Gelcoat Repairs Revisited

Posted by Darrell Nicholson at 03:09PM - Comments: (6)

A Dremel tool smooths a gouge in one of Practical Sailor's former work boats, a Parker 23, before repair.

Eventually every owner of a fiberglass boat will have to deal with gelcoat cracks and chips. Fixing these minor blemishes are well within reach of the competent do-it-yourselfer, but to make a nearly invisible repair takes a bit of practice. Achieving the same level of gelcoat gloss, adhesion, and color of the original hull or deck is a kind of black art, and it is a field full of pretenders. You could run a weekend movie marathon featuring all of the YouTube DIY videos offering bad advice on gelcoat repairs.

Many boat owners simply throw up their hands and opt to paint the hull with a one-part or two-part paint, a project we’ve examined in great detail—from prep work to paint selection to refinishing tips—in our multi-part series on linear polyurethane (LPU) marine paints. If you have deeper gouges to repair before either project—painting or gelcoat— then our tips on using pre-thickened epoxy fillers will be helpful. For a more detailed look at choosing and using these products, subscribers can also review our test reports on pre-thickened epoxy fillers, and mix-it-yourself fillers and fairing compounds.

In an upcoming series of articles we’ll be looking at the art of gelcoat repairs—everything from color-matching to filling to spraying. We’ll also be looking at the various gelcoat repair products.

I recently got the chance to speak with Paul Lacharite of Mini-craft of Florida on the topic of gelcoat repair. Lacharite has been manufacturing gelcoat since 1976, and in 1980, he became interested in mastering the art of matching colors, helping to develop a system that enables repairers to quickly match the original color of almost every boat that ever hit the U.S. market. He now runs a series of professional workshops from October to March every year at the Mini-craft facility in Wildwood, Fla.

Over the years, Mini-craft has assembled an inventory of sample panels of the gelcoats used by most major watercraft built in America. Using these panels and some basic information from the boat’s manufacturer, they can match the gelcoat of virtually any boat over the phone. Since gelcoat—especially colored gelcoat—weathers over the years, achieving an exact match often still requires some onsite color-matching skill, but if a “6-foot finish” (a repair or refinish job that is undetectable from more than 6 feet away) is all you want, Mini-craft’s in-house blend will be a pretty close match.

Mini-craft’s products and tools are geared to the professional, but they sell directly to the consumer as well. Unlike other gelcoat suppliers, they don’t just can and label gelcoat made elsewhere, they make it themselves at their Wildwood facility. They offer different grades of gelcoat, and all the equipment you would need to carry out repairs. However, given the challenges of many gelcoat projects, Lacharite reluctantly sells to the average Joe.

“People don’t want to follow instructions ,” he explained. “It’s human nature. And then, when something goes wrong, it’s never their fault. It’s the product.”

One of the most common errors Lacharite sees happens when a do-it-yourselfer or pro wants to spray apply gelcoat to a small area after a repair. For small repairs like this, we use a Preval sprayer, a process I outlined in my previous blog post on gelcoat repair. As it turned out, my own advice in the blog post, based on instruction from a local boatbuilder who’d made hundreds of such repairs, was a victim to this cycle of misinformation. (It has since been amended.)

“People are always advising to use acetone to thin the gelcoat,” Lacharite said. “This is wrong for many reasons.” In summary, he explained, if you use acetone to thin the gelcoat for spraying, you will shorten its life, and get a duller, rougher finish. Styrene is no better, he said; it will cause the gelcoat to yellow. What you want is a properly formulated reducer, something that Mini-craft supplies with its repair kit.

Until recently, Mini-Craft used to sell a handy aerosol gelcoat repair kit, but Lacharite said it became too expensive to produce. The company now offers a similar kit using the Preval sprayer, but its geared toward bigger projects with multiple repairs, so the price is pretty high (starting at $275).

Look for our update on gelcoat repair early next year, and if you have some repair products or techniques to share, comment below or drop me a line at

Comments (6)

Let me be perfectly clear, I am not looking for perfection. Meaning, mine is a well cared for 1980 Hunter Cherubini 37. The gelcoat is dinged in spots but nothng even approaching structural. It has also yellowed a lot, especially along the nonskid walkways. After observing this for a couple of years we've owned it I had a inspiration! I took one of my lazerette hatches OFF of the boat and took it in to my local Sherman Williams paint store. They were able to copy the exact gelcoat vanilla color into a quart of Exterior, satin finish all weather latex!
After lightly sanding and wiping off the surface I carefully brushed on the new paint. Even where I just spot-painted with it, you cannot see the difference from the gelcoat to the painted area.
NEXT: my wife said that she couldn't get the paint to cover the nicks.Solution: a primer called KILLS goes on first and the paint now covers and hides the black marks. Even a month since we did this it still looks fresh and 100% better than before.

Posted by: JHoward | September 14, 2017 2:01 PM    Report this comment

Boatworks today-via u-tube--has really good step by step instructions from a professional boat repair shop--Im completely rebuilding a 28 foot Lancer and they have proved invaluable. I still seek factory advice (interlux has an especially detailed customer service and tech question facility.

Posted by: RON H | August 21, 2014 11:16 PM    Report this comment

How about repairing mildly cracked (balsam cored) decking containing a non-skid pattern. No water damage is apparent.

Posted by: Ray M | July 23, 2014 11:46 AM    Report this comment

Absolutely timely. I just bought a 1988 MacGregor 26D and have had the mis-fortune to have docked it to the outside dock this 4th of July weekend. When I came Back on the 5th of July all the boats on the dock had their fenders lying on the dock rather than in-between the boat and the dock. I found our it because of all the boats going past on the river channel never slowed down as they were passing our marina. so their wakes were so high that they caused the fenders to rise out of the water and land on the dock. needless to say we all have gel-coat repairs to do.
What do you recommend to thin the gel-coat so it can be used with the PREVAL Sprayer?

Posted by: medicbrent | July 12, 2014 8:28 PM    Report this comment

Great, it's amazing how many different whites you have to mix to get close to matching the original weathered gelcoat, and that's only the white. Anything to make it easier with less guess work.

Posted by: Groover M | July 2, 2014 11:26 PM    Report this comment

Very timely. Have a project to do on my 1982 Cape Dory 25D. I think that the "6-foot finish" will be very acceptable. Looking forward to the series.

Posted by: DOUGLAS H | July 2, 2014 3:33 PM    Report this comment

New to Practical Sailor?
Register for Free!

Already Registered?
Log In