Various embodiments are disclosed for a stepped cambered planing hull for a boat including a swept back cambered planing surface having a non-linear distribution of camber. The non-linear distribution of camber along the swept back cambered planing surface may enable stepped cambered planing hulls having high deadrise (i.e., greater than 15 degrees). The stepped cambered planing hull may include a shaped hydrofoil that generates further hydrodynamic lift by piercing the free surface wake produced by the swept back cambered planing surface. The stepped cambered planing hull may have external bottom surfaces adapted at the after-body and transom to accommodate a distinctive profile of the free surface wake produced by the swept back cambered planing surface. The stepped cambered planing hull may include an adjustable interceptor blade to regulate hydrodynamic lift at low speeds or to ensure an optimal dynamic trim angle in a wide range of speeds.

A planing boat including: a hull having a boarding area; a screw unit having a screw, and configured to be rotatable with respect to the hull so that the expulsion direction of a water current by the screw can vary by 360 degrees; and a direction change mechanism having a turning drive force source, and configured to change the expulsion direction by rotating the screw unit with respect to the hull with a drive force of the turning drive force source.

A planing boat including: a hull having a boarding area; a screw unit having a screw, and configured to be rotatable with respect to the hull so that the expulsion direction of a water current by the screw can vary by 360 degrees; and a direction change mechanism having a turning drive force source, and configured to change the expulsion direction by rotating the screw unit with respect to the hull with a drive force of the turning drive force source.

The present invention provides a hull-conversion device and method for modifying the underside of a watercraft, more specifically a multihull watercraft. The hull-conversion device comprising a water diverting surface, a kinematic assemblage, and a frame. The hull-conversion device may be operable to adjust the watercraft's characteristics in displacement mode and planing mode. The hull-conversion device may function to provide a more stable, controllable, and efficient platform for operating a multihull watercraft, and provide a suitable wake for towable water sports.

A planning boat includes at least one tank provided on a bottom of the boat. The tank has, at a stern side, a wall through which a through hole is provided below a waterline. A hull of the planning boat includes a bottom plate that forms the bottom of the boat, right and left side plates that form sides of the boat and a bow, a transom plate that forms a stern, and a plurality of longitudinal vertical plates. The plurality of longitudinal vertical plates each extend between the transom plate and forward portions of the side plates along a sailing direction and each have a lower surface that is fixed to an upper surface of the bottom plate. The tank is formed by using the pair of longitudinal vertical plates of the existing planning boat.

A method of operating a boat to produce a surf wake includes partially filling a transverse ballast tank, moving the boat through a body of water, rolling the boat toward either its port or starboard side to shift the water in the transverse ballast tank such that at least some of the water in the transverse ballast tank moves from one side of a longitudinal centerline of the boat to the other side of the centerline, and creating a surf wake on the side toward which the boat is rolled.

A method of operating a boat to produce a surf wake includes partially filling a transverse ballast tank, moving the boat through a body of water, rolling the boat toward either its port or starboard side to shift the water in the transverse ballast tank such that at least some of the water in the transverse ballast tank moves from one side of a longitudinal centerline of the boat to the other side of the centerline, and creating a surf wake on the side toward which the boat is rolled.

System for aiding the planing of a planing boat comprising a hull, having a critical transition speed from a displacement sailing and a planing sailing and at least an internal combustion engine comprising means for transmitting an engine displaced power to the water; transmission means defining a gear ratio and identifying a critical speed of rotation of the engine corresponding to the critical speed of the hull; the system comprises a centrifugal supercharger, for supercharging said internal combustion engine, activated by speed multiplying means to be operating in a predetermined interval of speeds of the at least an internal combustion engine including said critical engine speed.

System for aiding the planing of a planing boat comprising a hull, having a critical transition speed from a displacement sailing and a planing sailing and at least an internal combustion engine comprising means for transmitting an engine displaced power to the water; transmission means defining a gear ratio and identifying a critical speed of rotation of the engine corresponding to the critical speed of the hull; the system comprises a centrifugal supercharger, for supercharging said internal combustion engine, activated by speed multiplying means to be operating in a predetermined interval of speeds of the at least an internal combustion engine including said critical engine speed.

A multihull watercraft has at least three hulls extending longitudinally along the watercraft. The hulls at least partly define a port side tunnel and a starboard side tunnel therebetween. A port deflection device is configured to engage water in response to the watercraft leaning toward the port side when turning. The port deflection device is laterally aligned with the port side tunnel. A starboard deflection device is configured to engage water in response to the watercraft leaning toward the starboard side when turning. The starboard deflection device is laterally aligned with the starboard side tunnel. Each of the deflection devices includes an angled surface extending downwardly and rearwardly from an upper tunnel surface of a corresponding one of the tunnels. The angled surface is positioned to remain above a water line when the multihull watercraft is at rest on water.