In order to create an improved arrangement to reduce the propulsion-power requirement of a twin-screw ship comprising a first propeller and a second propeller and a first guiding device and a second guiding device, wherein, in the forward direction of the watercraft, the first guiding device is arranged in front of the first propeller, and the second guiding device is arranged in front of the second propeller, wherein the first propeller and the second propeller are attached to a first propeller shaft and to a second propeller shaft, and wherein the first propeller shaft defines a first propeller axis and the second propeller shaft defines a second propeller axis, the first guiding device and the second guiding device each comprise at least one fin, which extends from the propeller axes, wherein the fin of the first guiding device and of the second guiding device extend outwardly to the sides of the watercraft respectively.

An improvement to a conventional surfboard includes an impeller and an electric motor contained primarily within the body of the surfboard, whereby performance of the surfboard is substantially unaffected by the presence of the impeller and the electric motor. The electric motor is operatively connected to the impeller for providing a forward thrust of the surfboard. The improvement to the conventional surfboard also includes a throttle for selective control of the electric motor for operating the impeller to provide a forward thrust of the surfboard, the throttle being configured for use by a surfer lying in a prone position on the smooth top surface of the body of the surfboard. An extent of the surfer's energy that otherwise would be expended during paddling can be preserved for riding waves by using the impeller to provide the forward thrust during paddling.

A waterfowl decoy deployment system includes a hub subsystem including a casing, a plurality of arms extending radially outward from the casing, and a plurality of waterfowl decoys. At least one waterfowl decoy of the plurality of waterfowl decoys is coupled to each arm of the plurality of arms. The waterfowl decoy deployment system also includes a thrust bar system coupled to the casing and positioned below the plurality of arms and the plurality of waterfowl decoys. The thrust bar system includes a thrust bar coupled to the casing and a plurality of thrust devices coupled to the thrust bar. The plurality of thrust devices are configured to rotate the thrust bar about an axis to induce a substantially circular motion to the casing, the plurality of arms, and the plurality of waterfowl decoys.

An improvement to a conventional surfboard includes an impeller and an electric motor contained primarily within the body of the surfboard, whereby performance of the surfboard is substantially unaffected by the presence of the impeller and the electric motor. The electric motor is operatively connected to the impeller for providing a forward thrust of the surfboard. The improvement to the conventional surfboard also includes a throttle for selective control of the electric motor for operating the impeller to provide a forward thrust of the surfboard, the throttle being configured for use by a surfer lying in a prone position on the smooth top surface of the body of the surfboard. An extent of the surfer's energy that otherwise would be expended during paddling can be preserved for riding waves by using the impeller to provide the forward thrust during paddling.

[Problems]

To reduce the fuel consumption without impairing operational safety of the ship

[Solution to Problem]

A ship 10 configured to obtain propelling force by driving a main propeller 11 with a main engine 12 is provided with an additional propeller 20 and a driving unit therefore. The additional propeller 20 is disposed at a ship bottom or at a rising section of the ship bottom, in a position different from the main propeller 11. Further, the output of the driving unit of the additional propeller 20 is 25% or less than the output of the driving unit of the main engine, and the operating condition can be selectable between regular operating condition in which propelling force is obtained by driving the main propeller 11 and die other operating condition in that propelling force is obtained by driving the additional propeller 20.

[Problems]

To reduce the fuel consumption without impairing operational safety of the ship

[Solution to Problem]

A ship 10 configured to obtain propelling force by driving a main propeller 11 with a main engine 12 is provided with an additional propeller 20 and a driving unit therefore. The additional propeller 20 is disposed at a ship bottom or at a rising section of the ship bottom, in a position different from the main propeller 11. Further, the output of the driving unit of the additional propeller 20 is 25% or less than the output of the driving unit of the main engine, and the operating condition can be selectable between regular operating condition in which propelling force is obtained by driving the main propeller 11 and die other operating condition in that propelling force is obtained by driving the additional propeller 20.

The present disclosure relates to a propulsion control system (30) for controlling a marine vessel (10) comprising at least four propulsion units (20, 22, 24, 26). The marine vessel (10) comprises a longitudinal centre line (L) and a transversal line (T). The transversal line (T) extends in a direction perpendicular to the longitudinal centre line (L) and also extends through the steering axis of the aftmost of the propulsion units. The marine vessel (10) comprises four quadrants (I, II, III, IV) defined by the longitudinal centre line (L) and the transversal line (T) wherein a first (I) and a second (II) quadrant are located on the same side of said longitudinal centre line (L). When a combined sway and yaw motion is desired, the thrust of one propulsion unit is directed towards the second (I) quadrant, and the thrust of the other propulsion units is directed towards the first (II) quadrant.

The present disclosure relates to a propulsion control system (30) for controlling a marine vessel (10) comprising at least four propulsion units (20, 22, 24, 26). The marine vessel (10) comprises a longitudinal centre line (L) and a transversal line (T). The transversal line (T) extends in a direction perpendicular to the longitudinal centre line (L) and also extends through the steering axis of the aftmost of the propulsion units. The marine vessel (10) comprises four quadrants (I, II, III, IV) defined by the longitudinal centre line (L) and the transversal line (T) wherein a first (I) and a second (II) quadrant are located on the same side of said longitudinal centre line (L). When a combined sway and yaw motion is desired, the thrust of one propulsion unit is directed towards the second (I) quadrant, and the thrust of the other propulsion units is directed towards the first (II) quadrant.

In a marine propulsion system, a controller determines a point of action of a resultant force of first propulsion devices at a stern of a hull during a parallel motion based on a target direction and a required propulsion force, controls the first propulsion devices to apply the resultant force in the target direction to the point of action, and controls a second propulsion device in front of the stern to apply a propulsion force to cancel undesired components of the resultant propulsion force. The controller moves the point of action backward as the required propulsion force increases during the parallel motion, and increases the propulsion force of one first propulsion device in a forward direction when the point of action reaches a rear limit position and the propulsion force of another first propulsion device in a backward direction reaches an upper limit propulsion force.

In a marine propulsion system, a controller determines a point of action of a resultant force of first propulsion devices at a stern of a hull during a parallel motion based on a target direction and a required propulsion force, controls the first propulsion devices to apply the resultant force in the target direction to the point of action, and controls a second propulsion device in front of the stern to apply a propulsion force to cancel undesired components of the resultant propulsion force. The controller moves the point of action backward as the required propulsion force increases during the parallel motion, and increases the propulsion force of one first propulsion device in a forward direction when the point of action reaches a rear limit position and the propulsion force of another first propulsion device in a backward direction reaches an upper limit propulsion force.