Fix boats, personal watercraft and truck toppers.
Time A full day
ComplexityIntermediate
Cost$200 to $350
Introduction
A pro shows you how to make invisible fixes for scuffs, dents and scratches in fiberglass boats and other items. You'll save a ton of money if you're patient and use the proper tools.
Even the best boat captain has had a docking turn into a scuff-and-chip event. But you don’t have to pay astronomical marina fees to get your boat fixed. You can do it yourself with advice from expert fiberglass boat repair specialist Chris Hassis. He’s fixed boo-boos on fiberglass personal watercraft, snowmobiles and pickup toppers, and even luxury yachts.
You’ll need the right tools and materials—and lots of patience. But he’ll show you how to save a ton of money on fiberglass repair and make your old boat look like new with some fiberglass boat repair tips. We were astounded at this refurbished boat’s rebirth. After some fiberglass repair, the boat now looks every bit as good as it did in the showroom.
Most hired-out repairs of any type are roughly 50 percent labor and 50 percent materials. Not so with this fix—hull repairs are all about labor. The repairs on this boat would cost thousands at a shop. But the materials and buffer should only cost a few hundred. Your fiberglass boat repair might not be perfect, but your boat will look unbelievably better than it did before. Just don’t try to rush or skimp on the materials. And know that this job is much bigger than it looks.
All fiberglass boats have a thick structural core of fiberglass strands impregnated with polyester resin. But the part you see is the gel coat. That’s the thin layer of pigmented resin that gives the boat its sheen and color.
Fixing light scratches
Most light scratches are in the gel coat layer. They can be sanded out and the area built back up with new gel coat. But if they penetrate the core, they need to be filled. You can tell that the scratch is into the core if you see fiberglass fibers.
Filling deep gouges
To fix gouges and deep scratches, you’ll need “chop” (powdered fiberglass) filler, gel coat and gel coat reducer. Jot down your boat’s model and serial numbers and contact the manufacturer to order a gel coat to match your boat’s color. It may not be an exact match, but it’ll be a lot closer than mixing colors from scratch.
Then, order some gel coat reducer (Patch-Aid is one brand) to thin the mixture enough to go through the spray gun. For gouge repair, you’ll mix chop filler with the gel coat to create a thick paste. Then, pick up paper cups, stir sticks, acetone (for cleanup) and rags. You’ll also need a disposable spray gun.
To finish the job, you’ll need a professional-type buffer. The variable-speed feature and the high power of a professional buffer are important, so don’t skimp on one or think you can get by with a cheap wax polisher. Use a wool buffing pad and buffing compound.
Tools Required
- Heat gun
- Rotary tool
- Safety glasses
- Sanding block
Materials Required
- Acetone
- Buffing compound
- Disposable spray gun
- Gel coat
- Gel coat reducer
- Powdered fiberglass filler
- Sandpaper
- Wax
Project step-by-step (9)
Step 1
Remove old numbers and pinstripes to begin fiberglass repair
Remove the old ones by warming them with a heat gun. But be careful—if you overheat the surface, you can burn the gel coat. If yours are painted on, sand them off with 1200-grit sandpaper.
Step 2
Prepare deep gouges
Cut a U-shaped groove into the gouge with a high-speed die grinder or rotary tool and a burr nose bit. Taper the edges of the gouge to eliminate sharp edges in the old gel coat.
Sand out the light scratches, starting with 80-grit, to 150-grit, and ending with 240-grit.
Step 3
Prepare the filler
Mixing gel coat is a messy and stinky process—so wear chemical-resistant gloves, safety goggles and a respirator. Start with a small amount of gel coat and stir in the chop and hardener to make a putty that’s the consistency of peanut butter. Once you add the hardener, you’ve only got a 10- to 20-minute “open” time, so mix small batches and work on one gouge at a time.
Thorough mixing is critical to proper curing. Spend a full minute stirring. If you don’t, you’ll end up with patches of sticky resin that can take days to harden.
Step 4
Fill in the gouge
Scoop the gel coat putty into the gouge. Then, press it into the fibers with a craft stick. Add more putty until you’re about 1/32 in. above the surface. Clean up any goofs with acetone.
Step 5
Sand the patch
Knock down the excess putty with 80-grit sandpaper and a rubber sanding block. Then switch to 240-grit.
Step 6
Mix new gel coat
Now, you’re ready to mix a fresh batch of gel coat (without the chop) and spray the scratched and patched areas. Add the hardener after you’ve mixed in the reducer. Follow the manufacturer’s recommended ratio of hardener to gel coat.
Chris recommends using paper cups to mix the new gel coat and a disposable spray gun to apply it.
Step 7
Spray on the final coat
Spray the patched areas with short bursts. Feather the spray along the edges to reduce sanding.
Spraying gel coat isn’t like spraying paint. It splatters on and has to be sanded and buffed to get to a smooth gloss. So don’t be disappointed that the finish isn’t paint-like right away during your fiberglass boat repair.
Step 8
Buff to a great shine
Wait for the gel coat to cure. Sand the repairs with 600-grit and then 800-grit sandpaper. For the perfect finish, sand with 1,200-grit wet/ dry paper, then buff.
Apply buffing compound directly to the pad on your buffer. Work on a 2 x 2-ft. area and use light to medium pressure at a fairly low speed. Reduce pressure as the compound starts to dry. Wipe off the haze as you go.
Step 9
Apply new decals
Position the new boat numbers and tape the sheet in place. Then lift the sheet up, remove the backer and press each number individually. Don’t try to apply them all at once—they’ll wrinkle.
Once that’s done, wax the boat
