Collision-avoidance maneuvering method in congested water and collision-avoidance maneuvering system for single-propeller twin-rudder ship

1. A collision-avoidance maneuvering method in congested water, in which when two ships crossing each other on a course in congested water are likely to collide with each other, an own ship is maneuvered with collision avoidance while viewing another ship on a starboard side,

the method comprising the steps of:

maneuvering the own ship decelerated so as to avoid collision with the other ship, the own ship being decelerated by astern power against an inertial force applied in a forward direction of the own ship, the own ship being continuously navigated on a current target course with a propulsion propeller always rotated forward at a stern of the own ship, the astern power being generated as propulsion of a propeller slipstream with rudder angles formed at a pair of right and left high-lift rudders disposed behind the propulsion propeller;

controlling, in the decelerating maneuvering, the rudder angles formed at the high-lift rudders within a range from a rudder angle for applying a maximum propeller slipstream as the astern power to a rudder angle for eliminating ahead power of the propeller slipstream, and controlling the deceleration of the own ship by changing the astern power according to the rudder angles; and

controlling the rudder angles of the high-lift rudders so as to continuously navigate the own ship on the target course by using the propulsion of the propeller slipstream as the ahead power after the other ship crosses the course of the own ship.

2. A collision-avoidance maneuvering method in congested water, in which when two ships crossing each other on a course in congested water are likely to collide with each other, an own ship is maneuvered with collision avoidance while viewing another ship on a starboard side,

the method comprising the steps of:

maneuvering the own ship decelerated so as to avoid collision with the other ship, the own ship being decelerated by astern power against an inertial force applied in a forward direction of the own ship, the own ship being continuously navigated on a current target course with a propulsion propeller always rotated forward at a stern of the own ship, the astern power being generated as propulsion of a propeller slipstream with rudder angles formed at a pair of right and left high-lift rudders disposed behind the propulsion propeller;

setting, in the decelerating maneuvering, the rudder angles formed at the high-lift rudders at a rudder angle for applying a maximum propeller slipstream as the astern power, and changing a number of revolutions of the propulsion propeller with a constant forward rotation, and controlling the deceleration of the own ship by changing the astern power according to the number of revolutions of the propeller; and

controlling the rudder angles of the high-lift rudders so as to continuously navigate the own ship on the target course by using the propulsion of the propeller slipstream as the ahead power after the other ship crosses the course of the own ship.

3. The collision-avoidance maneuvering method in congested water according to claim 1 , wherein in the decelerating maneuvering, the astern power is controlled according to a distance from the other ship and a speed of the own ship is reduced so as to obtain a time required for the other ship to cross the course of the own ship.

4. The collision-avoidance maneuvering method in congested water according to claim 1 , wherein if difficulty arises in reducing a speed of the own ship so as to obtain a time required for the other ship to cross the course of the own ship, the rudder angles formed at the high-lift rudders are controlled within a range of a rudder angle for applying a propeller slipstream as astern power, and a collision is avoided by turning a stern so as to change a moving direction of the own ship while the astern power is applied to reduce the speed of the own ship.

5. A collision-avoidance maneuvering system for a single-propeller twin-rudder ship, the single-propeller twin-rudder ship comprising a propulsion propeller disposed at a stern of the ship, a pair of right and left high-lift rudders disposed behind the propulsion propeller, a pair of rotary-vane steering engines for driving the respective high-lift rudders, a steering controller for controlling a direction of a ship motion by combining rudder angles of the two high-lift rudders, and a ship radar,

wherein in a collision-avoidance maneuvering mode for navigation in congested water, the steering controller performs collision-avoidance maneuvering in response to a collision alarm signal transmitted from the ship radar when another ship crossing a course of an own ship is likely to collide with the own ship, the own ship being decelerated so as to avoid collision with the other ship by astern power against an inertial force applied in a forward direction of the own ship, the own ship being continuously navigated on a current target course while viewing the other ship on a starboard side with the propulsion propeller always rotated forward, the astern power being generated as propulsion of a propeller slipstream with rudder angles formed at the high-lift rudders,

in the decelerating maneuvering, the rudder angles formed at the high-lift rudders are controlled within a range from a rudder angle for applying a maximum propeller slipstream as the astern power to a rudder angle for eliminating the ahead power of the propeller slipstream, the astern power that changes with the rudder angle is controlled according to a distance from the other ship, and the speed of the own ship is reduced so as to obtain a time required for the other ship to cross the course of the own ship, and

the rudder angles of the high-lift rudders are controlled so as to continuously navigate the own ship on the target course by using the propulsion of the propeller slipstream as the ahead power after the other ship crosses the course of the own ship.

6. A collision-avoidance maneuvering system for a single-propeller twin-rudder ship, the single-propeller twin-rudder ship comprising a propulsion propeller disposed at a stern of an own ship, a pair of right and left high-lift rudders disposed behind the propulsion propeller, a pair of rotary-vane steering engines for driving the respective high-lift rudders, a steering controller for controlling a direction of a ship motion by combining rudder angles of the two high-lift rudders, and a ship radar,

wherein in a collision-avoidance maneuvering mode for navigation in congested water, the steering controller performs collision-avoidance maneuvering in response to a collision alarm signal transmitted from the ship radar when another ship crossing a course of the own ship is likely to collide with the own ship, the own ship being decelerated so as to avoid collision with the other ship by astern power against an inertial force applied in a forward direction of the own ship, the own ship being continuously navigated on a current target course while viewing the other ship on a starboard side with the propulsion propeller always rotated forward, the astern power being generated as propulsion of a propeller slipstream with rudder angles formed at the high-lift rudders,

in the decelerating maneuvering, the rudder angles formed at the high-lift rudders are set at a rudder angle for applying a maximum propeller slipstream as the astern power, a number of revolutions of the propulsion propeller is changed with a constant forward rotation, the astern power that changes with the number of revolutions of the propeller is controlled according to a distance from the other ship, and a speed of the own ship is reduced so as to obtain a time required for the other ship to cross the course of the own ship, and

the rudder angles of the high-lift rudders are controlled so as to continuously navigate the own ship on the target course by using the propulsion of the propeller slipstream as the ahead power after the other ship crosses the course of the own ship.

7. The collision-avoidance maneuvering system for a single-propeller twin-rudder ship according to claim 5 , wherein if the speed of the own ship is unable to decrease so as to obtain a time required for the other ship to cross the course of the own ship, the rudder angles formed at the high-lift rudders are controlled by the steering controller within a range of a rudder angle for applying a propeller slipstream as astern power, and a stern is turned so as to change a moving direction of the own ship while the astern power is applied to reduce the speed of the own ship.

8. The collision-avoidance maneuvering system for a single-propeller twin-rudder ship according to claim 5 , wherein the steering controller controls the rudder angles formed at the high-lift rudders according to a distance relationship with at least one other ship, a relationship between moving directions of the ships, and a relationship between relative speeds of the ships.

9. The collision-avoidance maneuvering method in congested water according to claim 2 , wherein in the decelerating maneuvering, the astern power is controlled according to a distance from the other ship and a speed of the own ship is reduced so as to obtain a time required for the other ship to cross the course of the own ship.