Small boat

Abstract

A small boat includes engines mounted on a hull, a plurality of water jet propulsion units disposed on both sides of a longitudinal axis of the hull and driven by the engines, and a steering wheel arranged to change jet directions of the water jet propulsion units. The small boat further includes a steering angle sensor arranged to detect a rotational angle of the steering wheel, front and rear gravity sensors arranged to detect a turning state of the hull, and a control device to which the rotational angle and the turning state of the hull are inputted in order to control thrusts of the water jet propulsion units such that the turning state coincides with any one of a group of target steady turning radii corresponding to the rotational angle of the steering wheel. The small boat turns along the steady radius regardless of any water conditions.

1 . A boat comprising:
 at least one engine mounted on a hull;   a plurality of water jet propulsion units disposed on both sides of a longitudinal axis of the hull and driven by the at least one engine;   a steering wheel arranged to change jet directions of the water jet propulsion units;   a steering angle sensor arranged to detect a rotational angle of the steering wheel;   a running state detection device arranged to detect a running state of the hull; and   a control device arranged to receive the rotational angle of the steering wheel detected by the steering angle sensor and the running state of the hull detected by the running state detection device, and control thrusts of the water jet propulsion units such that the running state coincides with a target running track corresponding to the rotational angle of the steering wheel.   
   
   
       2 . The boat according to  claim 1 , wherein the control device is arranged to determine, based on the rotational angle of the steering wheel, that the hull is in a turning state, and control the thrusts of the water jet propulsion units such that the turning state coincides with a target steady turning radius corresponding to the rotational angle of the steering wheel as detected by the steering angle sensor. 
   
   
       3 . The boat according to  claim 2 , further comprising:
 a throttle device operable by an operator in order to adjust an output of the engine; and   a throttle position sensor arranged to detect a displacement of the throttle device; wherein   the control device establishes the target steady turning radius based on the rotational angle of the steering wheel and the displacement detected by the throttle position sensor.   
   
   
       4 . The boat according to  claim 2 , further comprising a speed sensor arranged to detect a running speed of the boat, wherein the control device establishes the target steady turning radius based on the rotational angle of the steering wheel and the running speed detected by the speed sensor. 
   
   
       5 . The boat according to  claim 1 , wherein the running state detection device includes a plurality of gravity sensors arranged to detect acceleration due to centrifugal force, the plurality of gravity sensors being provided along the longitudinal axis of the hull. 
   
   
       6 . The boat according to  claim 1 , wherein one of the at least one engine is provided per each water jet propulsion unit. 
   
   
       7 . The boat according to  claim 1 , further comprising a thruster provided on the hull and arranged to generate a lateral thrust that crosses the longitudinal axis of the hull at substantially a right angle, wherein the control device controls the thrust of the thruster such that the running state coincides with the target steady turning radius. 
   
   
       8 . The boat according to  claim 7 , wherein a plurality of the thrusters are provided along the longitudinal axis of the hull. 
   
   
       9 . A boat comprising:
 at least one engine mounted on a hull;   a plurality of water jet propulsion units disposed on both sides of a longitudinal axis of the hull and driven by the engine;   a steering wheel provided on the hull;   a steering angle sensor arranged to detect a rotational angle of the steering wheel;   a running state detection device arranged to detect a running state of the hull; and   a control device arranged to receive the rotational angle of the steering wheel detected by the steering angle sensor and the running state of the hull detected by the running state detection device, and to control a water jet direction of each of the water jet propulsion units such that the running state coincides with a target running track corresponding to the rotational angle of the steering wheel.   
   
   
       10 . The boat according to  claim 9 , wherein the control device is arranged to determine, based on the rotational angle of the steering wheel, that the hull is in a turning state, and control the water jet directions of the water jet propulsion units such that the turning state coincides with a target steady turning radius corresponding to the rotational angle of the steering wheel. 
   
   
       11 . The boat according to  claim 10 , further comprising:
 a throttle device operable by an operator in order to adjust an output of the at least one engine; and   a throttle position sensor arranged to detect a displacement of the throttle device; wherein   the control device establishes the target steady turning radius based on the rotational angle of the steering wheel and the throttle displacement detected by the throttle position sensor.   
   
   
       12 . The boat according to  claim 10 , further comprising a speed sensor arranged to detect a running speed of the boat, wherein the control device establishes the target steady turning radius based on the rotational angle of the steering wheel and the running speed detected by the speed sensor. 
   
   
       13 . The boat according to  claim 9 , wherein the running state detection device includes a plurality of gravity sensors arranged to detect acceleration due to centrifugal force, and a plurality of the gravity sensors are provided along the longitudinal axis of the hull. 
   
   
       14 . The boat according to  claim 9 , wherein one of the at least one engine is provided per each water jet propulsion unit. 
   
   
       15 . The boat according to  claim 9 , further comprising a thruster provided on the hull and arranged to generate a lateral thrust that crosses the longitudinal axis of the hull at substantially a right angle, wherein the control device controls the thrust of the thruster such that the turning state coincides with the target steady turning radius. 
   
   
       16 . The boat according to  claim 15 , wherein a plurality of the thrusters are provided along the longitudinal axis of the hull.