Rot in a Wood-Canvas Canoe: Causes, Prevention and Repairs
August 10, 2012
by Mike Elliott, Kettle River Canoes
Wood-canvas canoes, by their very nature, are subject to rot. The problem is not entirely avoidable, but can be reduced. Once every thirty years or so, damaged areas can be repaired.
Wood rot is caused by a number of fungi (Serpula lacrimans, Poria incrassata and Gleophyllum trabeum are among the most common). The results turn solid wood brown and crumbly. As you disassemble the canoe for inspection, affected areas often break apart into cubes when disturbed.
These fungal spores are almost always present, but can only grow when certain conditions exist. Wood rot fungi need three basic ingredients in order to grow: 1) moisture; 2) no air circulation; 3) a warm environment. Parts of your canoe (such as the outwales, stem-tops and inwale-ends) are normally covered and protected. If these areas are allowed to stay warm and moist, they become prime environments for fungal growth – in other words, rot heaven.
To prevent rot from forming in your canoe, store it upside-down off the ground in a cool place that has lots of air circulation. A lean-to shelter next to the house makes an excellent canoe storage area as does a carport. Proper storage of your canoe is your prime defense against rot. Another step is to maintain the exposed wood with a fresh coat of spar varnish every few years.
When restoring your canoe, a number of things can be done to both repair the damage and prevent rot from developing in the future. First, use an epoxy sealer or wood hardener to solidify the wood in areas that are likely to rot at some point.
Areas already rotted must be cut away before starting repairs. Once you are back to solid wood, scarf in new wood and rebuild the affected areas.
Once the repairs are complete, apply a combination of boiled linseed oil and turpentine to all exposed wood. It doesn’t stop water absorption completely, but it is a great preventative measure. As a general rule of thumb, it is best to seal a component before attaching it to the canoe. For example, many outwales look great from the outside. However, water can get trapped under them and allow rot to attack the bare wood on the inside surface. If you seal the entire outwale before it is attached, water cannot get to the wood on the inside surface which means that rot cannot develop there.
“The canvas is shrinking and pulling away from the gunwales on my wood-canvas canoe. What do I do to fix it?” I get this question fairly regularly. Fortunately, it is a common problem with a straightforward solution. However, it is usually not what you want to hear. The canvas does indeed look as though it is shrinking and pulling away from the canoe. It gets loose and starts to crack in places as well. The answer is simple enough. Over the years of use, water gets trapped under the gunwales and creates a damp environment – perfect for rot. Since the only thing holding the canvas to the canoe are a bunch of tacks, as it rots and it breaks apart, it simply falls away from the canoe.
August 11, 2012 at 12:26 pm
“Wood-canvas canoes are, by their very nature, subject to rot.” Nonsense. Any builder of wooden boats will tell you that rot is likely to occur in wood that is poorly ventilated in a space where water tends to be trapped. And that’s what you get when you put decks on the stems of a wood canoe: a poorly ventilated space that traps water. No wonder you get the “inevitable rot” at the stem heads. Take a look at a birch-bark canoe. There are no decks! Decks are just not a necessary structural item! The professional canoe restorer (and I am not in this class) may have reinstall the decks in order to bring the antique canoe back to original specs. As an amateur repairer, I don’t have that problem. I cut off the pointed ends of the decks thereby leaving a small, but essential, ventilation hole.
August 11, 2012 at 11:54 pm
Wow, did you even read the article??? Mike said that the key to keeping rot to a minimun over perhaps 30 years, is to re-varnish every few years, as well as storing properly in a place with cool temperatures and good circulation. Also, the builders of wood and canvas canoes (who have been building them for more than 100 years) have always put decks on them; I should think that they probably have a better idea of how to build a canoe, than you (an admitted amatuer) do. It always pisses me off, when people who don’t know, and don’t listen, start expounding their great knowledge, when they obviously don’t know what they are talking about. Keep-up the Great Professional Work Mike……
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August 12, 2012 at 12:10 am
yes, I read the article. Did you look at the pictures? Over and over again we see photos of carefully maintained canoes with severe rot in the stem ends. I stand by my belief that this rot is due mainly to the decks creating an area of poor air circulation where water can become trapped as well. (And, of course, you cannot easily varnish that enclosed wood.) Its a simple matter to create or leave an opening at the stem head, but no builder or restorer seems to want to do that. I also stand by my belief that decks are cosmetic rather than structual. As I pointed out, birch canoes do not have decks.
Allen, instead of getting “pissed off” and accussing me of not knowing and listening, you might think about the logic of what I am saying.
Regards,
Jeff
August 12, 2012 at 2:34 am
Listen to yourself!!! First you say that wood and canvas canoes, by their very nature, are not subject to rot; now you say that you keep seeing all these pictures of canoes that have been well looked after and carefully maintained, that are rotted-out, because of the way they were built (???????) I have a 40 year old Tremblay that I am restoring, which has many broken ribs, but almost no rot what so ever. the only place there is any rot, is in the outer gunwales and rib tops (where the gunwales rotted. The pictures that you are looking at, are canoes that have not been looked after or maintained. Cedar will last 25 years buried in the ground, so if you look after your canoe, and maintain it, it should last easily for 30+ years. Clipper makes a great canoe for people who bring their canoe home, and throw it by the woodpile in the back yard.
Keep up the “Great Work Mike”.
August 14, 2012 at 8:52 pm
At this point in the lively debate between Allan and Jeffrey, I’d like to wade in with a few comments and clarifications — for what it is worth.
When I said, “Wood by its very nature, is subject to rot.” I was attempting to allude to the fact that wood is dead plant material and as such, and under the correct conditions (moist, warm, little air circulation), is a growth medium (i.e. food) for a variety of fungal spores. The subsequent process turned the wood into compost.
To prevent attack by the fungi, you can do two things: 1) store the canoe in cool, dry conditions with lots of air circulation and; 2) while repairing the canoe, apply oil, shellac and varnish to all of the surfaces of all of the end-pieces (decks, inwale-ends, stem-ends).
With the components (including the decks) completely sealed, water and fungal spores cannot get into the wood. I choose to do this rather than creating a ventilation port by cutting the ends off the decks. To me, since you are already there with the components taken apart, it makes sense to simply seal the parts before assembling the ends.
I suppose that cutting the ends off the decks would work, but to me, that would be similar to drilling holes in your teeth to prevent tooth decay. You haven’t really addressed the fundamental facts — you still have exposed bare wood which, given a moist, warm environment with little air circulation, would still be composted by fungal growth.
Also, for the record, the pictures of the rotted canoe ends were taken of canoes that were anything but well-maintained or well-stored — that’s why they rotted.
August 17, 2012 at 2:08 am
Exactly!!!!! If you treat your canoe like a piece of crap, it’s gonna become one. Take care of it, and with a litlle maintainance (like you need to do to your car) and it will last you for many years….Again, Clipper makes a great plastic canoe for the person who brings it home and throws it outback by the wood pile for the next 6 months…… “DOH”…..
August 17, 2012 at 2:26 am
Also, the decks on many canoes are not “only cosmetic”. They provide structural supoort for the entire stem ends. On my Tremblay, the stems are anchored directly to the tip of the deck; if you cut the end off of the deck, the stem would be more or less “floating” without the extra support.
Keep up the great “Professional Work” Mike
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August 17, 2012 at 2:49 am
Rot at the canoe tips does not start from the inside out. Just the opposite. The outwale tips suffer first, then the inwale and stem tips go next. The last to rot is the deck surface, not the deck interior. Why? There is no moisture trapped on the inside. It is the external moisture that causes the damage. When a unprotected canoe is stored upside down in the weather the moisture will migrate to the lowest outside points thus, in time, causing the damage. Cutting off the ends is to stop the rot………. what have you been smoking?
August 17, 2012 at 5:43 am
Nicely said….
It’s all about maintainance 