Abstract: Fluke drive system for a vessel (100), comprising a pivot element (114) having a forward end and an aft end, which pivot element (114) is pivotally connected at the forward end to a hull (101) of the vessel (100) and which pivot element (114) is connected at the aft end to a flexible fluke (125); a driving mechanism having a drive point (120), which driving mechanism is arranged to impart a reciprocal or rotary movement to the drive point (120); and a drive rod (121) having a first end and a second end, which drive rod (121) is connected at the first end to the drive point (120) and at the second end to the pivot element (114), which second end is connected to the pivot element (114) at a point (122) along the pivot element (114) between said forward and aft ends.

Abstract: A propulsion device and a watercraft including the propulsion device. The propulsion device comprises a flexible fluke that is pivotable about a horizontal axis, for propelling a floating watercraft. The propulsion device is adapted for connection to an output drive shaft that transmits rotary motion. The propulsion device comprises a fluke oscillation drive having gear reduction of the rotary motion transmitted by the shaft and a mechanism for converting the rotary motion transmitted by the shaft to oscillatory motion of the fluke.

Abstract: A watercraft propulsion device 10 has a linkage comprising a vertical drive link (20), a support link (12), an upper control link (50) having a forwardly extended handle bar (52), and a lower propulsion link (30) having a horizontal propulsion fin (32) backwardly extended therefrom. The control and propulsion links (50, 30) are interconnected by said drive link (20), which is capable of conveying propulsive oscillatory motion to the propulsion link (30) by means of a linear power actuator (90), and by the support link (12), which is pivotally connected a transom bracket (60) about a substantially vertical axis.

Abstract: A propulsion device is disclosed for propelling a floating watercraft. In at least one embodiment, the propulsion device includes a flexible fluke that is pivotal about a substantially horizontal fluke pivot axis, and at least one device for transmitting an oscillatory motion about the fluke pivot axis to the fluke. The propulsion device may be reconfigured between two or more modes or combinations of modes, for example: a manual power mode, in which a hand-lever is mechanically engaged with the fluke for transmitting an oscillatory, propulsive motion to the fluke by way of a reciprocating movement of the hand-lever; a motor-powered mode, in which a motor is mechanically engaged with the fluke, and the motion of the hand-lever is isolated from any propulsive motion of the fluke about the fluke pivot axis; a forward mode, in which a main portion of the fluke extends astern of the pivot axis; and a reverse mode, in which a main portion of the fluke extends afore of the fluke pivot axis.

Abstract: A watercraft propulsion device 10 has a linkage comprising a vertical drive link (20), a support link (12), an upper control link (50) having a forwardly extended handle bar (52), and a lower propulsion link (30) having a horizontal propulsion fin (32) backwardly extended therefrom. The control and propulsion links (50, 30) are interconnected by said drive link (20), which is capable of conveying propulsive oscillatory motion to the propulsion link (30) by means of a linear power actuator (90), and by the support link (12), which is pivotally connected a transom bracket (60) about a substantially vertical axis.