I’m recently new to paddling and purchased my first canoe used. The previous owner said that this canoe was a project of his that he repaired and was now selling. It is made of Royalex.
The keel and stern had a piece of flextape on it to protect and cover the main repairs that he had done. When I got it home, I saw that the flextape was peeling off. I removed most of it and saw that there was a silicone patch job filling in most of the crack in the hull (both keel and stern).
I purchased a Kevlar patch kit and was intending on bonding it to the hull with GFlex 650 epoxy. I first tested to see if the epoxy would bond to the silicone and unfortunately, it won’t.
What would you guys recommend that my course of action should be? Do I need to pick out all of the silicone to do a proper repair job? My intention is to fix it correctly, because I might keep this canoe for a while.
Yes, one way or another you will need to get rid of all of the silicone.
Unthickened G Flex epoxy as in the 650 kits is what you want for bonding fabric to Royalex. I would get some colloidal silica powder (cab-o-sil) to thicken the epoxy moderately and use that mixture to fill in the voids and rebuild the missing ABS before laying on your cloth.
I have repaired quite a few canoes. Unfortunately, a lousy repair job previously done usually makes a proper repair job at least twice as hard.
@pblanc said:
Yes, one way or another you will need to get rid of all of the silicone.
Unthickened G Flex epoxy as in the 650 kits is what you want for bonding fabric to Royalex. I would get some colloidal silica powder (cab-o-sil) to thicken the epoxy moderately and use that mixture to fill in the voids and rebuild the missing ABS before laying on your cloth.
I have repaired quite a few canoes. Unfortunately, a lousy repair job previously done usually makes a proper repair job at least twice as hard.
Yes to GFlex, yes to the patch…yes to silicon being an absolute no for any repairs on canoes and the problems related. You’ll need to dig it all out.
I would add that you can/should heat the area of the repair before doing it. I use my hand held propane torch (very carefully) before applying a stem patch.
The instructions that come with G Flex are quite specific as to the procedure for flame oxidation.
In West Systems tests, pre-treatment with flame oxidation did enhance the bond strength of G Flex epoxy to ABS, but in my experience, a good and durable bond can be achieved without flame oxidation. With polyethylene however, flame oxidation pre-treatment is a must. The bond will be nearly worthless without it.
I would go ahead and pre-treat solid ABS layers before bonding with G Flex when possible. When the foam core is exposed however, extreme caution with a propane torch is required. The foam core can deform or melt in the blink of an eye and sometimes discretion becomes the better part of valor.
Exposed foam core has many little interstices that greatly increase the bonding surface for the epoxy and the many little crevices also gives the resin a good “bite” into the foam core. In most cases, I have not tried to flame oxidize the exposed foam core of ABS before bonding G Flex to it, and I have had no problems with that approach.
You guys are amazing. Thank you so much for all of your help. This started as an intimidating project, but in my research I think it’s totally within my skill level.
It seems to have worked really well loosening the silicone and getting rid of the flex tape. It’s mostly clean now. In the coming days, I hope to finish this project and get paddling!
