In this article we give you tips on buying wood as well as suitable wood species for skin-on-frame canoe building. Finding the rightpiece of wood for skin-on-frame canoe building is not always easy. Lengths of over five meters are hard to come by. If also the wood has to be free of cracks and knots and should be durabile enough with straight annual rings, you are a lucky guy if you have found a board that meets all the requirements. We therefore want to sort the priorities a bit to make your wood purchase easier. You probably won't find the perfect board. Small knots, cracks or transportation damages are flaws that any board can have and that you can work around with some clever sawing tactics.
Priorities in buying wood
(1 = high, 5 = low)
1 | crack-free | ​Cracks are always lengthwise in the boards, so you often can't use large sections of the board. |
2 | straight annual rings | ​The annual rings should run parallel to the edge of the board and be as parallel to each other as possible. Only strips with a majority of the annual rings running from the beginning to the end of the strip are stable enough. Annual rings that run out of the board weaken the board. |
3 | lying annual rings | Lying annual rings lie parallel to the longer side in the board or strip, as shown in the sectional drawing below. Very important for stable strips with homogeneous bending behavior, especially for the gunwales. |
4 | knot-free | Smaller knots don't have to be a big problem, but larger ones often are. If necessary, you have to taper long strips |
5 | sufflicient length | If you can't find wood long enough, you can taper short strips to make a long strip |
Standing/lying annual rings - what is the difference?
Difference between standing and lying annual rings: On the left, a board is shown with standing annual rings, i.e., the annual rings run parallel to the narrow sides of the board. On the right, the section through a strip is shown, in which the annual rings lie, i.e. run parallel to the long edges of the strips cross-section.
Buying wood for ribs
The purchase of suitable wood is usually the biggest challenge in steam bending. In specialized stores, you will find almost exclusively kiln-dried wood, which is why only ash comes into question here, since this is the only wood that can be bent relatively well even when kiln-dried. When looking for suitable wood, one must therefore look at the beginning of the supply chain: the sawmill. Here you can have a chance to save fresh boards from the kiln.
For ribs that are to be steam bent, oak and ash wood are particularly suitable. Oak wood must be undried and should have a high residual moisture between 20 and 30%. Kiln-dried oak is not suitable for steam bending. Ash wood is basically the same but kiln-dried ash wood is also suitable for steam bending. In this case, however, you should be prepared for more breaks and rather buy a little more wood. Calculate for one rib with about 1cm board width (6mm rib thickness + 3mm saw blade + safety).
You will hardly find a perfect board that can be completely processed into steam bending strips, since small knots or warps in the annual rings disqualify certain areas in the board. The challenge is to find usable areas in a board that can meet as many requirements as possible and produce good strips.
Optimal are boards that are an inch thick, i.e. boards that have been sawn to a thickness of about 27mm. These can still be processed with DIY machines and already show approximately the required strip width. If planers and thicknessers are available, the board can be planed in advance directly to rib width before the individual ribs are sawn on the table saw.
In the photo you can see a comparison of ribs. On the left strip, the annual rings lie perfectly parallel in the strip. The homogeneous top side is a good indicator. In the middle strip, the annual rings are also parallel in the strip, but one annual ring runs out of the strip because the saw cut did not follow the grain of the wood. At this point, the strip can break or it bends unevenly. In the right hand strip, the annual rings lie diagonally in the strip. Although it is less likely to break than the middle strip, but it bends not as easy and homogeneous as the left strip. The drawing shows the strips in the same order:
Buying wood for the gunwales
For the gunwales light woods are most suitable, because you do not want to increase the weight of the finished boat unnecessarily. In addition, the type of wood should have a certain durability and be easy to work with. Wood types from local production can be, for example, spruce, pine or douglas fir, whereby douglas fir still represents the most durable wood type. The only disadvantage of these species is their knottiness, which often requires tapering. The holy grail of wood species is Red Cedar (Thuja plicata), as this wood is very light, extremely resistant to rotting and easy to work with. Unfortunately, this wood is difficult to obtain in specialized stores in europe. For the production of gunwales, look for a board with lying annual rings, as the gunwales, which are often wider than 50mm, are sawn horizontally from the board. The photo shows an almost perfect board with very parallel annual rings from which four gunwales are sawn (the areas above and to the right are offcuts and can still be used for paddle construction):
Important tools
...that should not be missing when buying wood:
- Tape measure
- Moisture meter
- Cutter knife
- Flashlight
- Hand saw
- Red flag and ratchet straps for securing the load
- Roof rack or trailer
- Tip (can make staff more helpful and patient)