Filler Up

Posted: July 1, 2013

Here’s what to do if your boat has more holes than a slice of baby Swiss.

By: Capt. Wilson J. Sheppard

Similar to putting off a visit to the dentist, avoiding corrective repairs to your boat can literally result in pain. For my wife, the pain (and a rip) occurred because I decided it was easier to install a new VHF antenna in the same place the old one obstructed the starboard sidedeck, which meant I had to relocate the antenna or she was not going to the bow to deploy the anchor or pick up a mooring. She could have used the port-side deck, but she wanted to make a point — and when the Admiral speaks, the Captain listens.

Removing the antenna left nine screw holes in the fiberglass that needed to be filled, sanded and blended into the existing gelcoat. Fortunately, you can perform minor fiberglass repair without too much physical or financial pain.

Prep Talk

There are several options available for small repairs to fiberglass. Conduct some in-store and online research to determine which option best fits your situation. Instead of buying all the needed supplies separately, I purchased the Evercoat Match n’ Patch Gelcoat Repair Kit from West Marine for $48.99. The kit included polyester gelcoat resin, hardener, color pigments, mixing cups, stir sticks and other supplies needed to perform the repairs. In addition, I planned to use some leftover resin, fiberglass cloth and hardener from another project to fill the holes.

Before actually performing the repair, be sure to clean the repair area thoroughly. Start by washing it with an environmentally friendly soap, and then scrub it with a sponge to remove any dirt, grease, wax, etc. Give the surface a few minutes to dry before wiping it with acetone using a clean white rag. When working with acetone, be sure to use protective eyewear and chemically resistant gloves. Rinse the repair area again, and allow it to dry completely.

Mix It Up

To prepare the resin for filling the holes, pour it into a small cup. If you’re using a paper cup, be sure it doesn’t have a wax coating that could contaminate the mixture. Use slightly more resin than necessary, to avoid having to prepare another batch.

To match the color of your existing gelcoat, follow the color-mixing instructions provided with the repair kit. Add a base color to the resin, and mix thoroughly using a clean wooden stir stick. Add one drop of tint at a time, and mix it thoroughly. Spread a small sample of the colored resin on the repair area to see if it is similar to your existing gelcoat. If not, wipe away the sample and add another drop of tint to adjust the color of the resin. Add tint sparingly, or you risk ruining the mixture and having to start over. Depending on the age and condition of the gelcoat, an exact match may not be possible, but a close match can be blended into the surrounding gelcoat. Because my white hull has turned off-white over the years, I added a few drops of black to “age” it a little.

Once you have created the desired color of resin, closely follow the instructions for adding hardener to the resin. Keep in mind when adding the tint to match your gelcoat that adding hardener darkens it slightly. Thoroughly mix it into the resin. You have about 15 minutes of working time to apply it before it starts to set.

Use the wood stir stick to apply the resin to the holes. Poke the holes with the stick to force the resin into them. Apply more resin over the holes until they are filled. Add a thick layer of resin to cover the filled holes.

When the resin is stiff but not fully cured (about an hour), lightly sand the area with 80-grit sandpaper, which will rough up the area and remove some of the thick layer. Use 220-grit sandpaper to smooth out the repair area and to blend it with the surrounding area.

Gel Time

For the final finish, I used West Marine Finish Gelcoat ($37.99/pint), styrene thinning agent ($14.99/quart) and a Precision Valve paint sprayer ($7.99). Follow the mixing instructions to color the gelcoat to match your existing gelcoat. Add colors sparingly and mix thoroughly, as described previously. When the desired color is achieved, thin the mixture using styrene. The thinner should not be more than 20 percent of the amount of gelcoat. Last, add the hardener as directed in the instructions.

Pour the mixture into the Precision Valve bottle, and secure the bottle to the spray canister. Apply the gelcoat using a smooth sweeping motion. If you decide to apply multiple layers of gelcoat, allow time for them to dry and sand between spraying.

Once the gelcoat has been applied and has cured, lightly sand the repair area with 220-grit sandpaper. Follow that with 400-grit and then 600-grit wet sanding. For finishing touches, buff, polish and wax the repair area.

You can use this fiberglass repair technique for a variety of applications.

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