Abstract: A watercraft having a propulsion mechanism extending through an opening in the bottom of the watercraft having a propulsion mechanism adapted to be inserted in an opening in the bottom of a watercraft comprising a pair of pedals each coupled to a flexible fin extending below the water line, the pair of fins oscillate through an arcuate path on a horizontal axis to propel the watercraft. The horizontal axis is preferably continuously rotatable in either direction through 360° on a vertical axis disposed at a substantially right angle to the longitudinal axis of the watercraft to propel the watercraft in any direction.

Abstract: A towable recreational craft having a body member for accommodating one or more riders in a prone position is disclosed. One or more stabilizing members are movably coupled to and extend away from an aft portion of the body member. Each stabilizing member includes a foot-accommodating portion spaced apart from the body member, wherein the stabilizing member is movable between a position extending away from the aft portion of the body member and a position adjacent a lateral portion thereof to provide greater stability as the craft is towed.

Abstract: An electrical linear motor for propelling a marine vessel through a liquid medium, comprises a housing secured to the marine vessel and submerged in the liquid medium, an insert within the housing and having at least two electrical coil windings disposed on internal walls of the insert; a thruster subassembly moves between the internal walls of the insert, the thruster subassembly having a front cover, an internal channel with check valve and at least two sets of permanent magnets attached to the thruster subassembly and maintained in sufficiently close proximity to the electrical coil windings so that an electromagnetic field created by a controlled energizing of the electrical coil windings interacts with a magnetic field from the permanent magnets to provide a resulting linear force, which causes a reciprocating linear motion of the thruster subassembly, wherein the check valve is in an open position during a back stroke of the thruster subassembly so that the liquid medium flows freely through the thruste

Abstract: An electrical linear motor for propelling a marine vessel comprises a thruster assembly disposed within a guide tube. Permanent magnets are attached to the thruster assembly and placed in close proximity to electrical coil windings, which are positioned outside of and parallel to the guide tube. Electrical current energizing the coil windings creates an electromagnetic field, which interacts with the magnetic field of the magnets to cause reciprocating linear motion of the thruster assembly with the guide tube. During the non-propelling back stroke, a check valve on the thruster assembly is in open position to allow free passage of water. The check valve is moved to a closed position during the working stroke of the thruster assembly, allowing the thruster assembly to propel the marine vessel.

Abstract: A manually-operable reciprocating rowing system having a reversible oar for forward or reverse propulsion. The oar has a plurality of pivoting blades mounted in a housing and movable between open and closed positions with each stroke of the oar. In the open position, the blades are positioned to allow water passage through the housing, while in the closed position, the blades are positioned to obstruct water passage through the housing. Gates are provided for stopping the pivoting movement of the blade at the blade housing. A reversing mechanism selectively pivots the gates to allow the blades to pass from one side to an opposite side of the housing, thereby allowing propulsion in a reversed direction.

Abstract: A rowing surf board includes a board having two through holes defined through the board and tow oars are respectively pivotably engaged with the through holes. Each oar has a blade portion which is pivotably connected to a distal end beneath the board such that the blade portion is pivoted to reduce a contact area against water when the blade portion is moved forward.

Abstract: A propeller guard assembly for watercraft that, in cooperation with a rotating propeller, creates a substantial increase in propulsive thrust and provides improved all around shielding of the latest state of the art propeller configurations such as wider propeller blades and contra rotating dual propeller systems.

Abstract: A method for propulsion of water-going vessels (1) comprising a plate (9), which is located in the water (2) and extends across a desired direction of motion for the vessel (1), where the plate (9) is moved from a first position (P1) to a second position (P2) and back. Under the influence of a motive force the extent of which varies sinusoidally, the plate (9) is brought into translatory and rectilinear oscillation about a neutral position (N2) between the first and the second position (P1 and P2 respectively), the neutral position (N2) being determined by a static equilibrium between spring forces influencing the plate (9). The plate (9) is controlled in such a manner that its plate plane extends perpendicularly to the vessel's (1) direction of motion, and a greater resistance is exerted by the plate (9) against the water when it is moved opposite to the vessel's desired direction of motion than when it is moved in this direction. A device for performing the method.

Abstract: A propeller guard assembly for water craft that, in cooperation with a rotating propeller, creates a substantial increase in propulsive thrust and provides improved all around shielding of the latest state of the art propeller configurations. The increase in propulsive thrust of the propeller guard assembly of the invention is created primarily by the angle of the attack and hydrofoil cross section of the four guard rings or cowlings of the device. A secondary reason for the increase in propulsive thrust of the propeller guard assembly of the invention resides in the fact that the thrust realized is equal to the ratio between the effective projected propeller area and the area of trailing edges of the large primary and secondary guard rings which decreases the tendency of the propeller race to spread, particularly at high propeller slip during acceleration and take off.

Abstract: A new leg-powered boat for propelling through water by using one's legs. The inventive device includes a boat portion defined by an open upper end, a closed lower end, forward and rearward ends, and opposed side walls extending between the forward and rearward ends. The closed lower end has an interior surface. The interior surface has a rail that extends a portion of a length of the interior surface. The rail has a channel formed therein extending a length of the rail. A seat portion is slidably coupled with respect to the boat portion. The seat portion has a lower portion and an upper portion. The lower portion has a bracket that extends through the channel. A pulley system has a plurality of pulleys and a cable that extends around the pulleys. The cable is coupled to the bracket of the seat portion. The closed lower end of the boat portion has a track that extends therein from a lower surface of the closed lower end.

Abstract: The equipment includes a device for floating on the surface of a body of water and for supporting at least one user, and footwear worn by the user for propelling the device through the water. The device for floating includes at least two spaced, parallel, side-by-side pontoons and a frame connected to the pontoons and extending above the space between the pontoons for supporting the user in the space between the pontoons. The footwear includes a foot receiving portion having a foot receiving surface and a second surface opposite to the foot receiving surface and fins extending downwardly from the second surface.

Abstract: A pulsating impeller system is provided for moving a body through a fluid medium. The pulsating impeller includes an enclosure mounted on a vessel or other body. The enclosure is provided with an inlet-outlet aperture to facilitate the flow of the fluid medium into and out of the enclosure. An expansible membrane is positioned in the enclosure. The volume of the expansible membrane is inflated and deflated on a regular cycle by a compressed air or other similar system in the vessel. When the enclosure is placed in a fluid, such as water, and the expansible membrane inside the enclosure is inflated, the volume of the membrane is increased, which results in the water being forced through the outlet hole in the enclosure to propel the vessel. This force will generate a reactive force which will thrust the enclosure and vessel in the opposite direction. The vessel may be provided with a plurality of enclosures, and each enclosure may have one or more expansible membranes.

Abstract: An aquatic ski for human propulsion generated by deambulatory action having a floatable hull and a propulsive oscillating fin assembly. The fin assembly includes a foot seat pivotally connected to the hull and a movable fin in articulated and cooperative connection with the foot seat. The movable fin has a plurality of free oscillating vanes pivotally connected between a pair of parallel arms. The oscillating vanes are movable between a position aligned with the arms and a position transverse to the arms. The hull has a forward portion and a rearward portion pivotally connecting together. The hull includes flotation chambers forward and rearward of the foot seat.

Abstract: The device is an alternative to the conventional paddle or oars, and comprises a collapsible scoop and a handle-shaft. The scoop has top and bottom panels 14,16, hinged together along one edge 18, and side-panels. The side-panels 20 are foldable, and allow the scoop to open and close. When the handle is pushed, the scoop opens out by the action of hydrodynamic forces; when pulled, the scoop collapses. The scoop is made from a one-piece blank cut from stiff plastic sheet. The hinges are formed by locally creasing the plastic material.

Abstract: In exercise apparatus for underwater use including an apparatus frame, and movable members mounted on the frame to be moved by a user of the apparatus, flap members, e.g., flat plates, are mounted on the movable members for movement therewith within the surrounding water. The water resists movement of the flap members, hence provides resistance to movement of the members moved by the user. Disclosed are apparatus which, in use, simulate the movements of a cross-country skier, an ice-skating speed racer, and a rower of a row boat. Stop are also disclosed for selectively varying the resistance to movement provided by the flap members in response to the direction of movement of the movable members.

Abstract: A swimming frame for competition in swimming, swimming instruction, muscle strengthening, and entertainment in the water comprises a pair of floats (1), a clamping unit (2, 3), and a paddle unit (4, 5, 6). It might be used by everyone regardless of the ability to swim. The paddle unit might by modified giving an additional possibility to practice butterfly-like and crawl-like style of swimming. A swimmer being clamped between rigid (2) and flexible (3) portion of the clamping unit is producing the push-pull movements of the paddle unit. When he pushes the unit, the paddle (4) is rotated up to horizontal position by the water pressure against its front. When he pulls the unit, the paddle is rotated up to vertical position by water pressure against its back. Because of the difference in the paddle hydroresistance between push and pull movements the swimming frame will be propelled by the swimmer.

Abstract: A water ski also adapted for walking on land is disclosed. The ski comprises a pontoon of generally streamlined shape, formed of a lightweight rigid material, and a plurality of spaced cups of a flexible material attached to the lower surface of the pontoon, each of the cups being open at the rear end thereof to form a pocket to receive water and provide water resistance against the backward movement of the pontoon, the cups closing against the lower surface of the ponton by the action of the water during the forward motion of the pontoon to reduce drag. According to one embodiment, a plurality of fins are disposed longitudinally along its lower front portion of the pontoon and extending below the cups in the closed position thereof, and an additional fin or runner is disposed longitudinally along the lower rear portion of the pontoon and extending below the cups in the closed position thereof.

Abstract: A supplemental propulsion device for a sailboat or sailboard type water craft including a pivotal centerboard. A pair of propulsion wings that are vertically hinged to one-another and mounted to the lower portion of the leading edge of the centerboard of the craft. Upon the application to the centerboard of a reciprocating pumping action each propulsion wing moves inwardly to a retracted position adjacent the centerboard during forward movement of the lower portion of the centerboard and moves outwardly to an extended position removed from the centerboard during rearward movement of the lower portion of the centerboard. Cables connect the free edge of each of the propulsion wings to the trailing edge of the centerboard to stop the outwardly movement of the wings at a point no more than 90.degree.

Abstract: The invention is to provide a kind of skiing shoes especially referring to a kind of water skiing buoyant shoes. The distinctive features are on a pair of skiing shoe base members buoyant on water surface, we can walk freely and it becomes an additional updated, unique, novel and excitative recreation of water activities. Besides, the invention can be converted to have the function of a sailboat for the pleasure of sailing. The advantages of the invention are high safety, easy to be assemblied, convenient to walk on water surface and buoyancy to be free from sinking. We can enjoy not only the pleasure of water activity but the sceneries around as well as underwater.

Abstract: This device is for aiding a swimmer to obtain more thrust when swimming underwater. Primarily, it consists of a pair of poles secured to a harness, which is worn by the user. It also consists of a plurality of pivotal fins secured to the harness, for increasing the speed of the user, who moves the device by a pair of handle grips secured to the poles.

Abstract: A rocking member is installed in a recess in a device floating on water by a pivot shaft extending approximately parallel to the surface of the water. Such rocking member has a bottom impelling surface displaceable upward and downward by swinging of the rocking member. A plurality of water-trapping wedge-shaped fins, extending approximately parallel to the pivot shaft and spaced apart longitudinally of the device, project downward from the rocking member impelling surface.

Abstract: A buoyant craft, such as a boat or raft, propelled by a water jet thrust of high efficiency. Such thrust is provided by a wedge shaped chamber, such as one including a substantially flat plate pivotally mounted forwardly and on the underside of the craft and having two vertical sides. Pedals are provided on an extension of the flat plate. A modification involves the use of two separate wedge shaped jet thrust chambers with a common central wall to permit better steering. Still another modification involves the use of a wedge shaped chamber made of rubber or other flexible elastomer which is squeezed by pivotal movement of the pedal-operated flat plate to effect jet propulsion.