Sunday, December 15, 2013

BLOG 60. Easy way to repair gel-coat damage on your canoe

BLOG 60.  Easy Gel-Coat Repair
by Cliff Jacobson

If you own a fiberglass or Kevlar canoe, one thing is certain: one day you’ll hit a rock and chip some gel-coat off your canoe.  If you’ve tried to repair damaged gel-coat “cosmetically perfect”, you know it isn’t easy. The recommended procedure calls for filling the break with color-matched liquid gel coat, then sanding and polishing to blend the repair. This is difficult and frustrating. largely because: catalyzed liquid gel coat is runny and hard to contain.

            Instead, try this 30 minute method:


  •       Epoxy or polyester putty. The rule is to use the same kind of resin for repair that was used to build the boat.  If you don’t know, choose boat-building epoxy which sticks to nearly everything.  Do not use hardware store instant epoxy or any resin that won’t cure rock hard.  If you use epoxy or polyester resin in place of putty you’ll have to thicken it to make a putty that won’t run. The simplest way is to just cut some fiberglass cloth into tiny pieces. Keep adding the chopped glass into the resin until a thick putty consistency results. Better  yet, buy a powdered fiberglass thickener--it's very inexpensive.  I've had good luck with Ad-Tech, West System and Rapid-Cure epoxies.  There are slow and fast-cure formulations.  Fast cure works best for general and gel-coat repairs. Check out the options on line.

This broken seat was repaired with Rapid-Cure epoxy. Noatak River, Alaska

  •       MEKP hardener for polyester resin.  Two-part resin and hardener for epoxy.

  •       popsicle stick for spreading the putty

  •       120  and 400 grit sandpaper

  •       Matching acrylic auto paint (brush or spray)

  •       If you can’t obtain either epoxy or polyester resin, plain old “bondo” will usually work. Bondo is thick and won't run so there's no need to prop the canoe or build a tape well.  Note: gel-coat is purely cosmetic—it provides no structural strength so it probably doesn’t matter much which resin you use, as long as it sticks solidly to your canoe and has reasonable resistance to abrasion.


1.  Use the tip of a knife to remove the shards of damaged gel coat.

2.  Mask the work area, then catalyze the resin and work it into the break to overflowing. If you’re using polyester, add extra MEKP hardener to produce a “hot” mix.  And do wear safety goggles! You don’t want to get resin or hardener in your eyes!. 

3. When the putty is firm (about five minutes), slice off the excess with a knife.  Allow the remainder to cure for another hour then sand it level with progressive grits of sandpaper.  Finish to silky smoothness with wet 400 grit sandpaper.

4.  Spray paint the patch with matching auto acrylic.  When the paint has dried, buff it out with paste wax and pumice.  Or, use a commercial fiberglass boat wax (it contains pumice) which you can get at any marina.  Your repair will be unnoticeable; down time on the canoe is less than two hours.

The stems of these two canoes have been repaired dozens of times. The paint (flat and gloss black) hides the repair and makes it look like a factory option.
Use this procedure if your canoe has a clear (no color) gel coat or a color that is hard to match.

1.  Make the gel-coat repair as suggested then mask a line at approximately 45o to the stem of the boat.

2.  Spray paint the enclosure any color you like.   Observers will think your handiwork is a custom water line. 

Cliff Jacobson