Bow Thruster and Stern Steering for Fixed-Point Hull Holding

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Solution Overview

Problem

Existing ship position control systems, such as U.S. Pat. No. 6,032,087, fail to effectively eliminate both anteroposterior and lateral positional offsets of a hull, with a focus primarily on azimuthal offset correction.

Innovation Solution

A watercraft propulsion system incorporating a bow thruster for lateral force and a propulsion device on the stern with variable steering, controlled by a controller to switch between translation and bow turning modes for precise position and azimuth maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the bow thruster alone is used to eliminate azimuthal offset, then the system is simple, but the elimination precision is insufficient

Engineering Contradiction:

Improvesystem simplicityVSAvoidazimuth offset elimination precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines the bow thruster and stern propulsion device into a coordinated control system. The controller simultaneously manages both devices to eliminate azimuthal offset, merging their functions to achieve higher precision than either device could accomplish alone.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The stern propulsion device is designed with variable steering angle capability, allowing it to perform multiple functions: generating anteroposterior propulsive force for position maintenance and generating lateral propulsive force for azimuth correction. This multi-functionality eliminates the need for dedicated azimuth correction equipment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If the propulsive force of additional propulsion devices is used to eliminate azimuthal offset, then the elimination precision improves, but the device complexity increases

Engineering Contradiction:

Improveazimuth offset elimination precisionVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The stern propulsion device serves dual purposes: maintaining position through anteroposterior propulsive force and eliminating azimuthal offset through lateral propulsive force generated by variable steering angle. This eliminates the need for additional dedicated azimuth correction equipment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The steering angle of the stern propulsion device is dynamically adjusted based on control requirements. The variable steering angle allows the system to adapt to different operational modes (translation mode and bow turning mode), providing flexibility without adding fixed structural complexity.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If the hull position is maintained by controlling only the propulsive force of the propulsion device with fixed steering angle, then the control is simple, but the position and azimuth maintenance precision is insufficient

Engineering Contradiction:

Improvecontrol simplicityVSAvoidposition and azimuth maintenance precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The stern propulsion device features variable steering angle capability, allowing dynamic adjustment between translation mode steering angle and bow turning mode steering angle. This enables precise control of both position and azimuth by adapting the steering angle to the specific control requirement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control system is segmented into two distinct modes: translation mode for position maintenance and bow turning mode for azimuth adjustment. This segmentation allows each mode to be optimized independently while maintaining overall system simplicity through clear operational boundaries.

Inventive Principle:

Principle #1Segmentation

4Device complexity

If the system operates in a single control mode, then the control logic is simple, but the adaptability to different operational requirements is limited

Engineering Contradiction:

Improvecontrol logic simplicityVSAvoidadaptability to operational requirements

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The control system dynamically switches between translation mode and bow turning mode based on operational requirements. The steering angle and propulsive force are dynamically adjusted according to the current mode, enabling the system to adapt to different scenarios while maintaining clear, manageable control logic for each mode.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12466530B2Watercraft propulsion system, and watercraft including the watercraft propulsion system

Publication Date: 2025.11.11 YAMAHA MOTOR CO LTD

AI summary

A watercraft propulsion system includes a bow thruster to generate a lateral propulsive force, a propulsion device on a stern of a hull and having a variable steering angle, and a controller configured or programmed to control the bow thruster and the propulsion device to perform a fixed point holding control to maintain a position and an azimuth of the hull. The fixed point holding control includes a translation mode in which the hull position is maintained by controlling the propulsive force of the propulsion device with the steering angle set to a translation mode steering angle and the hull azimuth is adjusted by controlling the propulsive force of the bow thruster, and a bow turning mode in which the hull azimuth is adjusted by controlling the propulsive forces of the bow thruster and the propulsion device with the steering angle set to a bow turning mode steering angle.