Building a Cedar Strip Canoe: Making the Stems
My Home-Built Cedar-Strip Canoe
This is the last of a series of articles on how I built my second cedar-strip canoe. For an overview, see Building a Cedar-Strip Canoe: The Basics.
Stems Form the Stern and Bow
Stems are laminated strips of wood that form the tip of the stern and bow. The inner stems are where the ends of the strips are stapled and glued, and tie the stripped hull together. The outer stems are glued on top to the inner stems and blended into the stripped hull with planes and sandpaper. They are usually made of hardwood and provide some protection for the soft strips and inner stems from collisions with shoreline obstacles.
For this canoe I made the inner stems with three ¼” strips, two cedar and one white pine. The outer stems were made with three ¼” strips, the outermost being maple and the others white pine.
Steaming the Stems
The stem strips must be steamed and clamped to the bow and stern forms and allowed to dry. Steaming the stems can seem a bit intimidating at first. I made a steamer out of a length of 4” PVC pipe and plugged the ends with a pieces of ¾’ particle board cut to fit with a hole saw. The bottom plug had a hole drilled in it to allow steam to enter the pipe. The source of steam was an old coffee pot with a short length of copper pipe replacing the bubbler. I filled the pot with water and set it atop a Coleman single burner backpacking stove. Once I had soaked the stem strips overnight in water I placed them in the PVC pipe, plugged the end and hung it from the rafters of my garage so that the pipe on the top of the coffee pot enter the hole in the plug. The secret to successful steam bending is lots of steam. I cranked the control of the stove all the way up to get the water boiling furiously. When I saw steam shooting from a tiny hole at the top of the PVC then I knew the steam volume was about right. About 30 -45 minutes is about right. The sides of the pipe will start to get soft.
Clamping the Stem Strips Onto the Forms
The hot strips, all six of them, are clamped onto the forms. Here is where I made a mistake with the forms. I only cut six 2” round holes in the forms, when I should have made them 1-1/2” and spaced them closer. Also I should have cut the first hole near the sharpest bend in the stems so that I could clamp the strips there first. This would have put less stress on the strips when bent since the ends have less distance between them and the form. But I made it work.
Combining the Stem Strips
Once the strips have been thoroughly dried, I glued them together and clamped them back on the forms. I used a mixture of epoxy, sanding dust and bits of fiberglass for the glue. The edge was first covered with plastic packing tape to prevent the strips from becoming permanently attached to the form. Packing tape was also used between the group of three inner strips and the group of three outer stems. This is a messy job and it is difficult to get all the strips aligned.
Shaping the Stems
After the epoxy glue mixture was sufficiently set I removed the clamps and cleaned off the dried excess glue with a sureform plane. I set aside the outer stems for later, and put the inner stems back on the stem form which I reattached to the strong-back table with the rest of the forms.
I attached one end of each stem to the form it butts against with a screw through the form into the stem and attached the other end with a screw through the stem into the stem form.
The stem must be now shaped. I drew a center guideline the length of the stem, and also a line 1/8” to the left and right of it. Using a plane, spoke shave, sureform plane or all three, the stem needs to be shaped to allow a glue-and-staple surface that will be flat where the strips will be attached. The area between the lines needs to be left flat after the shaping is finished. Near the top of the bow or stern the angle is sharper. The stem-to-strip interface should be as flat as possible to allow plenty of area for the surfaces to make contact.
I found that my bow stem form was off a little and I raised one end of the inner stem with a shim. I will continue to make small adjustments like this as the build progresses. It’s just part of building when you are neither an artist or carpenter, but just determined to build a useable canoe.