Boat Fiberglass and Gelcoat Repair Guide

Hull repairs are easy with a fiberglass boat! Fiberglass is a robust material composed of glass fabric layers saturated with resin. You can repair any minor cracks that appear on the hull by patching them with an additional layer of glass fabric. This guide explains this method in detail, but we also recommend consulting the manual that came with your boat for more information.

Evaluating the Damage

Start by assessing the damage to your fiberglass hull. Try tapping a plastic screwdriver on the laminate and listening to the sound it makes. Areas that produce a less resonant sound are most likely delaminated. Once you have identified the areas that need repair, carefully remove the damaged sections of the laminate using a small, sharp blade.

Cleaning and Sanding the Damaged Area

For hull damage above the waterline, you can work from inside the vessel. Clean the damaged area with a dewaxing solvent to remove any residue. Then, carefully sand a beveled edge around the hole using a disk sander with 36-grit sandpaper. After sanding, wipe away the dust with a cloth rag dipped in acetone to leave behind a smooth, matte surface.

Preparing and Applying Laminate Backer and Wax

Next, apply a layer of paste wax around the hole in the laminate. Mask the area below the hole to prevent resin from dipping down onto it. Cut a smooth laminate or acrylic piece larger than the hole to act as the backing. Spray a polyvinyl alcohol mold release to the laminate, then fix it to the outer hull with screws or tape. You can use a heat gun to soften and shape the material.

Applying Fabric and Gelcoat

Apply gelcoat to the waxed backer, then dampen it with polyester resin as the gelcoat starts to set. Cover the area with layers of mat and fiberglass fabric, ensuring that each layer is about an inch smaller than the last. The number of layers will depend on the thickness of the hull, so continue adding layers until the repaired section is level with the rest of the surface.

Finishing Touches

Finally, cut a rectangular piece of mat and a slightly larger section of fabric. Place them over the patch, smoothing them out with a resin roller. Seal these layers with PVA and allow them to cure. Then, remove the waxed backer from the outside, fill in the gel coat paste, let it cure, and sand or polish the surface to achieve a smooth finish.

If you have any further questions about fiberglass boat repair, feel free to contact us. Looking for boats for sale? Visit Rockingham Boat in Hampstead, New Hampshire, to see what we've in stock. We are your local boat dealer proudly serving all those in Manchester and Nashua.