Future Physics of the Birdwing Mast

An inventor’s perspective

- Ken Ford

The birdwing mast is my nickname for a storable, sickle-shaped, sailboat mast. In the U.S. patent I have for the design, it is described as utilizing an aerodynamically efficient cross-section along its length. There is no limit in the patent for the sickle shape— meaning that a birdwing mast can be any sickle shape ever created in the past or even any created in the future. If you do an image search for “sickles,” you’ll begin to get an idea of the range of possibilities for a birdwing mast. There are hundreds of them.

Why the sickle shape? I knew I wanted the mast to be curved to better conform to the gunwale of my little fishing skiff(when mast was down)so that my fishing buddy of 20 years would stop complaining about the old straight mast being in his way. (After a few beers he’d become especially effective with his complaining, so I decided it would be easier to design a curved mast than to train a new fishing buddy.) This first new mast was 100% successful as it curved completely out of his way…and peace while fishing was once again restored.

Even though I was a novice sailor at the time, I’d taken enough physics courses to realize early on that the curvature would probably be fine for windward work, but that the mast would definitely have to rotate to be effective for downwind work. And then I had one of those eureka moments late one night while staring at my boat—a sickle shape! If there was a little straight section at the bottom of the mast, that would allow the mast to rotate in its step and I could keep the peace-restoring curvature without giving up any performance. In fact, later I realized this swept-back curved and rotating shape could improve aerodynamics for setting sail when compared to a conventional straight mast.