Hydrofoil boat

An improved hydrofoil boat having lateral, longitudinal and vertical axes comprising:

• a hull member;
• a tail boom member attached to said hull member and extending rearward;
• ducted fan propulsion means for moving said boat through the water, said propulsive means being connected to said hull member;
• hydrofoil means connected to said hull member at an angle of inclination to the lateral axis of the boat and at an angle of sweepback from the lateral axis of the boat, said hydrofoil means serving to hydrodynamically support the boat;
• banking means connected to said hull member and to said main hydrofoil means, said banking means serving to bank the boat about its longitudinal axis;
• yawing means connected to said tail boom member and to said rear hydrofoil means, said yawing means serving to create a yawing moment about the vertical axis of the boat, and
• control means for simultaneously and proportionately activating said banking means and said yawing means to produce coordinated turns by the boat with a single movement, said control means being connected to said hull member, to said banking means and to said yawing means.

A method of controlling a hydrofoil boat having lateral, longitudinal and vertical axes, including the steps of:

• providing a hull member and propulsive means attached thereto;
• providing hydrofoil means for hydrodynamically supporting the boat;
• providing means for connecting said hull to said hydrofoil means at an intersection;
• providing means for steering the boat;
• and moving said hydrofoil means selectably between a submerged position approximately parallel to the lateral axis of the boat, wherein said hydrofoil means and said intersection are submerged, and a surface-piercing configuration wherein said intersection and a portion of said hydrofoil means are above the surface of the water, whereby the optimum hydrofoil configuration may be selected for various operating speeds, water surface conditions and water depths.

A low drag method of yawing a hydrofoil boat about its vertical axis including the steps of:

• providing a hull member and propulsive means attached thereto;
• providing hydrofoil means connected to said hull for hydrodynamically supporting the boat;
• providing a submerged hydrofoil wing having a fixed positive dihedral angle connected to said hull member at a horizontal distance from and aft of the center of gravity of the boat and at a vertical distance below the longitudinal axis of the boat;
• and
• rotating said hydrofoil wing about a line approximately parallel to the longitudinal axis of the boat to create a side force to yaw the boat.