A passively controlled fluid foil has a span; and a rigid spar extending in the spanwise direction, a cellular material and a flexible outer surface defining a profile of the outer surface of the foil and encapsulating the cellular material and the spar.

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.

A hydrofoil and hydrofoil system for a surfboard is disclosed. The surfboard has a planar hull defined by a top surface, a bottom surface, a nose, a tail, and opposing side rails extending from the nose to the tail and that define a transition from the top surface to the bottom surface. The hydrofoil system includes one or more attachment mechanisms mounted with the planar hull at or proximate to at least one of the opposing side rails of the planar hull, each of the one or more attachment mechanisms comprising an attachment site oriented substantially laterally from the planar hull. The hydrofoil system further includes a hydrofoil configured to attach to the attachment site of one of the one or more attachment mechanisms, the hydrofoil further being configured to extend substantially laterally from the planar hull at or proximate to the at least one of the opposing side rails of the planar hull.

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.

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.

A personal watercraft includes a floatation member, a thrust assembly, a steering assembly, and a braking assembly. The assemblies may be actuated either mechanically or electrically. The thrust assembly is human powered, solar powered, or electric powered. The thrust, steering, and braking assemblies can be added after-market to an existing stand-up paddle board (SUP), or built into one or a plurality of SUPs during initial manufacturing. When the thrust assembly is human powered, it is leg or arm powered. When the thrust assembly is leg powered, the legs can move backward and forward in a sliding motion, up and down in a stomping fashion, or move in a loop trajectory. When the thrust assembly is arm powered, the arms can move forward/backward together or separately. The thrust assembly includes one or a plurality of paddles or flippers that are positioned to the side or under the SUP.

The present disclosure is directed to a personal watercraft, such as a standup paddleboard, provided with a viewing window that allows the user to view the underwater environment. The viewing window may be watertight and constructed from at least two durable, transparent panels. The area between panels may be sealed from air and water infiltration. A user may add waterproof lights to the bottom of the standup paddleboard in order to allow viewing of the underwater marine environment at night.

A paddle for stand-up paddle boards and other water craft includes a paddle blade at a lower end of the paddle shaft and a skeg/fin extending from the lower edge of the paddle blade. A method and system for transporting a user across water or other surfaces has a board or other water craft for the user to stand/sit upon and a paddle with the skeg/fin extending from the paddle blade.

Disclosed is a tool for watercraft fin insertion and removal. The tool includes: a first external elongated layer, a second external elongated layer, aligned with, and positioned at a substantially parallel plane to the plane of, the first external layer. An internal layer is positioned between, and stretches across a portion of the area of, the external layers. Upon positioning the tool such that the inner surfaces of the external layers are adjacent to the outer surfaces of the watercraft fin, a curved fin engagement elements on the edge of the internal layer, complements at least a portion of the leading edge or the trailing edge of the watercraft fin.

A retractable fin watercraft accessory that provides steering and tracking for a watercraft such as stand-up paddle boards. The retractable fin system gently retracts as it comes in contact with subsurface objects such as rocks, logs and such, allowing the watercraft to freely pass over the object. The system includes a sloped leading edge which can more easily slide past an obstacle. The retractable fin system simply attaches to the watercraft's existing fin mounting box and can be removed from the watercraft without altering the original state of the watercraft prior to being attached. No drilling, welding, gluing or other such custom fabrication is required. The system allows for quick interchangeability between the retractable fin and various rigid style fins, depending on the user's preferences.