Forms are marked out

This week I've been working on transferring the lines from the plans to plywood for the forms. This will be covered in more depth later, but the forms are patterns that are placed about every foot on the strong back. The cedar strips are laid over these to create the shape of the canoe. The shape of the forms is taken from the lines of the plans. It's possible to buy pre-printed plans for canoes and boats, but one of the reason's that I chose to build the "Bob's Special" is because the lines were available for free from the book "Canoecraft" by Ted Moore, which I checked out from the library. The book didn't contain actual plans or lines at all, but a table of numbers called "offsets". These allow you to graph out points along the lines, which you then connect using a batten, a flexible strip of wood in a process called "lofting". To keep the batten from moving while you play connect-the-dots, nails are driven through the points graphed out, the batten is placed against them on the poster-board, which is tacked to some plywood, and then more nails are driven against the other side of the batten to hold it in place. Since the canoe is symmetrical side-to-side, only one side is drawn to save time and resources.

This process is called "lofting" because it was originally done in lofts over the floor of the buildings where construction was taking place in the boat-yards and boat-sheds.

The process of transferring lines to plywood to mark out the forms is very similar to lofting the lines. The poster-board with the lofted lines is tacked down to the plywood with the baseline of the plan and the bottom of the plywood aligned and the centerline of the plan matched to a line drawn perpendicular to the bottom of the plywood. The batten is secured to the plan and plywood with nails driven on either side of it and the line is drawn along the side of the batten, as in the lofting process. The difference here is that two layers of carbon paper are lain down between the plans and the plywood, so that the line is transferred to both the plywood and the backside of the plans. Then the plan is flipped over, aligned with the center and baselines, and the batten secured along the newly transferred mirror image line with carbon paper between the plan and the plywood to trace this line for the the other side of the form.

Once the lines are transferred to the plywood, another sheet of plywood is clamped underneath with their baselines aligned, pilot holes are drilled, and the two are screwed together. This will allow two copies of the form to be cut out at the same time. Because this canoe is symmetrical fore and aft, two copies are needed of all of the forms except for the center one. This saves time marking a second form, and will later aid in making sure that the two sides are symmetrical.