Unless the context of the text requires otherwise, the term “craft” means any vehicle, watercraft, or ice craft. Examples of a vehicle would include wheeled vehicles and the like. Watercraft comprise by way of example, without limitation single, multihull and hydrofoil vessels. As used herein, ice craft comprises vehicles having skis and/or skate like blades for traveling over ice or snow surfaces.
As used herein, the term “mast” will mean a rigid structural member projecting in a generally vertical direction from a deck or base to which it is attached. A “stay” is a rigid or flexible structural member providing lateral support to a mast to which it is attached. A stay is generally attached to a mast at a point away from the mast's point of attachment at a deck or base, that is, up the mast, and secured to the deck or mast away from, or distal to the attachment of the mast to the deck or base.
As used herein, the term “sail” means a flexible sheet in the nature of fabric, membrane, or sheet used to capture wind or provide an aerodynamic lift. The term “lift” is not intended to denote an upward force, but rather refers to a component of the force that is perpendicular to the oncoming flow direction of air movement over a surface.
It is desirable to have rigid aerodynamic lift surfaces that can be carried or mounted to a mast and controlled through all wind directions. That is, the aerodynamic lift surfaces can assume a power position generating lift or a non-power position in which the aerodynamic lift surfaces do not generate substantial lift.