A training hydrofoil system for connection with a watercraft comprises a first wing including at least one adjustable surface and a second wing including at least one adjustable portion. The system further includes a fuselage extending longitudinally and the first and second wing connected to the fuselage and extending latitudinally relative to the fuselage, the fuselage including an attachment feature for attaching to the watercraft. The system further includes an electronic control unit capable of actuating at least one of the adjustable surface and adjustable portion to modify a course of the watercraft, and a power source. Both the power source and the electronic control unit are positioned in the fuselage.

A stern rudder fixing structure for fixedly connecting a stern rudder body to a stern rudder base is disclosed. The stern rudder fixing structure comprises a T-shaped bolt, a nut and a rotary rod, wherein the stern rudder body is detachably connected to the stern rudder base. The stern rudder comprises a stern rudder body, a stern rudder base and a fixing structure. The stern rudder and a paddle board provided by the disclosure are matched with a first insertion hole and a second insertion hole of the stern rudder base through the fixing structure, so that the stern rudder body and the stern rudder base are quickly assembled and dissembled in a time-saving and error-saving mode.

A stern rudder fixing structure for fixedly connecting a stern rudder body to a stern rudder base is disclosed. The stern rudder fixing structure comprises a T-shaped bolt, a nut and a rotary rod, wherein the stern rudder body is detachably connected to the stern rudder base. The stern rudder comprises a stern rudder body, a stern rudder base and a fixing structure. The stern rudder and a paddle board provided by the disclosure are matched with a first insertion hole and a second insertion hole of the stern rudder base through the fixing structure, so that the stern rudder body and the stern rudder base are quickly assembled and dissembled in a time-saving and error-saving mode.

A water ski fin comprising a planar body and a plurality of chevrons. The planar body may have a top end, a convex leading edge, and a trailing edge. The mounting elements on the top end may mount the fin on a tail of a water ski. A bottom may connect the leading edge to the trailing edge. A plurality of chevrons may have alternating crests and troughs positioned in the trailing edge.

A water ski fin comprising a planar body and a plurality of chevrons. The planar body may have a top end, a convex leading edge, and a trailing edge. The mounting elements on the top end may mount the fin on a tail of a water ski. A bottom may connect the leading edge to the trailing edge. A plurality of chevrons may have alternating crests and troughs positioned in the trailing edge.

A hydrofoiling watercraft including a board for supporting a user includes a plurality of masts extending downwardly to connect one or more hydrofoil wings to the board. Examples of the watercraft include a fuselage mounted to each mast wherein a forward portion of each fuselage extends toward a direction of travel for the watercraft. A hydrofoil wing is mounted to the forward portion of each fuselage. A tail wing may be mounted to a rearward portion of the respective fuselages.

A hydrofoiling watercraft including a board for supporting a user includes a plurality of masts extending downwardly to connect one or more hydrofoil wings to the board. Examples of the watercraft include a fuselage mounted to each mast wherein a forward portion of each fuselage extends toward a direction of travel for the watercraft. A hydrofoil wing is mounted to the forward portion of each fuselage. A tail wing may be mounted to a rearward portion of the respective fuselages.

A fin for use on a surfboard, the fin comprising: a leading edge, a trailing edge, and a base, the base comprising at least one mount for mounting the fin onto a surfboard; a first and a second outer fin surface which meet along the leading edge and the trailing edge and abut the base; and a first ridge protruding laterally from the first outer fin surface, and/or a second ridge protruding laterally from the second outer fin surface; wherein the shape and configuration of the fin creates an area of lower water pressure around and in front of the fin, as well as disrupting and/or reducing the size of trailing vortices, resulting in additional forward thrust for the board on which the fin is mounted.

A fin for use on a surfboard, the fin comprising: a leading edge, a trailing edge, and a base, the base comprising at least one mount for mounting the fin onto a surfboard; a first and a second outer fin surface which meet along the leading edge and the trailing edge and abut the base; and a first ridge protruding laterally from the first outer fin surface, and/or a second ridge protruding laterally from the second outer fin surface; wherein the shape and configuration of the fin creates an area of lower water pressure around and in front of the fin, as well as disrupting and/or reducing the size of trailing vortices, resulting in additional forward thrust for the board on which the fin is mounted.

A watercraft fin that dynamically keep a neutral alignment within the range of angles a user chooses to have and/or change in respond to the flow conditions so reducing drag. Hence, this invention is such to enable a fin to rotate within a range of angles via a rotary bearing and bearing housing which are to receive a fin having a journal base. The housing is to be fitted to a watercraft such as a surfboard, the housing having a changeable circular keyway to loosely receive a shear key at the underside of the journal base as to allow free circular motion of the shear key and correspondingly the journal base and the fin within the limits of the selected circular length of the keyway. In one form the fin is fitted with a root portion adapted to be inserted into a receiving portion extending radially in the journal base and trapped within the bore of the bearing.