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.