How to Fix Light Gelcoat Scratches

Used boats often have scratched gelcoat. If you’ve been shopping used boats for any length of time, you probably knew that already. The good news is that you can use that as a negotiating tool. On the other hand, if you’re the seller, you stand a better chance of keeping your asking price up if your boat shines.

Either way, a boat does better in the marketplace if its blemishes are fixed.

If the gelcoat scratches aren't too deep, you may be able to eliminate them with a combination of wet-sanding and compounding. 3M makes a variety of products used by the pros.
If the gelcoat scratches aren’t too deep, you may be able to eliminate them with a combination of wet-sanding and compounding. 3M makes a variety of products used by the pros.

If the scratches are deep, you’ll need to know where to get the right gelcoat for your boat. Two of the biggest suppliers in the United States are Spectrum Color in Auburn, Wash., and Mini-Craft in Wildwood, Fla. Each company can help you with color selection and matching. Both companies even have gelcoat colors listed by manufacturer and model year. When you order, the representative will ask you whether you want wax in your gelcoat.

“To make the gelcoat cure, it has to have wax in it, which bleeds to the surface and shuts off the air,” said Mike Miro, owner of Dynamic Fiberglass Boat Repairs in Deltona, Fla. “If you don’t have a wax additive in it, the gelcoat will never cure. It’ll stay gummy.”

To keep this blog entry brief, we’ll deal with deal only with surface scratches. We can delve into deep scratches and those that require spraying on new gelcoat later.

First assess the damage. Scratches that don’t penetrate down into the layers of fiberglass often can be wet-sanded flat and buffed back to a shine with no need for gelcoat at all.

Miro recommends starting out by dry-sanding with 180-grit sandpaper. When you begin to see the scratch disappear, bump up to 320 grit. When 90 percent of the scratch is gone, move up to 400 or 600 grit and begin wet-sanding, working your way up to 1000-grit. When you use 400 grit or higher, be sure to wet sand. Always keep the sandpaper clean with nice fresh water and be cautious not to remove too much gelcoat. It is possible to sand through the color. Believe it or not, 1000-grit has more cutting power than 180. When you sand, wet or dry, be sure you sand in an X pattern, not in a circular motion like would if you were waxing. This keeps the sanded area flat so you don’t end up with “divot” in your hullside or deck.

When the scratch is gone, or at least removed to your satisfaction, it’s time to buff. Miro recommends a three-step process. First he uses 3M Super Duty Rubbing Compound 05954 with a rotary polisher and a wool pad. He then switches to 3M  Perfect It II 05973 Rubbing Compound, and tops that with Perfect It III 05941 Finishing Glaze. Use light pressure on the polisher and let the material do the work. Afterward, use a good synthetic wax to protect the finish.

We’ll address scratches that extend into the fiberglass and resprays in later installments.