The invention relates to a hydrofoil for a watercraft including a fuselage and two wings arranged on either side of the fuselage and designed to provide hydrodynamic lift to the hydrofoil when it is moving through the water. According to the invention, the two wings are rotatable relative to the fuselage between a deployed position when the hydrofoil is stationary, and a retracted position towards a rear part of the fuselage by the water pressure exerted on the wings when the hydrofoil is moving through the water.

The invention relates to a hydrofoil for a watercraft including a fuselage and two wings arranged on either side of the fuselage and designed to provide hydrodynamic lift to the hydrofoil when it is moving through the water. According to the invention, the two wings are rotatable relative to the fuselage between a deployed position when the hydrofoil is stationary, and a retracted position towards a rear part of the fuselage by the water pressure exerted on the wings when the hydrofoil is moving through the water.

A motorized hydrofoil apparatus may include a sailboard having a top surface and a bottom surface; a first hydrofoil assembly; a pivotable second hydrofoil attached to a second support unit; and a propulsion system. The hydrofoil apparatus may also include one or more sensing units disposed on predetermined locations on the first support unit to operatively communicate to the second hydrofoil to automatically generate corrective responses to various destabilizing hydrodynamic effects to stabilize the hydrofoil apparatus.

Disclosed is an apparatus, optionally mounted on a stand up paddle board, or surfboard, to lift the board above the water surface and support the board in a stable position above the water surface while a rider standing on the board and maintaining a speed in the water via paddling. In one embodiment, the apparatus includes a strut; a fuselage connected to said strut; a back foil portion connected to an aft end of said fuselage wherein the back foil portion includes two back wings extending outwardly from said aft end of said fuselage; and a forward foil portion connected to a fore end of said fuselage wherein the forward foil portion includes two front wings extending outwardly from said fore end of said fuselage and wherein the forward foil portion has a maximum thickness located at first distance from the fore edge of the forward foil portion.

A fin for a surfboard having a base and a tip and wherein the fin includes an integral tunnel which provides a tubular housing; an electric motor and associated propeller attached to the integral tunnel so as to be substantially enclosed therein; wherein the integral tunnel and propeller are both positioned so that there is a blade section above and below the integral tunnel which each have a height which is at least substantially 70% of the diameter of the integral tunnel, and wherein the motor and the propeller are positioned forward of a rear edge of the fin. Also provided is a power source to supply power to the electric motor and associated housing and mounting plate. The arrangement of the motor and propeller are located forward of a rear edge of the fin allows the original feel and maneuverability of a non-powered surfboard to be preserved.

Disclosed is a method for controlling a hydrofoil board powered by a motor driven propeller. The motor is controlled by a hand controller configured with user selectable operating pre-sets including a first operating pre-set, wherein the board is accelerated to a first speed which is less than that required for the board to hydrofoil, and a second operating pre-set, wherein the board is accelerated to a second speed sufficient for the board to hydrofoil. Alternatively, the operating pre-sets may limit the motor power. A system for operating a hydrofoil board is also disclosed, which includes a propulsion control unit comprising a propulsion source, and a hand controller configured to receive a first user input and a second user input and to transmit the user inputs to the propulsion control unit.

Disclosed is a method for controlling a hydrofoil board powered by a motor driven propeller. The motor is controlled by a hand controller configured with user selectable operating pre-sets including a first operating pre-set, wherein the board is accelerated to a first speed which is less than that required for the board to hydrofoil, and a second operating pre-set, wherein the board is accelerated to a second speed sufficient for the board to hydrofoil. Alternatively, the operating pre-sets may limit the motor power. A system for operating a hydrofoil board is also disclosed, which includes a propulsion control unit comprising a propulsion source, and a hand controller configured to receive a first user input and a second user input and to transmit the user inputs to the propulsion control unit.

A hydrofoil watercraft system comprising: a flotation device; a downward mast extending from a bottom surface of the flotation device; a fuselage, a foil wing extending from one first end of the fuselage; and a plurality of fins independently movable independent of one another, wherein at least two of the movable fins extend in opposite directions from one second end of the fuselage, where the movable fins are used for steering the watercraft. The system further includes a controller for receiving user input, wherein the controller drives the movable fins respectively based on the user input. One of the movable fins is driven by the controller to rotate along a first axis while another of the movable fins is driven by the controller to rotate along a second axis, wherein the first axis and the second axis are substantially symmetrical with respect to the fuselage.

A hydrofoil watercraft system comprising: a flotation device; a downward mast extending from a bottom surface of the flotation device; a fuselage, a foil wing extending from one first end of the fuselage; and a plurality of fins independently movable independent of one another, wherein at least two of the movable fins extend in opposite directions from one second end of the fuselage, where the movable fins are used for steering the watercraft. The system further includes a controller for receiving user input, wherein the controller drives the movable fins respectively based on the user input. One of the movable fins is driven by the controller to rotate along a first axis while another of the movable fins is driven by the controller to rotate along a second axis, wherein the first axis and the second axis are substantially symmetrical with respect to the fuselage.

A fin intended for a navigation object, in particular an inflatable or rigid-shell water board, including a wing which is able to move with respect to a fastening base about an axis of rotation between a first stabilizing position and a second folded position, and a rotation blocking element for blocking the wing in the folded position, the axis of rotation being borne by two hinge components, one of which is fastened to the wing and the other to the fastening base, the hinge component fastened to the wing also being able to move translationally with respect to the hinge component fastened to the fastening base in order to unblock the wing.