Sail Battens by Bob Ramsay
As there are a wide variety of sails used on Paper Tigers, this article should be taken as a guide only. Most battens used in PT sails are fiberglass with some foam sandwich type battens also used. As this type of batten cannot be effectively shaped, only the fiberglass type will be considered here.
Glass battens can be easily shaped. Rough shaping can be done with a surform rasp or even a plane. Finishing is done using an abrasive paper on a block.
While shaping, lay the batten on a flat surface and Endeavour to take similar amounts from both sides. Initially the first one third of batten should be tapered, and while doing this the flexibility and shape should be checked using a set of kitchen scales or small spring balance. Figures 1 and 2 show the method. When using the figure 2 method, the weight of the batten should be deducted from the reading or the scale zeroed with the batten resting on the pan.
Endeavour to get the position of the maximum camber approximately 40 - 45% from the front of the batten (see Figure 3). The stiffness (scale reading) should be between 0.5 and 1.5kg depending on the sail and your preference. Endeavour to keep all battens (except the top two within a reasonable range so that if the sail maker has done his job the sail will be uniform in shape. The top two battens will probably need to be stiffer to support the leech. It is most important that the battens have a uniform curve, that is, don't end up with a big bend at the front and the back section practically flat as shown in Figure 4, or have a flat entry as shown in Figure 5. Both these shapes make for very slow sails. The final shape should be similar to that shown in Figure 3. The shape can be checked by pushing the batten against something rigid, the curve can then be traced on paper or with chalk on a floor. The position of maximum camber can be readily determined after the chord is drawn (refer to Figure 3).
If you make a mess of the battens or want to change an existing set it is often possible to get away with buying one or two lower battens and moving the existing ones up the sail.
The battens should be tied with enough tension to remove the creases from the sail cloth around the batten and to initially apply a small amount of tension to the sail cloth. If the battens are correct the sail should have a uniform, even shape.
(This article was first printed in the October 1992 edition of “The Paper Tiger Paper” newsletter of the VPTCA)