Sail Design Basics II
Categories:
Builder’s Corner | Sails
by Dave Acree
Now we have a basic overview of sail design, how is it applied to actually making sails? Remember, a sail has a curve or camber in it but how does that curvature get put into a sail? Sails made for model yachts are constructed by using panels. The use of panels and how they are put together, will give the sail the curve it needs. That is what this issue is about.
Of all the topics of sail construction, how to put in the curvature is most important. It is done by using a technique called broad seaming. Instead of using a template or pattern to cut a panel's curve, the panels are put together on a broad seaming molding block.
Cutting and sewing the curve for model yacht sails is difficult but by making a broad seam sail block, makes the job easy. To start, select some soft wood for construction, such as pine. The length should be 19 inches or enough to complete the longest seam for your sails. For width, I feel as wide as possible. Our block will be in two hales, with curved mid-point duplicating the shape of the sail's curve. At this curved mid-point, each side tapers off 3 degrees from the centerline. There is the overview, now the construction.
To start, cut 2 pieces of wood to the size of 3" x 3" x 18". Then trace the outline of the pattern on each of the two pieces. Cut the right piece first with the bandsaw at a 3 degree and angle then cut the left piece second also to a 3 degree angle, see Figures 1 and 2. Once this has been done, glue the 2 pieces together with the 2 centerlines touching, see Figure 3.
One item to point out when cutting the 2 pieces. When cutting the pieces with the 3 degree angle make sure you cut the angle correctly on each of the 2 pieces. Once the 2 pieces have been glued together, sand the angles of each side with a sanding block. When sanding, test the angle with a straight edge to make sure the surface angle is good. See Figure 3 to see the 2 halves together.
One last point about building a sail block, I like a wide block, 4 to 6 inches in total width. The reason for this is it gives a better platform to lay sail panels on. My first block was only 2" wide, each side being only 1" wide, the panels wanted to fall off in the center. A wide block, 2 to 3 inches for each side allows the panels to rest without falling. Think about it. Well next time we'll start putting the panels together.
Now we have a basic overview of sail design, how is it applied to actually making sails? Remember, a sail has a curve or camber in it but how does that curvature get put into a sail? Sails made for model yachts are constructed by using panels. The use of panels and how they are put together, will give the sail the curve it needs. That is what this issue is about.
Of all the topics of sail construction, how to put in the curvature is most important. It is done by using a technique called broad seaming. Instead of using a template or pattern to cut a panel's curve, the panels are put together on a broad seaming molding block.
Cutting and sewing the curve for model yacht sails is difficult but by making a broad seam sail block, makes the job easy. To start, select some soft wood for construction, such as pine. The length should be 19 inches or enough to complete the longest seam for your sails. For width, I feel as wide as possible. Our block will be in two hales, with curved mid-point duplicating the shape of the sail's curve. At this curved mid-point, each side tapers off 3 degrees from the centerline. There is the overview, now the construction.
To start, cut 2 pieces of wood to the size of 3" x 3" x 18". Then trace the outline of the pattern on each of the two pieces. Cut the right piece first with the bandsaw at a 3 degree and angle then cut the left piece second also to a 3 degree angle, see Figures 1 and 2. Once this has been done, glue the 2 pieces together with the 2 centerlines touching, see Figure 3.
One item to point out when cutting the 2 pieces. When cutting the pieces with the 3 degree angle make sure you cut the angle correctly on each of the 2 pieces. Once the 2 pieces have been glued together, sand the angles of each side with a sanding block. When sanding, test the angle with a straight edge to make sure the surface angle is good. See Figure 3 to see the 2 halves together.
One last point about building a sail block, I like a wide block, 4 to 6 inches in total width. The reason for this is it gives a better platform to lay sail panels on. My first block was only 2" wide, each side being only 1" wide, the panels wanted to fall off in the center. A wide block, 2 to 3 inches for each side allows the panels to rest without falling. Think about it. Well next time we'll start putting the panels together.