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 main body which comprises a first edge which is in contact with the board when the fin is secured to the board, a leading edge at the front and a trailing edge at the rear, a rear curve connecting the leading edge and the trailing edge, the trailing edge comprising a forwardmost front tip. The main body is extended rearwards by an arm which extends from a straight line which is perpendicular to the first edge and passes through the front tip of the trailing edge, as far as the rear curve, the arm having a length greater than approximately 8 cm.

A motorized board similar to a surf board is presented for use on a water surface. The motorized board includes a base board having a front end and a back end, a foot pedal on the base board, wherein the foot pedal is rotatable on the base board, and a motor coupled to the base board and connected to a propeller at the back end, the motor being controlled by the foot pedal. A user can stand on the board and turn the motor on with his foot, as well as control the speed with his foot to ride on a water surface with or without waves.

A foil assembly for a watercraft includes a base assembly, a fin rotatably connected to the base assembly such that the fin can rotate longitudinally, and a slider attachment configured to connect to a fin box of a watercraft wherein the base assembly is configured to be removably disposed within the slider attachment such that the base assembly and the fin can be removed and rotated laterally to a folded position and still be retained by the slider attachment to the fin box.

A sliding fin for a surfboard includes a base having a planar tab with an upper flange, a large fin piece having a first indentation, and a small fin piece for mating face-to-face with the large fin piece. The second fin piece has a second indentation that forms a channel that has a cross-sectional shape corresponding to a cross-sectional shape of the planar tab and upper flange, the channel being longer than the width of the planar tab, the small fin piece being translucent to enable the planar tab in the channel to be seen, the large and small fin pieces being slidable relative to the base on the planar tab.

The invention relates to floating devices for leisure and sports, and more particularly to water skis equipped with hydrofoils. The technical result is as follows: using claimed device, the user can travel not only on the water surface, but also on land without removing skis, as well as glide on hydrofoils or in a conventional water ski mode, and perform acrobatic maneuvers. The present device for the practice of a water sport comprises a pair of water skis. Each ski is comprised of a nose part and a tail part. The nose part is connected to the tail part by means of hinged fastenings. Water skis are equipped with a hydrofoil that can be flush with the bottom surface of the water ski.

The invention relates to floating devices for leisure and sports, and more particularly to water skis equipped with hydrofoils. The technical result is as follows: using claimed device, the user can travel not only on the water surface, but also on land without removing skis, as well as glide on hydrofoils or in a conventional water ski mode, and perform acrobatic maneuvers. The present device for the practice of a water sport comprises a pair of water skis. Each ski is comprised of a nose part and a tail part. The nose part is connected to the tail part by means of hinged fastenings. Water skis are equipped with a hydrofoil that can be flush with the bottom surface of the water ski.

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 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.