DCYC Gelcoat Repairs

The next time you're cleaning and waxing your boat, take the time to look for small cracks, scratches and chips in its gelcoat. If your boat is more than a few years old, you'll probably be surprised at the number you find.

The Diagnosis
The sources of most scratches and chips in gelcoat are not cause for concern, but if you find a series of cracks, take a minute to inspect the area more closely. If the cracks radiate from the base of a piece of load-bearing equipment like a cleat or stanchion, there is probably a problem with the installation that deserves attention before repairing the gelcoat. Solving it might be as simple as shifting a load from undersized equipment, or installing a larger backing plate to spread the load over a wider area. If cracks appear at important joints or intersections in the cabin or deck, however, they might be the sign of an underlying structural weakness that needs to be examined.

The Repair
Before you begin, wash the area with soap and water and rinse it thoroughly. If the surface is oxidized, restore it with a rubbing compound so you'll be able to match its color accurately. Once the surface is clean and dry, mark off the repair area with masking tape.

Next, small, narrow cracks (and scratches that are too deep to remove with rubbing compound) should be gouged out until they are wide enough to fill with gelcoat paste. A miniature grinding tool like a Dremel is ideal, but the sharp point of a can opener can work, too. The damaged area should then be lightly sanded with 220-grit sandpaper. When you're finished sanding, thoroughly clean the area with acetone to remove the sanding residue and any waxes or other contaminants that might interfere with the bond between the damaged surface and gelcoat (make sure to provide adequate ventilation and proper protection for your skin and eyes whenever you work with acetone).

The next step is to match the color of your existing gelcoat. Start with a white or neutral gelcoat paste (not resin) and begin adding tiny amounts of coloring agent. Mix several test batches of gelcoat and pigment, add hardener and allow to them cure (gelcoat changes color during the curing process). Once you've found an acceptable match (an exact one is nearly impossible), mix a final batch using the same ratio.

Next, using a putty knife, fill the areas to be repaired with the paste you've mixed. Make sure to force out any air holes and be sure to overfill, as gelcoat has a tendency to shrink as it cures. When you're finished filling, you'll need to seal the repair off from the air with a PVA curing agent or a piece of Saran Wrap or wax paper-gelcoat does not cure properly when exposed to air.

Once the gelcoat has fully cured, sand the repair smooth (wet sanding works particularly well with gelcoat). You can start with 220-grit sandpaper and, for a really slick surface, finish with at least 400- or 600-grit. Finally, apply a coat of high-quality marine polish and your repair is complete.

 

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