things You'll Need

  • Fibreglass resin
  • Fibreglass hardener
  • Wooden stirring stick
  • Paintbrush
  • Plastic bucket or container
  • Paint roller
  • Fibreglass cloth
  • Sandpaper
  • Marine paint or varnish
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