Anatomy of a Kevlar Canoe Repair

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Anatomy of a Kevlar Canoe Repair

Greetings from the Northwoods!  With the rental fleet refinishing behind us, the winter canoe repair program is in full swing!  I thought it would be fun to take you through a recent repair I made, so that you can understand the process and hopefully decide we are the place to bring a damaged canoe.

Here you see a photo of the inside (below, right) and outside (below, left) of a canoe with a cut all the way through the hull. This damage went into the gunwale, which adds an extra challenge to the repair process. No worries, though, we’re prepared for anything!

The first step was to drill rivets and lift the gunwale in order to allow us the necessary surface area around the damage, then acetone that area and sand it – resin will not bond well to a surface unless it is ruffed up first.  This repair also required that I brace the hull of the canoe, as the surface was warped by the damage to the gunwale, to provide an even surface for the patches.

Next, I resined the entire area, applied the patch, soaked the patch in resin, and applied a release cloth.  The fiberglass patch will stay with the boat for the rest of its life, but the release cloth will be removed once the resin has completely cured.  This can be a tricky process when the damage is through the entire hull, as there are many loose fibers and spaces where the canoe does not want to go back to its original form.  We have ways to overcome these challenges, with lots of surface preparation, but it’s not easy. 

Patch and release cloth applied.

Above is the final product.  The photo on the left shows the patch and surrounding resined area after removing the release cloth.  Because there was so much distortion on the surface, you can see a sliver of area that is discolored.  This is where the patch did not contact the surface, and so I had to sand it down slightly and drip some resin into the porous area in order to seal and reinforce the crack (above, on the right).

Patching the inside of the canoe was trickier because the surface was more distorted than the outside and there were more exposed Kevlar fibers (pictured above, on the right).  In order to create a surface even enough to patch I use a material called Cabosil (nasty stuff, shown above), which is essentially powdered fiberglass, mixed with resin in order to create a paste.  We apply this paste to an uneven surface to fill in and even out, which is also helpful when fixing divots to a foam core.  This is tricky because once the resin and hardener are mixed, the patch needs to go on in short order (apply paste, smooth surface, resin remaining surface for patch, apply patch, apply release cloth.  So, prior to applying this paste I sanded and acetoned the area around the patch, repeating the process from the outside patch.  Below you will see this fiberglass patch and release cloth applied to the damaged area.  Without the Cabosil paste there would be large spots where the patch did not adhere, which would require more sanding, more resin, and possibly a second patch.

And now the final product, inside and out, after replacing and riveting the gunwales, shown below.  This customer did not want to buy new gunwales, given the age of the canoe, and the nature of the bent gunwale did not allow us to straighten it, but it will not threaten the integrity of the hull or hamper the performance of the canoe in any way.  This canoe is ready for many more adventures.

Click on the link below to have a look at repair pricing and guidelines:

Thanks for following my repair!

— Canoe Guy Tyler

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