Multihull sailing craft and hull structure therefor

In a multihull sailing craft capable of sail-powdered speed through the water greater than displacement hull speed, a plurality of sponsons or amas, each said sponson or ama comprising a sponson or ama hull having:

• (a) a generally stepped-V lateral half-cross section, which provides a plurality of generally longitudinal lift-producing hull steps extending generally horizontally outward from the longitudinal center line of said sponson or ama hull and along a major portion of the length of said hull, said hull steps being configured, in their generally horizontal surface area in relation to the hull length, and in their angle of attack, to produce a hydrodynamic righting moment at semi-planing speeds of said sailing craft through the water, with a lift/drag ratio favoring semi-planing speeds and stability at said speeds, said hydrodynamic righting moment being generated generally in direct proportion to the generally horizontal wetted surface area of said hull steps times the square of the semi-planing speed through the water;
• said hull steps being integral with said hull and shaped to be generally decreasing in lift-producing and drag-producing width as they approach the stern of said hull, until said width is essentially zero, the generally horizontal planes of said hull steps describing a rotational movement toward the planes passing through the legs of the V-shaped lateral cross-section of said hull as said hull steps approach the stern of said hull until said generally horizontal planes are not visible at said stern;
• and
• (b) a length-to-beam ratio greater than 10:1, said ratio being selected to minimize hydrodynamic drag at said semi-planing speeds consistent with adequate hull buoyancy for stability at said speeds.