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Looking for advice on repairing 1970's old town fiberglass canoe

Jul 1, 2022
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HI there! My name is Logan and I am new to this site, and fiberglass canoe repair.

I would like to fix up my dad's Old Town canoe. This is a sentimental project, and I don't intend to hit any big rapids or rocks, if I can get it fixed up. He purchased it new in the late 70's (unsure exactly when). About 20 years ago he covered the whole bottom with a layer of glass and resin because there were several small cracks and soft spots. Unfortunately the canoe spent several years in the sun recently and this bottom layer turned yellow and brittle.

I removed the brittle layer with a grinder and discovered several cracks. My plan was to remove the busted glass around the cracks, patch up, and take my son fishing. But when I started grinding the first crack I discovered quite a bit more damage than I expected. The layers had delaminated so a small pocket had formed and there was a lot of discolored (brown) fiberglass in between. I kept grinding to get rid of all this, but the whole kept getting bigger and bigger!

If I keep it up I"m going to meet up with the next crack in the middle of the boat. My concern is I'll end up replacing the whole bottom of the boat (don't really want to do that). So my big question is... is this a lost cause? Should I just patch what I've done, and hang it up for retirement? I"ve attached a few pictures to help show what I'm talking about. Any help will be greatly appreciated! Thanks!


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Welcome to site membership, Logan! I'm not one of the repair experts, but do feel free to ask any questions and to post messages, photos and videos in our many canoe-related forums. Please consider adding your location to your profile, so it shows up under your avatar in your posts.

Hopefully, others will chime in soon with some opinions on your project.
What's it like on the inside of the hull in the area where the fiberglass is discolored? If you can knock on it and it's fairly solid, maybe you can move on from the grinding and just patch. Not every crown needs a root canal. Is the rotten material structural fiberglass or part of a foam core?
hey goonstroke, the rotten material is part of the core. the inside layer of fiberglass is still solid. I'm thinking water got in from the previous bad patch job and a bunch of the core delaminated and rotted?
I think if it were me I'd be tempted to stabilize the edge of the core and start patching. In your third picture the fiberglass on the outside of the core looks very solid. If the hull is still stiff enough (i.e., it doesn't oil can easily) then maybe the boat is strong enough with essentially filler in the core. If it's soft and makes disturbing bag-of-pasta sounds when you press on it then maybe not.

Does anyone know what Old Town would have used in there?

BWT the year of manufacture is normally two digits at the end of the serial number.
I have no idea what that brown, crumbly-looking stuff is but I suspect it was some rather inexpensive material, the sole purpose of which was to give the hull some additional thickness, and thus stiffness.

I would measure its approximate thickness and replace it with new core material. A core material I have used with good results is Coremat, which comes in different thicknesses. Coremat doesn't add a lot of strength and it soaks up a good bit of resin, but it is pretty easy to work with and not terribly expensive compared to some other core materials.

You are then going to want to cover that with at least a couple of layers of fiberglass cloth. You could, of course, fill in the entire void with as many layers of fiberglass fabric as needed but that would require a lot more time, resin, and expense and the repair would be a good deal heavier.