Abstract: High performance sailing yacht designs are disclosed based on a keelless sailing yacht concept having dynamic gravitational ballast which is laterally movable for heeling resistance which ballast replaces a function of the standard keel. A keelless yacht of this type is disclosed with an adjustable flap mounted on an elongated strut from which the ballast is suspended below the hull to generate a variable heel hydrodynamic control force independently of the counter-heeling effect achieved by the ballast. The foregoing features enhance the effects of disclosed improvements and modifications to hull design in having a duplex form, with upper and lower hull shapes, the lower of low drag shape, and of reduced section, while the upper hull extends laterally abeam from the lower hull to define reserve buoyancy, added accomodation, and surfaces adapted for hydroplaning when the yacht is at a controlled angle of heel.

Abstract: High performance sailing yacht designs are disclosed based on a keelless sailing yacht concept having fore and aft cambered foils for leeway control which foils replace the function of the standard keel. A keelless sailing yacht of this type is disclosed with dynamic ballast which is laterally movable to apply a variable counter-heeling force; a tiltable mast which may have a rotatable mast and sail leading edge; cambered foils for cyclic and collective steering; and adjustable camber controls for adjusting lift and leeway. The foregoing features allow disclosed improvements and modifications to hull design in having a duplex hull form, with lower and upper hull shapes, the lower of low drag shape, and of reduced section, while the upper hull extends laterally abeam from the lower hull for added buoyancy when heeled and for accommodation room.