The present invention discloses a marine fishtail rudder, including a rudder blade, a first tail plate and a second tail plate. The rudder blade includes a first rudder surface and a second rudder surface. The first tail plate is hinged on the first rudder surface. The second tail plate is hinged on the second rudder surface. An electric motor is provided in the rudder blade. The electric motor is used to drive the first tail plate and the second tail plate to rotate, so that a trailing edge of the first tail plate and a trailing edge of the second tail plate are close to or away from a trailing edge of the rudder blade. The present invention discloses a marine fishtail rudder, wherein tail plates are respectively arranged on the two rudder surfaces of a rudder tail portion, and the tail plates are rotated by an electric motor. When steering, the tail plates are unfolded to form a rudder shape of a fishtail rudder to obtain a higher rudder effect. When sailing straight or reversing, the tail plates are closed to form a rudder shape of a streamlined rudder and reduce the resistance of the rudder.

A clamp assembly for connecting a rudder to an aquatic device having a body with a first end, a second end, a top and a bottom. A clamp having a screw connected to a pivot pin disposed within a clamp head is removably connected to the top of the body for selectively applying a clamping force on the body. The clamp handle in some bodies tapering to an end to allow placement within a retaining slot of a fin box.

One or more propulsion arrangements for water vessels, and in particular propulsion arrangements that include flanking rudders with bidirectional high-lift sections to improve performance, particularly in the reverse direction. The flanking rudders are positioned adjacent a propulsor for directing a slipstream flow when the vessel is travelling in the reverse direction. Each flanking rudder has an elongated profile extending from a first edge to a second edge, and in which each elongated profile has a first bulb portion, a convex middle portion, and a second bulb portion.

A device for improving steering in a watercraft. The device has a frame attached to two parallel blades. The device pivotally attaches to an attachment point on a steerable nozzle of a watercraft. Frame of device has two curved mount brackets that are substantially parallel to one another having a first end and second end. A mount bracket connector connects the two mount brackets at the first end. The mount bracket connector includes a down force regulator, that folds back over mount bracket connector. Each mount bracket terminates at its second end with a lift tab. Lift tabs direct water flow in a generally downward and outward direction as watercraft moves through the water. Each mount bracket bolts to a blade, thereby holding the two blades securely parallel to one another.

Disclosed is a propulsion unit for propelling a vessel. The propulsion unit comprises a main body configured to be arranged at a keel of the vessel and comprising a pivot point, a fin being movably arranged in relation to the main body, and an actuator assembly for generating a heave motion of the fin in relation to the main body. The actuator assembly comprises at least one actuator. The fin is connected to the pivot point, such that the fin is arranged to pivot around the pivot point when the at least one actuator generates the heave motion of the fin, thereby generating a pitch motion of the fin.

To provide a gate rudder capable of reducing energy consumption during a voyage of a ship.

A gate rudder including a pair of rudders including a left rudder and a right rudder disposed left and right, respectively, of a propeller at a stern, wherein each of the rudders includes a first rudder portion extending in a horizontal direction and a second rudder portion linearly extending in a vertical direction in rear view, wherein a rudder chord length of the second rudder portion in a front-rear direction is 40 to 100% of a diameter of the propeller, wherein the propeller is provided within a range of 15 to 65% of the rudder chord length from a front edge of the second rudder portion in side view, and wherein a rudder shaft that drives each of the rudders is provided at a position within a range of 30 to 50% of the rudder chord length from the front edge of the second rudder portion in side view.

A stand-alone modular removable rudder system for watercraft having a rudder comprising a steering handle coupled to a quick release mechanism adapted to releasably secure said steering handle to said watercraft in proximity to the operator, said system further comprising, a rudder mount adapted to be coupled to the rear of the watercraft by a quick release mechanism adapted to releasably secure said rudder mount to said watercraft, said rudder being carried by a rudder support pivotal about said rudder mount and cables operatively connecting said steering handle to said rudder mount whereby the steering handle can be operated to steer the rudder.

Embodiments of the present apparatus and method feature a permanently fixed canted keel. The apparatus and method feature tacking maneuvers which shift the sail element and reverse the direction of the hull form.

To easily grasp a relationship of parameter values which influence a log velocity of a ship, with the log velocity of the ship caused by the parameters, a ship characteristic estimating device is provided, which includes a data outputter configured to output a plurality of parameter data respectively including rotational speed data of a propeller of a ship, and wind velocity vector data of wind force that may act on the ship, and an estimator configured to receive the plurality of parameter data outputted from the data outputter, estimate values corresponding to the respective parameter data to be log velocity vectors of the ship, and output them as first output values. The rotational speed data are same as each other and the wind velocity vector data are different from each other.

A stand-alone modular removable rudder system for watercraft having a rudder comprising a steering handle coupled to a quick release mechanism adapted to releasably secure said steering handle to said watercraft in proximity to the operator, said system further comprising, a rudder mount adapted to be coupled to the rear of the watercraft by a quick release mechanism adapted to releasably secure said rudder mount to said watercraft, said rudder being carried by a rudder support pivotal about said rudder mount and cables operatively connecting said steering handle to said rudder mount whereby the steering handle can be operated to steer the rudder.