Epoxy Fiberglass Question

The Santa Fe Surf Club in New Mexico has a 6-man malia canoe that needs some TLC. In particular, the wooden gunnels need re-glassed. They have been sanded down to bear wood and we are poised to buy a product to apply. Problem is, none of us has much experience in fiberglass work! One of our team members suggested we look for an epoxy product that has the glass fibers suspended in it. Any advice out there for some land-locked, desperate and displaced outrigger canoe paddlers?

Submitted by sbeuler on Tue, 06/10/2014 - 11:22am

Your best bet would be to try and contact an autobody shop to see if they have anyone who knows how to work with fiberglass and resins (whether it be polyester or epoxy based) or even to see if they can help in doing the job for your club.

Our club got a (retired) guy that worked in autobody repair and has done a bunch of work on our practice canoes to get them back on the water.

#1 Tue, 06/10/2014 - 10:36pm

It's not really that hard to do. You can obtain materials from places like this: http://www.fiberglasssupply.com/
You'll basically need glass cloth (probably 3 - 4 oz cloth), a clear slow-setting epoxy, and sandpaper. Are you needing to re-gelcoat the boat as well? At any rate, here is a guideline from Current Designs for fiberglass/Kevlar repair:

Fiberglass/Kevlar Repair
For your Current Designs Kayak

? Rough up the inside surface of the affected area using a power grinder. Feather out the edge slightly more than half the diameter of the area to be patched.
? Clean the surface and remove all paint or foreign substances with acetone.
? Cut out one piece of fiberglass fabric and matt to the shape of the damaged area and a second, larger piece of fabric and matt 1-1/2 the diameter of the damaged area. (Matt is the fiberglass patch that looks like particle board or pressed fiberglass.)
? Thoroughly mix an ample amount of resin (approximately 1 pint/sq. ft.) and catalyst (1/2 tsp./pt.). Lightly brush the area to be repaired with the resin. On a piece of cardboard, lay the cloth down and completely wet with resin. Lay the matt on top of the cloth and wet the matt win the same manner. Lift the fiberglass cloth and matt off of the cardboard and apply it to the damaged area with the matt against the boat.
? Use a small roller or squeegee to force out all air bubbles and remove the excess resin with a dry brush. Clean the tools with acetone. Allow the area to completely cure. Build this laminate up to the same thickness or greater than the thickness of the original laminate.
? Using 80 grit sandpaper on a sanding block, smooth and blend the patch in to the surrounding surface.
? Repair the outside, or gel coat surface, as described in the gel coat section of this manual.
? Always use rubber gloves and safety glasses when handling resins, catalysts, and acetone.

Huki also has some very good information on fiberglass/gelcoat repair:

Repairing small cracks, small holes, small dents and dings
The repairs are done exactly the same as surfboard repairs. The tools are the same and safety glasses mask and gloves must be worn.
If repairing a canoe that is older than 6 months, it’s best to use Epoxy resin for patching any punctures and use 3.7 oz fiberglass cloth in the patch repairs. If repairing a canoe that is less than 6 months old, try to find vinylester resin to use in the repair if possible, otherwise use epoxy resin. Epoxy makes fine repairs in any case.
If you have a crack through the gelcoat, you will need to grind through the gelcoat to expose the fiber material underneath, using 36 or 50 grit sand paper. Sand only about a quarter inch outward from any crack or hole to expose the fiber structural material. DO NOT sand into the fiber structure. You simply want to expose the fiber material. If you have only a ding or tiny dent without any crack or hole, then sand within the dented area with 220 grit sand paper and skip onto the next step.
Sand or “scuff” the area immediately around the ground out area or around the ding lightly with 220 grit so as to remove the glossy shine from the surface of the gelcoat, but not to remove all the gelcoat and don’t dare to sand away so much gelcoat so as to make it thinner. This scuffed area should radiate out from the heavily ground out area by about 1.5 inches and will serve as a gripping surface for your finish gelcoat when you spray or brush it on for feather effect.
If you’re bridging over a crack or hole in the fiber structure, Cut 3.7oz Fiberglass patches that are larger than the ground out area by about half an inch in all directions. (Use fiberglass because it will flex without cracking in this high stress area). If you’re simply filling a dent or ding with fiberglass, the repair is the same as with covering a crack or hole. If the ding or crack is shallow enough that you could fill it with gelcoat, skip this laminating process.
Work with Glass or Carbon cloth that is less than 5.7 oz, 3-4 oz being optimum. Laminate your cloth in multiple layers over the ground out area and wet out only to the edge of where the gelcoat grindings begin. Laminate enough layers of cloth so that the surface rises above the surrounding faired surface so you can fair it down to match the surrounding surface level. If your patches of cloth are properly larger than the ground out area, just wet the patch to the edge of where the gelcoat grindings begin, leave the outer edges of the cloth dry. You DO NOT have to wet out the entire patch of cloth.
Once your patch hardens fully, sand it down starting with 100 grit. The dry pieces of cloth will fly off in the first few swipes of the paper, leaving your actual patch to be faired down almost fair with the surrounding surfaces. Then go to 220 grit and fair the patch down to match the surrounding gelcoat. Don’t worry about pin holes and pits yet. Wipe off the faired area with an acetone rag. Spray with gelcoat thinned with patch reducer or with acetone, catalyze at 2% and mix in 2-4% liquid wax. Don’t spray beyond your 220 scratches because the gelcoat won’t stick. Spray on thick but don’t get runs. Allow the gelcoat to harden fully.
Fair down the gelcoat starting with 220 wet sand paper for about thirty swipes.
Go to 400 grit wet for about 25 swipes.
Go to 800 grit wet for about 20 swipes.
Go to 1200 grit for about 18 swipes.
Go to 2000 grit for about 15 swipes.
Rub with heavy duty rubbing compound for about 30-40 swipes.
Rub with polishing compound for about 100 swipes.

#2 Thu, 06/12/2014 - 7:55am

I've made simple repairs to fiberglass boats using two or three layers of 3.7 oz cloth, wetted in a clear slow-setting epoxy, and laid down on a clean, sanded surface. By covering the repair area with a clear plastic packing tape or similar it will help hold it in place and leave a fairly smooth finish when you remove it.

#3 Thu, 06/12/2014 - 8:00am


Better yet, move back west and get out of NM! The mighty Santa Fe river is low. Hahahaha


#4 Thu, 06/12/2014 - 11:02am

Thanks for your informative, educational and funny (MOE) comments everyone. I'm going to print them off and order some supplies. The work party to finish the prep on our canoe is in a couple of weeks. I'll try to post some photos of our restoration, if you're interested! Mahalo from all of us with the Santa Fe Surf Club!

#5 Fri, 06/13/2014 - 11:07am

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