Repairing fiberglass surface.

Craig Ward

Curious about Wooden Canoes
Hi all,
I"ve acquired a cedar strip canoe of 40 something vintage, that is a sought after, locally made canoe. The canoe is great shape in the interior, but the exterior has these whitish areas on it. Is this the varnish or is it in need of a new coat of resin? The worst spot is the one where the cloth has been torn and exposed wood, which has since turned gray. I know I can bleach the wood, but for now I am just wanting to get it in the water to use it this summer. Can I put a patch of cloth over the bare spot, and then new resin? Also, how do I tell whether it is epoxy resin or polyester? I plan to next strip the fiberglass cloth off of it within the next year or so, and apply new cloth and resin.


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Hi Craig,
That's a pretty good looking canoe.
The worn through cloth is a pretty easy fix. You should sand the surrounding area and apply resin, then cloth over the worn area. Then, apply resin to fill the cloth. Try to go slowly to avoid runs. The patch should be cut to fit the worn area. If you want to reinforce it apply another layer of cloth over the patch and overlap onto the adjoining areas. You will need to finish sand to blend your patch in.

The clouded area looks like it is on the surface. Have you tried sanding it to see what happens? Don't go at this with dry paper. Test a small area with a wet sand paper and water. If it's not on the surface then it's clouding from water getting in from inside the boat. If it was stored on it's side that is very possible. If that is the problem, there is no fix.

WRT stripping and re-glassing it, hmm...that could be a nightmare. Even though whoever glassed it was really stingy with resin it still looks like it is pretty well adhered. It's one thing to remove glass from a boat that will get re-canvassed and a totally different deal removing and replacing it on a bare hull. Unless you color the resin or paint it you will not have any way to hide imperfections. I would probably shy away from stripping it and try to live with what you have. You might try giving it a sanding and applying a couple coats of varnish to the hull. That would perk up the appearance and help protect the finish..
I was thinking if I did go to the bother of stripping the fiberglass off eventually, that I would just go straight to canvas on it anyway. It is a Willard Hewey canoe. For this season, and probably the next, I think I will go with what you said and do some patching, filling and sanding, then hit it with the spar varnish. I was just taking a closer look at it and I'm certain the clouding is on the surface, so I'll give it all a light wet sanding and a couple coats of uv spar varnish. Should have access to the good stuff here since they build lobster boats out here! Since it doesn't look like delamination to my eye, I should be able to get quite a few years service out of it before I have to do anything too major. The interior oddly enough is not glassed, just varnished.
I would start by stripping the entire canoe of fiberglass cloth. A canoe that old was glassed with Polyester resin.
Polyester resin is notorious for NOT bonding to wood. It appears to me the white is delaminated fiberglass. Patch it now, especially with epoxy will be a curse later when you want to do it right !

I've removed old Polyester and fiberglass with a heat gun gloves and pliers. Often it helps to score the glass and work it off in strips.

Just my two cents !

How can I tell if it is epoxy or polyester? I know epoxy resins have been used in boat building since the early 70's, and I was told this boat was made in 74. I do not want to get into an involved process for this season, I just want to get it into the water since I have 2 canoes sitting waiting for canvasing.
You can tell because there are lots of small delaminations visible, as well as a couple of big ones. Epoxy resin doesn't do that. I'll add my two cents to Jim's, based on almost 40 years of using, building and sheathing wooden boats and canoes, first with polyester resin and then later with epoxy. Anything you patch at this point is just going to make eventually fixing things properly more difficult. Like it or not, some old used boats simply don't arrive in usable condition. For immediate use, one could probably even make a case for covering the bad spots with duct tape for the time being. At least it's easy to remove. The good news is that the inside appears to be in good shape, might as well strip and canvas the outside before the bad covering screws up the inside as well - which it will eventually do.
The odd thing is that the white areas do appear to be just on top. You can actually see the clear resin below the white attached to the wood. This stuff is stuck like you know what to a bed spread. The one on the bottom has delaminated from the wood for sure. It's going to have to wait till next year for a re canvas job. Thanks guys.
Some of the white stuff is on the surface, but though cosmetically ugly, it's probably a minor issue structurally and could be the result of problems as simple as the varnish that used to be on the surface deteriorating. There is also a lot of exposed glassfiber, indicating that it either didn't get enough filler coats or it was sanded too deeply, but it's all those small delaminated pockets around seams, tack heads, scratches, etc. that are the really serious problems. These are the spots that are prone to water getting in and under the glass, discoloring and weathering the wood and eventually causing rot or expanding. If you want a shining example of how a bad glassing job can eventually destroy a wooden canoe, you've got one. Luckily you got it at a stage where it can probably be fixed and recovered without needing to replace a lot of wood.
If your plan is to canvas it after you remove the glass then you should find it to be a pretty simple job. That's a much better proposition than trying to re-glass it. The suggestion to use a heat gun is spot on. I use a heat gun and a 1 inch putty knife to remove glass. The cloth usually lifts right off.

WRT the patch, the wear is in an area that sees regular abrasion so make your decision about how you will repair by taking into consideration whether or not you want to further damage the wood in that spot. If you are like me the plan to remove the glass will still be on the "to do" list a few years from now and by then you'll be wishing that you had fixed it properly.
Thanks guys. I'm going to fix the bad areas with more fiberglass/resin for now, as well as give it a slight sanding to re-varnish it. Then probably strip it all down next spring to do it in canvas. Fortunately none of the wood has begun to rot, yet. It has been stored in a dry barn for most of it's life, upside own on saw horses. Even the damaged spot on the bottom, the wood is firm and not spongy.
Okay, I did a little experiment today. I wet sanded a bit of the whitish spots and let it dry. I then put a light coat of marine spar varnish over it, and in addition I also put a light coat on a whitish area not sanded. Both dried clear and shiny! I also talked to a fellow that actually worked with the guy that made these local canoes. He is 99.9999% certain that they used epoxy resin on them. I tried sliding a putty knife down inside the hole on the bottom that has had the cloth/resin torn away to see if I could easily lift any of the cloth from the wood. No go, it won't peel off without a whole lot of effort, so it appears to be stuck to the wood well and good. So hopefully within the next couple of weeks I will lightly sand the whole canoe, and patch the hole. I'm thinking of applying a skim coat of epoxy over the whole canoe, then I'll do the marine spar varnish.
Well if it is epoxy, then patch, sand, and varnish. No need to waste a skim coat of epoxy. You will have to sand the canoe twice, and gain nothing with the skim coat.

Quiz the guy about the mixing method. Polyester would have used very small amounts of hardener, and it would have been worse to smell than epoxy.

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When I was talking to the guy about it he said the maker complained about the expense of the resin, and that's why he got a little stingy with it. He also said he wasn't impressed with other canoes where the fiberglass peeled off a few years down the road. No sign of the white haze returning, so I think I'll just do as you said and patch, then hit it with the varnish and go canoeing. There really is no place on this canoe where the cloth is pulling away from the wood, other than where it was damaged on the very bottom.
I'd still wager that it's polyester resin. Epoxy just doesn't generally do the type of small delams and damage visible in the photos, but they're extremely common with polyester. Epoxy also has a pretty limited UV lifespan, and by the time the protective coatings get that bad, the resin under them is starting to crumble. You could tell by the smell of the sanding dust, even after all these years if you know what styrene smells like.
But if it was delaminations, the varnish shouldn't make them disappear though, and they are gone once I put varnish on.
Look at your first posted photo, on the left side of the picture and the bottom half of the hull with all those small, yellowish discolored spots at the plank seams, tack heads, etc. Are you saying those all go away when you put some varnish on?
Those spots I don't know about yet, I haven't put any varnish on those. I doubt if they will go away, but if they are delamination spots, they are sure still stuck to the wood good and tight. I see what you mean though. Given how well the fiberglass is still attached, I will go ahead with my original plan of fixing the tears/breaks, then varnish it all over. Next season I hope to have my Bob's Special canvased and in working order, so then I can work on this canoe. If the fiberglass comes off nicely, I'll probably cover it in fiberglass again, just because that is what the builder did with them and they are sought after in Nova Scotia. If it makes a mess of the wood, I'll canvas it.