Abstract: A novel gas propulsion device comprises one or more high-frequency linear actuators (such as a voice coil linear actuator or a piezoelectric linear actuator) attached to one or more gas propulsion elements having a concave internal surface facing a first side thereof. Linear actuators operate to cause reciprocal movements of each gas propulsion element at a sufficient speed, such as a subsonic or supersonic speed, and suitable amplitude to form a high gas pressure zone on the first side of the gas propulsion element and a low gas pressure zone on the second side thereof. The gas pressure differential in turn causes propulsion of gas away from the device along the longitudinal axis or to the side of it if the gas propulsion element is tilted. The invention may be used as a main or secondary thrust engine for an aircraft.

Abstract: The mechanical oar system is a manually powered propulsion system for a vessel. The vessel is a personal watercraft. The mechanical oar system is configured for use with a person. The mechanical oar system is powered by the person. The mechanical oar system comprises a plurality of drive mechanisms and a vessel. The plurality of drive mechanisms are integrated into the vessel. Each of the plurality of drive mechanisms is manually powered. Each of the plurality of drive mechanisms comprises a mechanism that moves an oar structure (referred to in this disclosure as a blade). The oar structure propels the vessel in a desired direction. Each of the plurality of drive mechanisms is oriented relative to the vessel such that the direction of the propulsive forces can be adjusted by the person.

Abstract: There is disclosed a watercraft paddle apparatus operable by a user's legs and feet. In an embodiment, the watercraft paddle apparatus comprises a pair of rails positioned side-by-side and mountable to a watercraft, each rail configured to slidably receive a pedal mechanism adapted to slide back and forth along each rail. Each pedal mechanism includes a downwardly extendable paddle adapted to engage a water surface on which the watercraft is floating during a backward stride and to lift from the water surface on a forward stride, whereby a user can operate the pedal mechanism in each rail using an alternating walking or skiing motion. In an embodiment, each pedal mechanism is supported laterally by a front axle with a pair of wheels on either end of the front axle engaging the parallel rails. In another embodiment, each pedal mechanism is attached.

Abstract: The present invention relates to a flexible propeller that has the feature of generating propulsive force in only one direction, irrespective of the direction of rotation. The flexible propeller may be used in a mechanism similar to a sterndrive, being actuated by two cables and that are wound around a threaded spindle on the sterndrive shaft, one clockwise and the other anticlockwise, and capable of being actuated alternately longitudinally, causing the flexible propeller to rotate in alternate directions, first in one direction and then in the other. The sterndrive in turn may be used in compact structures that can be fitted to catamarans, kayaks or other types of small vessels, without the need for major alterations to the original vessel.

Abstract: An oar or paddle for moving forward and backward any kind of vessel through the water comprising two parallel lattices fixed at a given distance from each other and a frame moving between lattices. The frame has a multitude of parallel grooves of circular cross-section which pivotally support a multitude of plates. The plates are located axially of the grooves by the portion of the plates disposed within the groove. The grooves have a peripheral extent which permits the plates to rotate. The frame is connected with vessel's mode of movement backward or forward controller. Lattices are connected with vessel's engine.

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 small self-propelled watercraft having a main hull and an outrigger hull that is powered by a fin like oar arrangement. The main hull seats the rider and provides the substantial portion of the buoyancy for the watercraft. The fin like oar arrangement includes a blade type fin that is supported for pivotal movement at the end of the oar and the degree of pivotal movement can be adjusted from the handle end of the oar. In addition, the fin like blade is supported for movement between forward and reverse thrust positions and this movement is also controlled at the handle of the oar.

Abstract: A recreational water craft is propelled by an individual using cross country skiing action. The weight of the operator is supported on a platform between two parallel floats thus providing a stable craft. The water craft comprises two longitudinal floats with a connecting frame, a first guide rail is mounted on the connecting frame having a first foot supporting trolley constrained to move backwards and forwards on the first guide rail, a second guide rail substantially parallel to the first guide rail mounted on the connecting frame, having a second foot supporting trolley constrained to move backwards and forwards on the second guide rail, a propulsion arrangement for moving the craft through the water when the first trolley or second trolley are moved backwards and forwards on the first or second guide rails, and a steering arrangement to direct direction of movement of the craft through the water.

Abstract: A boat propulsion apparatus having a thrust blade mounted for swinging movement about a generally horizontal axis lengthwise of the boat and for turning movement about an upright axis, and a swash plate drive for simultaneously swinging the blade in a direction crosswise of the boat and for angularly oscillating the blade about its upright axis to sinusoidally vary the pitch of the blade as the blade is swung crosswise of the boat. Provision is made for reversing the direction of angular oscillation of the blade about the upright blade axis relative to the direction of the swinging movement of the blade to enable forward and reverse drive. A variable angle swash plate drive is provided to vary the mechanical advantage of the drive.