One problem with using triangular templates or stencils to lay out a triangular design such as OT's design # 4 arises from inevitable errors in measurement. It is difficult to get a precise measurement of the curved sheer line of a canoe, and any error in the dimension of a triangular template baseline will be multiplied by the number of times the template is used. For example, if painting design #4 on a hypothetical 18' canoe (216"), with a hypothetical sheer line of 202" requires 43 large triangles under the gunwale, each triangle base will be 4.7 inches. If an error as small as 1/32' is made in creating the template, the accumulated 1/32" error of 43 triangles will be 1 and 11/32" -- more or less, depending on whether the error is plus or minus. Starting at one end of the canoe, even with a template error of as little as 1/64", you will be about 11/16" short or over when you get to the other end. As Gil Cramer notes in post # 8 above, it may take a couple of tries to fuss and fudge to get the triangles to come out properly.
I have used an alternate method that does not require using templates, and accommodates and hides small errors as you make the single layout effort. All that is needed is a tape measure, a small square (or square-cut piece of cardboard or wood), masking tape, and pencil or washable marker.
First, determine the size of the triangle you wish to use -- for the hypothetical canoe above, the base of the triangle will be about 4.7" and its height will be 3".
Next, determine the center of the sheer under the gunwale and mark with a pencil. Then, mark the ends of a line 4.7" long centered on the already marked center point of your sheer under the gunwale. This two points will identify the base of your first, central triangle -- leaving you with the bases of 21 triangles to mark out on both sides of the central one.
Next mark the ends of a 4.7" triangle base at the bow and at the stern -- leaving you now with 20 triangles to place between these and the central triangle. Divide this distance in half, giving you a space into which 10 triangles will fit. Mark the center of this, and you have the space for five triangles.
Now measure this distance, divide by 5, and mark the 5 triangle bases -- do this separately for each segment of 5 -- the distance is not likely to be exactly the same, but the difference, divided five times, will be negligible. And when actually marking out the 5 bases with your pencil, minor fudging is easily done by eye if needed so the five triangles fill the segment.
Next, mark a line 3" below the sheer under the gunwale -- I made a series of pencil dots using a short story stick, and connected them with masking tape.
Now go back to each of your 43 triangle bases, and mark the center of each. Using your square. use this center point to mark the point of the height of your triangle along the masking tape. (As seen in the photo, I marked the base of each triangle and its center on the gunwale, which was to be painted over. The point of the triangle was on the long masking tape, covered by the subsequent taping.)
With masking tape, connect the ends of the base of each triangle with the apex point marked on the masking tape 3" below -- then paint.
My paint job is an adaptation of design #4 -- obviously, the colors are not the classic red, white, and blue. Further, my small (green) triangles are not separated from the larger triangles as much as in the classic design, and they are not as small as in the classic design. Had I used wider masking tape (perhaps 2" instead of the 3/4" tape I used), or separately masked for the small triangles, I would have come very close to the proportions of the classic design.
This all seems like a lot of work, but it is not difficult. I suspect using templates is at least as much work. I have never tried using templates, so I cannot say that this method is easier or better -- but it does get the job done.
