Sail Camber

by Dave Acree

I have recently talked to several individuals on the need for more "how-to" articles. The MMYC Newsletter has tried to help fill this void and will keep trying. So I chose sail making because this is the one area which is a mystery.

Before jumping off into construction, we need to go over basics of sail design. By no means am I an expert so most of the information will be from the book "Sail Power" by Wallace Ross and several past AMYA articles by Bill Webb, Bill Mercer and Bob Jensen. The difference is putting together the information with my experience I'll try to make it all understandable.

First the basic overview of what makes up a sail. A sail curvature is called Draft. It is compiled from the depth of the curve and the length of the chord. The Chord is length of a straight line from the sail's luff to the leech. Depth is the perpendicular measurement from the chord to the deepest point of the sail's curve.

All this relates to the Camber Ratio, how deep or shallow the sail's curvature is. It is the measurement for only one curvature at one height in a sail's section. Now the equation:

camber ratio = depth / chord

.625 / 10 = .0625

We need to percent the results by multiplying by 100, this will give the Depth or Camber of 6.25%. For what we want to do, if you want fuller sails the more camber; for flatter sails the less camber. Below is an illustration to help explain the sail design concept:

It would behoove anyone who is interested in sail making to go to the library and study the concepts more in depth. It would give a better overview to make the task easer. Next month we will continue on one more design concept and start on the construction. I have to admit, there are some parts to making sails which are a little difficult but with a little effort those can be over come.

For me as I'm sure with many people, why make sails, they do it for fun, cost savings and for the tinkering.