Fiberglass boats are very susceptible to the damaging effects of the sun and the elements since the boats are stored and used in the open. Keeping up with any minor damage before it becomes a bigger problem isn't very difficult and can save a lot of time and money later on. One of the easier repairs is general fiberglass repair to the hull and deck of fiberglass boats.
Step 1 - Preparation
For precaution, wear protective gear. Remove the boat from the water and thoroughly wash the affected areas. Allow those areas to dry completely before attempting any repairs. Inspect the surface of the fiberglass boat's hull and interior for damage.
Any holes or scratches will need to be repaired using fiberglass patches and fillers. Use your drill or keyhole saw to cut out any of the damaged hull areas.
Use the course-grit sandpaper and the sander to smooth out the edges of the newly-created hole and taper the edges. Wipe down the surface with a rag and acetone to remove any dust.
Step 2 - Applying the Fiberglass Patch
Cut multiple layers of the fiberglass cloth, making each layer slightly larger than the previous layer. This will allow you to overlap a larger section over a smaller section, creating a more feathered patch on the hull.
Lay the smallest patch flatly on a smooth work surface. This is the first patch that will be applied to the fiberglass boat hull.
Mix the fiberglass filler and fiberglass hardener in an empty bucket until it reaches the manufacturers recommended consistency.
Apply the fiberglass mixture to the fiberglass patch using the paintbrush. Spread the mixture evenly over the entire patch. Take this first patch and apply it over the hole in the hull. Ensure the patch has plenty of fiberglass boat hull to attach itself to. Take the putty knife and smooth it out to remove any air bubbles and press it securely to the hull. Repeat these steps for the remaining fiberglass patches until an appropriate thickness has been reached. Use the putty knife to feather the edges of each layer as you apply it to the patch location.
Step 3 - Applying the Gel Coat
When you have added all of the fiberglass patches to the boat hull, apply the gel coat to the patch area using a paint brush or roller. Cover the patch and gel coat with plastic wrap and let it dry for eight hours.
Step 4 - Sanding the Patch
When the patch has dried, remove the plastic wrap. Start with the rough-grit sandpaper on your power sander and sand the patch smooth. Pay special attention to the edges of the patch to be sure they blend smoothly to the fiberglass boat hull and follow the contour of the hull.
Repeat the sanding procedures through each progression of sandpaper grit, finishing with the smoothest grit. Use a damp rag to remove any dust left over from the sanding.
Step 5 - Finishing steps
After you have finished repairing your fiberglass boat, you can apply a coat of marine grade paint to the hull of the boat. Apply this paint to the entire surface using the manufacturer's recommendations. Next apply a coat of the fiberglass wax and polish. The fiberglass repair will fix any of the damaged areas and the wax and polish will assist in preventing any future damage to your fiberglass boat.