The stems are the structural members that tie the ends of the canoe together. There is an inside stem which all the strips that make up the hull are joined to at each end. Then once the strips are fastened down, an outside stem caps them all off so you don’t see the end grain. This outside stem is what takes the abuse to keep those fragile strips from taking any.
Because the stem profile at the ends of the canoe has such a sharp curve over a short distance, the stems need some help to bend without breaking. The first help is that they are made out of three thinner strips which will be laminated together with epoxy, as opposed to one solid piece of wood. The second is that those strips get steamed, which softens the lignin in the wood and lets it compress and stretch more more than it normally would.
The apparatus you see there is my steaming setup. It’s our kettle on a portable one burner grill, with a large piece of pipe and some rags. Pretty sketchy huh ?
After 20 minutes in the steam tube the bundles of strips came out decidedly more noodley. The effect only lasts as long as they are hot though, so you really have less than a minute to make them bend to the shape you want. I had the stem molds clamped in place, and all my clamps pre-set standing by. You need a lot of clamps for building canoes.
Each time I did this I had a helper to put the clamps on while I bent the hot strips around the mold. I’m not sure how you’d do it by yourself.
After a full twenty four hours of drying the clamps come off and the strips have held their shape mostly. They still have some spring back but you can easily push them into place with your fingers. They got tied with some string to hold their shape and I’ll wait a few days before epoxying them together to make sure all the moisture is out of them.
