Canting sailboat masts are a relatively new invention, being extensively developed and adopted right now to many different hulls. This is mostly a raceboat technology but I recently helped design a fast cruiser that has one, so the tide may be changing. The cant masts I am referring to are those that cant port and starboard, laterally across the boat centerline. Masts that tilt for and aft have been around for centuries on proa’s and other Polynesian craft. Modern cant masts trace back to Peter Adriane’s Open 40 race boat Syllogic. Syllogic sports a stayed canting mast, that means the mast pivots on deck and the pivot is controlled by the stays that would hold a normal mast upright.
Cant masts have great advantages over regular masts, for one the mast can be canted to windward, thereby increasing the apparent sail area. As the boat heels, normal masts become less efficient and induce drag and stress by trying to force the boat under the water due to the pressure created by the air flowing over the top of the sail. Cant masts keep the sail closer to vertical, increasing efficiency and reducing the down force on the hull. They can also increase efficiency by canting the sail to windward, this increases the apparent sail area, to more than the static sail area. When the mast is canted to windward it also decreases drag by lifting the hull instead of forcing it down. It works just like a windsurfer does, in fact windsurfers use cant masts and they have been around for a long time.
Cant masts have lots of benefits and also lots of downsides. To make a heavily loaded column cant takes tons of engineering. The structure is very complicated and is subject to Murphy’s Law. Unstayed canting masts are very, very sleek and about 10 times as complicated as a stayed canting mast. Not only do you have to make the mast strong enough to support the weight and pressure of the rig, you have to figure out how to tilt this thing and encase all the parts below deck and using as little electricity and weighing as little as possible.
Like everything else, masts are a compromise. Static masts work very good running in many sea and wind states and headings while a cant mast is really only an advantage while running up-wind or close-hauled. Boats that sail mainly downwind have no real use for masts like this, but would benefit from a canting keel.
So basically a canting mast is a normal mast that tilts side to side on a sailboat. Right now only race boats have them, but there is at least one cruiser being built with one; I hope to node it after she is launched in late July of 2003.