How to Repair Gelcoat Cracks

What You'll Need
Painters tape
Gelcoat repair kit

Gelcoat is a fiberglass resin that has had a pigment added to it. This resin can be used as a protective surface over the top of fiberglass, or simply as a finish, much like you might varnish a piece of outdoor furniture. With time, it is possible that gelcoat can become cracked, simply through wear and tear or a specific incidence of damage. It is possible to fix a crack in gelcoat easily, as it can be sanded over. If you feel like giving this repair a go and have some experience with home improvement techniques, follow a few simple rules to help you complete this job.

Step 1 - Preparation

Carefully sand the crack or cracks. Using sandpaper, you should be able to sand thoroughly into the depths of the crack so that the edges are smooth. You should add a layer of scuffing to the cracks at a wider point than you would need. The next thing to so is to carefully sand the surface of the repair using a rag and some acetone solvent. Wipe away any other dirt and debris that is laying close to the crack.

Step 2 - Mixing the Gelcoat

Before you add the gelcoat to the cracks, you will need to protect the area around them using painter's tape. This tape will peel away without sticking, so you can remove it without worrying that you may be damaging fiberglass resin beneath it. The tape will help to ensure that your fresh layer of resin doesn't go too far across the surface. Now that the cracks are ready, mix your gelcoat repair kit and the hardener together. Take care that they are completely mixed together, otherwise the hardener and gel coat will not set properly, and you will be left with a sticky mess for weeks.

Step 3 - Adding the Gelcoat

Once you have mixed the components together, apply them to the surface using your roller. Be sure to roll backwards and forwards in an even stroke, so that you don't put too much of the coat in one place. You may cover the cracks with just one application, but make sure that the product is sunk completely into the cracks before you consider that you have finished. If the gel coat does not completely cover the coat in one stroke, you should allow the first coat to harden into a sticky lump before applying a second mix. Once you are satisfied that it is completely saturating the gaps, leave the resin to harden.

Step 4 - Finishing

Once the resin is hard, you can take the sandpaper to the top, and smooth over the edges of the fiberglass until it forms a completely even surface with the surrounding parts. Remove the masking tape and sand down the sides there so that you have a flat edge. You may also like to buff the surface of the resin in order to give it a more uniform appearance, matching the rest of the fiberglass on your boat.