Monday, August 25, 2008

Building a Cedar and Canvas Canoe : Monday

I've just returned from another trip up the the WoodenBoat School in Brooklin, Maine. As I noted in my post below, I was taking Jerry Stelmok's class in cedar and canvas canoe building. I've done repair work, but never built a boat from scratch. This was an excellent opportunity to learn the whole process from one of the experts in the field.

On Sunday evening, we met as a class and introduced ourselves and discussed our experience and why we wanted to take the class and what we expected to take away with us.

On Monday morning, we got started in earnest. In the picture below, you see the pre-bent stems, planking and rib stock (cut to rough dimensions) a roll of canvas, and a box which contained seats, extra tools and hardware for three boats. The boats that were built included an Atkinson Traveler (17') , a Model 1889 (16') based on an early EM White design and a solo boat, the Sojourner (13')

The next image shows the end of one of the forms. In this case, it is the Model 1889. What you are looking at is a rigid mold made from a plywood skeleton covered with bent white pine strips. Over the strips are metal bands to clench tacks (more on that later), mounts for a clamp to hold the ribs in place and features to hold inwales and stems in their proper locations. The form is the key to building a good canoe. If this isn't true and straight, the boat will not be either. These forms were (and are) passed down from generation to generation. Some are over a hundred years old and still used to make boats.

The first major task we had was to cut the rib stock to length. This stock is Northern White Cedar. To do this there were measurements on the 2-by used to clamp the ribs in place. We added a few extra ribs in case we broke some as we were building the canoe. The length of the ribs is 4" longer than the distance from gunwale to gunwale. The goal was to have ribs that were vertical grain in the middle and transitioning to flat grain at the ends.

Once the ribs are cut to length, they are then tapered using the jig shown below. This cuts the ends of the ribs down to 1-3/4" at the ends by removing material from one side of the rib. The table saw's throat plate is deliberately removed to allow the wedges to drop free and not jam or kick back at the operator. Two ribs could be cut at a time and knots and bad edges were removed at this time to get nice clean looking ribs.

The ribs were then rounded over a bit on both edges with a router table. The bit was about a 1/2" radius bit and we only used a small portion of it. A stack of ribs can be seen on the table in the rear center of the picture - note the taper at both ends.

After shaping the edges of the ribs, both the finish face and the edges of the ribs were sanded with 100 grit paper. Tedious, but not difficult work with the soft Cedar.

We then installed the inwales on the mold. These are made from Spruce for their light weight and strength. The inwales used on the 1889 had been pre-bent with a steam box to put some of the curvature into them before mounting. We also tapered the inner ends of the inwales as shown below to make the ends "finer". The outer surface of the stem was then coated with shellac to waterproof them.

The pre-bent stems were made from Ash and were made with enough width to get out two stems from the one piece. This is done to prevent the stem from twisting as it is being bent. The bent stem is then cut to width on the table saw. The stem is then cut so it fits into the notches on the ends of the form and marked for the rib positions with a simple gage that looks like basically like a piece of rib. The notches are cut on the bandsaw and are a bit generous to allow for rib growth during the steaming process. A bevel is then cut using the bandsaw that fades out before reaching the first notches. The stem is installed on the form and the edges of the notches are relieved with a rasp to allow the smooth bending of the ribs. The partially finished stem is shown below.

After the stems and inwale were installed, they were wired in place on the mold to hold their shape and position.

To fill the end of the day, the planking was sanded on the finished or inner surface as this would be a difficult area to sand between the ribs after the planking is installed. Again, we sanded with 100 grit paper using random orbital sanders.

At this point, all of the major hull stock has been completed and is ready for installation.

One of my favorite things about the process is the smell. The Northern White Cedar is a lovely smell as you work it. Also, it isn't as splintery as Western Red Cedar that I use to build my cedar strip canoes.

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