How To Repair Rough Fiberglass

How to Repair Fiberglass

Updated: May 22, 2022

Fix boats, personal watercraft, even truck toppers with these fiberglass repair tips. Do it yourself and relieve thousands.

Fiberglass-boat-repair-fiberglass-repair Family Handyman

A repair pro shows you lot how to make invisible fixes for scuffs, dents and scratches in fiberglass boats and other fiberglass items. You'll relieve a ton of money if y'all're patient and use the proper tools.

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Fiberglass Repair Overview: Cost, savings and repair strategy

Even the best boat captain has had a docking turn into a scuff-and-fleck event. Simply y'all don't have to pay astronomical marina fees to become your boat fixed. You lot can practice it yourself with advice from expert fiberglass gunkhole repair specialist Chris Hassis. He'southward fixed boo-boos on fiberglass personal watercraft, snowmobiles and pickup toppers, and even luxury yachts. Y'all'll need the right tools and materials—and lots of patience. But he'll show you how to salve a ton of money on boat fiberglass repair and brand your boat expect like new with some fiberglass gunkhole repair tips. Nosotros were astounded at this refurbished boat's rebirth. The boat now looks equally as good as it did in the exhibit afterward some fiberglass repair.

Most hired-out repairs of whatever blazon are roughly 50 pct labor and l percentage materials. Not so with this prepare—hull repairs are all nigh labor. The repairs on this boat would cost roughly $iii,000 at a shop. But the materials only cost near $250 and the buffer about $150! Then roll up your sleeves. Your fiberglass boat repair might not be perfect, but your boat will look unbelievably better than it did before. But don't endeavour to rush or skimp on the materials. And know that this task is much bigger than it looks.

All fiberglass boats accept a thick structural cadre of fiberglass strands impregnated with polyester resin. But the function you really see is the gel coat. That'south the sparse layer of pigmented resin that gives the boat its sheen and color. Virtually light scratches are in the gel glaze layer. They can be sanded out and the surface area built back up with new gel glaze. Merely if they penetrate the core, they need to be filled. You tin tell that the scratch is into the core if you come across fiberglass fibers (Photo 2).

Remove graphics

Photo 1: Remove quondam numbers and pinstripes to begin fiberglass repair

Ready the heat gun to a low setting and pare off the old decals and numbers. Apply adhesive remover to get rid of any remainder.

No boat spiff-up is consummate without new license numbers, transom names and pinstripes. Just practise an online search for "gunkhole graphics" and you'll detect thousands of options to choose from. Detect stripes by searching for "boat pinstripes." Remove the quondam ones by warming them with a heat gun (Photo 1). 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.

Fix gouges: Prep

Photo 2: Ready deep gouges

Cut a U-shaped groove into the gouge with a high-speed dice grinder or rotary tool and a burr nose bit. Taper the edges of the gouge to eliminate sharp edges in the old gel glaze.

Grind out gouged areas with a V-shaped grinder flake (Champion SF1; from heavydutystore.com; Photo 2). Sand out the light scratches, starting with 80-grit, to 150-grit, and ending with 240-grit.

Ready gouges: Fill and smooth

Photo 3: Prepare the filler

Stir in enough chop to get the mixture to the consistency of peanut butter. So add together hardener (follow the manufacturer's ratio) and stir, stir, stir.

Photo 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 most 1/32 in. above the surface. Clean up whatsoever goofs with acetone.

Photo five: Sand the patch

Knock downwardly the backlog putty with 80-dust sandpaper and a rubber sanding block. Then switch to 240-grit.

To fix gouges and deep scratches, you'll demand "chop" (powdered fiberglass) filler, gel glaze and gel glaze reducer. Jot downward your boat'south model and serial numbers and contact the manufacturer to lodge gel glaze (about $100 per qt.) to lucifer your boat's color. It may not exist an exact lucifer, but it'll be a lot closer than mixing colors from scratch. And then society some gel coat reducer (Patch-Assistance is 1 make; nearly $49 per qt. from minicraft.com or spectrumcolor.com) to sparse the mixture plenty to get through the spray gun. For gouge repair, you'll mix chop filler (Chris uses Cab-O-Sil from epoxy5050.com) with the gel coat to create a thick paste. Then pick up newspaper cups, stir sticks, acetone (for cleanup) and rags. You'll as well demand a disposable spray gun (Preval is one brand; about $7 online or at paint and fine art supply stores). To finish the job, you lot'll need a professional-blazon buffer. The variable-speed feature is important, and so is the high power of a professional buffer. So don't skimp on one or think yous tin can get by with a $29 wax polisher. Utilize a wool buffing pad (such as a Dewalt DW4988 pad, bachelor through our amalgamation with amazon.com or westmarine.com), and buffing chemical compound (3M Imperial Compound and Finishing Material, which is what Chris uses, available through our affiliation with amazon.com or westmarine.com).

Mixing gel coat is a messy and stinky process—so wear chemical-resistant gloves, safety goggles and a respirator. Start with a modest amount of gel coat and stir in the chop and hardener to make a putty that's the consistency of peanut butter (Photo three). Once you add the hardener, you've only got a 10- to 20-minute "open up" time, so mix small batches and work on 1 gouge at a fourth dimension. Thorough mixing is critical to proper curing. Spend a full minute stirring. If you don't, you'll end up with patches of glutinous resin that can accept days to harden.

Overfill gouges and so the filler mounds slightly. Yous'll sand it flush after it cures. Curing tin take one to two hours—depending on humidity levels. So test it past touch. If it's glutinous, it'south not fully cured. Once information technology'southward fully hardened, sand it with 80-dust sandpaper (Photo 5).

Color-Matching Gel Coats

Sometimes y'all can't get your hands on factory gel coat (your boat is too former or the manufacturer is out of business organisation). And then you have two options. You tin can club an off-the-shelf color that'southward close to yours and decide that "shut enough is skilful enough." The other option is to custom mix, but exist aware that this is no easy job. Buy a colour chip chart for off-the-shelf colors (from a local marine supplier, or become the No. 01900 color chart from rayplex.com for near $12). Mix your own color with a kit (No. 33114; about $35) from rayplex.com.

Fix gouges: Use the finish

Photo half-dozen: Mix new gel glaze

Add the hardener later you've mixed in the reducer. Follow the manufacturer's recommended ratio of hardener to gel coat.

Photo vii: Spray on the final glaze

Pulse the sprayer to go short bursts of gel glaze. Plume the spray along the edges to reduce sanding.

Photo 7A: Close-up of sprayer

A pre-charged sprayer applies the final glaze more than smoothly than brushing, but you still have to sand it out.

Now you're ready to mix a fresh batch of gel coat (without the chop) and spray the scratched and patched areas (Photos six and vii). Chris recommends using a disposable spray gun and paper cups. Unthinned gel glaze won't become through the sprayer. Add the recommended amount of reducer (read label directions) and hardener and mix the ingredients. Spray the patched areas with short bursts. Spraying gel coat isn't like spraying paint. It splatters on and has to exist sanded and buffed to go to a smooth gloss. Then don't be disappointed that the stop isn't paint-like right away during your fiberglass boat repair.

Terminal-sand, buff and wax

Photograph 8: Buff to a great shine

Take a seat and heft the buffer into position. First slowly and buff minor sections at a time.

Photo 8A: Shut-up of buffing compound

Buffing compound produces a silky smooth stop.

Photo ix: Utilize new decals

Position the new boat numbers and tape the sail in place. Then lift the sheet up, remove the capitalist and press each number individually. Don't endeavour to apply them all at once—they'll wrinkle.

Look for the gel coat to cure. Sand the repairs with 600-dust then 800-dust sandpaper. For the perfect finish, sand with 1,200-dust wet/ dry paper then buff (Photograph viii). Apply buffing compound direct to the pad. Piece of work on a ii x 2-ft. area and employ light to medium pressure at a adequately low speed. Reduce force per unit area as the compound starts to dry. Wipe off the haze as yous go. Apply the graphics and so wax.

Club of Events for Fiberglass Boat Repair

Wash and rinse the boat. That volition prove you all the dings that demand fixing. Mark them with masking tape and so yous won't forget any.

If you're replacing pinstripes, license decals or other graphics, remove them adjacent.

Make full whatsoever deep gouges and spend your time sanding out scratches while the filler sets up.

Apply gel coat to the filled gouges and cease to the scratches and then final-sand the filled gouges.

Buff all the repaired areas and so the remainder of the boat.

Apply any graphics to finish up.

Required Tools for this Boat Fiberglass Repair Project

Take the necessary tools for this DIY boat fiberglass repair project lined up earlier y'all start—you'll salve time and frustration.

You'll also demand a variable speed buffer, wool buffing pad, chemical-resistant gloves, respirator and a burr-nose grinder bit.

Required Materials for this Boat Fiberglass Repair Projection

Avert last-minute shopping trips by having all your materials prepare ahead of time. Here'southward a list.

Originally Published: November 26, 2022