A system for retracting a foil of a watercraft in the event of an impact has a strut extending from a watercraft, the strut has a pivot at one end that connects the strut to the watercraft and allows the strut to articulate around the pivot, a foil attached at a second end of the strut, wherein the foil has sufficient surface area configured to generate positive lift when the watercraft is traveling over water; and a retraction system including a mechanical fuse connected to the strut, the mechanical fuse holds the strut stationary and is subject to forces from the strut when the strut travels through water, the retraction system allows retraction of the strut around the pivot when the strut experiences a force greater than a predetermined limit, and the foil is configured to articulate on the strut to maintain positive lift orientation as the strut is retracting.

Embodiments described herein relate generally to a sailing vessel that can substantially obviate the heeling problem experienced by classical sailboats. During navigation, the sailing vessel is driven forward by an aerodynamic force exerted by wind on the sail, and balanced by a hydrodynamic force exerted by water on a float on the stern of the sailing vessel, the aerodynamic force and the hydrodynamic force being parallel or substantially parallel to a longitudinal axis of the sailing vessel.

A method and a controller unit for controlling motion of a watercraft with a hydrofoil) obtains information indicating shape of water surface in front of the hydrofoil. The controller unit further predicts wave acceleration of the watercraft using a neural network. Furthermore, the controller unit determines a target route and corresponding total acceleration of the watercraft under a set of constraints. The total acceleration is minimized when the watercraft travels according to the target route. The set of constraints includes: a first constraint that the hydrofoil stays within an interval relative to the water surface, and a second constraint relating to magnitude of acceleration derived from maximum AoA and the predicted wave acceleration. The controller unit calculates an AoA for the target route. Next, the controller unit sends a signal for adjusting the hydrofoil according to the AoA.

The present disclosure generally pertains to a lateral displacement surf system and methods of laterally displacing a watercraft to generate wake. The lateral displacement system includes at least one pair of foils configured to be extended from a hull on a first side of the watercraft at a level of approximately the waterline. Upon forward movement of the watercraft with extended foils, the watercraft is rotated about its vertical axis toward the first side and generates waves sufficient for the conduction watersport activities on a second side of the watercraft. In some instances, foils are built into the hull and extended from this position, while in other instances the foils are attached to the hull using attachment structures. Rotation of the foils about an axis of rotation approximately perpendicular to a longitudinal axis of the watercraft alters the angle of attack of the foils relative to the waterline.

A wing, a method of controlling lift on a wing, and a system to produce lift on a wing are provided. The wing may include a fore-element, an aft-element, a pivotable linkage that operatively connects the aft-element leading edge to the fore-element trailing edge in a span-wise direction, and an actuator. The actuator may deflect the aft-element through a predetermined deflection angle about the pivotable linkage relative to the fore-element within less than or equal to two convective periods. The method may include deflecting a span-wise flap through the deflection angle in less than or equal to two convective periods to produce high lift. The system may include a sensor to detect an input and a controller to deflect the span-wise flap of the wing by the deflection angle in not more than two convective periods based on the received input signal.

A wing, a method of controlling lift on a wing, and a system to produce lift on a wing are provided. The wing may include a fore-element, an aft-element, a pivotable linkage that operatively connects the aft-element leading edge to the fore-element trailing edge in a span-wise direction, and an actuator. The actuator may deflect the aft-element through a predetermined deflection angle about the pivotable linkage relative to the fore-element within less than or equal to two convective periods. The method may include deflecting a span-wise flap through the deflection angle in less than or equal to two convective periods to produce high lift. The system may include a sensor to detect an input and a controller to deflect the span-wise flap of the wing by the deflection angle in not more than two convective periods based on the received input signal.

A foil displacement system includes one or more foils that can be deployed and stowed. When deployed, each foil can exert downforce or uplift depending on its orientation. For example, each foil may be positioned to have an angle of attack that creates a downward force effectively transmitted to the hull to pull the hull deeper within the water to, for example, create a larger wake. Use of the foil displacement system can enhance or replace the use of a ballast tank system, can be integrated into a new boat or retrofitted to existing boats, can be electronically or manually positioned, can enhance activities such as wake surfing, wake boarding, water skiing or other similar or related water sports.

A sailing boat has an auxiliary hydrodynamic surface carried by a main boom connected in an oscillating way to a deck of the boat, about an axis of articulation parallel to the longitudinal direction of the boat. A drive system lowers the main boom on one side or the other of the boat in such a way that the hydrodynamic surface is selectively lowerable in a first operative position on one side of the boat to be put into the water on one side of the boat or in a second operative position on the other side of the boat to be put into the water on the other side of the boat. The boom is sized so that, when the hydrodynamic surface is located in one of its two operative positions on one side or the other of the boat, it is set at a lateral distance from the boat.

An example wing-in-ground effect vehicle includes (i) a main wing having main wing control surfaces; (ii) a tail having tail control surfaces; (iii) a blown-wing propulsion system arranged along the main wing or the tail; (iv) a retractable hydrofoil configured to operate in: (a) an extended configuration in which the retractable hydrofoil extends below a hull of the vehicle for submersion below a water surface and (b) a retracted configuration in which the retractable hydrofoil is retracted at least partially into the hull of the vehicle; and (v) a control system configured to maneuver the vehicle by (i) causing a change in orientation of the retractable hydrofoil when the retractable hydrofoil is operating in the extended configuration, and (ii) causing a change in orientation of the main wing control surfaces and tail control surfaces when the retractable hydrofoil is operating in the retracted configuration.

An example wing-in-ground effect vehicle includes (i) a main wing having main wing control surfaces; (ii) a tail having tail control surfaces; (iii) a blown-wing propulsion system arranged along the main wing or the tail; (iv) a retractable hydrofoil configured to operate in: (a) an extended configuration in which the retractable hydrofoil extends below a hull of the vehicle for submersion below a water surface and (b) a retracted configuration in which the retractable hydrofoil is retracted at least partially into the hull of the vehicle; and (v) a control system configured to maneuver the vehicle by (i) causing a change in orientation of the retractable hydrofoil when the retractable hydrofoil is operating in the extended configuration, and (ii) causing a change in orientation of the main wing control surfaces and tail control surfaces when the retractable hydrofoil is operating in the retracted configuration.