From: Reed Larson
I live in northern Minnesota and recently purchased my first canoe ... a used 18' cedar strip. I think it is about 12 years old. It is in very good condition and after owning it for only two days, I can't believe I've never considered a wooden canoe before. There are several fine cracks and a few chips out of the finish on the bottom of the boat. I can chip off small but fairly thick pieces which I believe to be a thick coat of varnish ... it does not appear to me that the underlying epoxy has loosened or separated from the wood, but there may be a few isolated locations where water has reached the wood and left a few darkened spots.
My question is what is the best way to put a nice finish back on the boat. Would it be easier to strip some of the damaged areas of varnish or just sand it? How can I tell if I need to do some repair to the epoxy? When would it be appropriate to just add epoxy gel and when do I need to add the fiberglass cloth? Once I've fixed the damaged areas, do you recommend an overall coat of varnish to the bottom AND inside?
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Reed,
I don't think I would use a chemical stripper, I'm not familiar with them, but if you wanted to strip the entire boat because it looks like there are 8 to 10 coats of varnish on it that have yellowed and cracked, then a liquid stripper might be the way to go. However, it may raise the grain on the handrails. A nice, very sharp wood scraper might work as a safer alternative to the chemicals. For small areas, just sand it.If, as you say, there are some dark areas of wood, then there probably are some breaks in the epoxy that are admitting water and needs repair. Gently work a chisel into the crack and by working down the edges into a flat hole, enlarge it until you have uncovered the dark area and slightly beyond. Sand it to feather the edges.
Once you have a dished-out hole in the skin of your boat, you need to refill it with two layers of cloth (if it's on the bottom, one layer on the side) and epoxy. Laminate the cloth into place with a small batch of resin, allow it to gel, then fill the cloth texture with more resin. It's best to tilt the boat at an angle so that the patch is level and the resin doesn't run off. I wouldn't add just resin unless it were to fill superficial scratches, under the stems for example. Breaks in the cloth need to be repaired with cloth.
The epoxy has to be protected with at least 2 to 3 coats of varnish, and I would use Z-Spar Flagship varnish. It costs alot, and it's worth every penny. The inside of the boat may be exposed to more UV damage than the exterior, and the handrails really take a beating.
Good Luck!
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Reed replied:
Since writing, I've gotten into the project and have two followup questions. I can't believe I waited until age 43 to discover the beauty of wooden canoes. I find myself out in the shop two or three times a day running my hands over the hull ... kinda wierd.It turns out that the delaminating areas on the bottom are probably a polyester gel and not epoxy. I've discovered that the weak areas seem to pry up with a plastic scraper without taking wood with it. I assume that it's OK to sand down through the final layer of glass to the wood if necessary to repair damage?
Another question ... if I have a rectangular area on the bottom (underside), let's say 6" by 12" ... do I apply the first layer of cloth to fit neatly inside the dished out hole and the second layer slightly larger to overlap the edges of the hole?
Also, I've heard of System Three, West, and MAS epoxy brands ... any preferences?
If I sand down to wood, can the epoxy resin be applied directly to the wood or does the wood need to be prepped somehow to receive the epoxy?
Thanks again!!!
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Dear Reed ,
About running your hands over the hull: canoeing and canoe-building is very tactile-kinesthetic. Welcome to the club.I wondered about your resin, considering that you had an "older stripper." Polyester should be stripped off entirely (yes, the whole boat!), and replaced with epoxy. If you just patch one area, another area will delaminate next year, and you will have endless headaches. The exterior should be fairly easy to do, the interior would require the removal of all the seats, thwarts, and gunnels. Is it worth it? It's a nasty job.
Most of the polyester will peel off like a banana skin, but some areas will start pulling up wood fibers. At that point you can either sand down to the wood, or you can use a heat gun (hair dryer) to soften the resin enough for it to let go of the wood.
Yeah, apply the first layer of cloth to fit neatly inside the dished out hole and the second layer slightly larger to overlap the edges of the hole, but like I said, patching it will be endless.
About resins, System3 is cheaper, clearer, more flexible than WEST. MAS is too cheap, I don't trust it. It has a slow rate of gel and cure.
Yes, the epoxy resin can be applied directly to the wood. I'm sorry to have to tell you this, but I would suggest that you start from scratch and build your own stripper. All you have here of value are pre-assembled wood parts that will require ALOT of work to become bare wood again. If it were of extreme sentimental value, maybe it would be worth it.
Good luck,
David
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Thanks for the advice. Actually, I'm enjoying the rehab job too much to abandon it. Plus, the interior finish is nearly flawless and needs no work ... the only problems appear to be on the bottom. I will attempt to remove all (or nearly all) of the polyester. It is coming off, if a bit stubbornly.I have a wetland behind the house that I plan to use this old stripper to access - a boat I can beat up without worrying about it. But I suspect that this will be a passage for me to attempt a new cedar-strip project next time from scratch. Thanks again.
Reed
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