Auxiliary Propeller Position Control in Dual-Drive Watercraft

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Solution Overview

Problem

Existing watercraft propulsion systems with multiple propulsion devices face issues of useless driving when the auxiliary propulsion device's propeller is above water, preventing effective propulsive force application, leading to inefficiency and unnecessary energy consumption.

Innovation Solution

A watercraft propulsion system with a controller that restricts the combined use of main and auxiliary propulsion devices when the auxiliary device's propeller is above water, ensuring both devices are not driven in this state, and automatically lowers the propeller into the water when a combined use mode is commanded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the auxiliary propulsion device's propeller is kept above water to avoid sailing resistance, then the auxiliary device can be ready for quick deployment, but the combined use mode cannot be activated and both propulsion devices cannot work together

Engineering Contradiction:
Improveauxiliary propulsion readinessVSAvoidcombined use capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary action by automatically lowering the auxiliary propulsion device's propeller into the water when combined use mode is selected, before the propulsion can actually occur. This preliminary positioning enables the propeller to be in the correct state for effective operation, resolving the contradiction between readiness and combined use capability.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If the operator manually lowers the propeller before combined use mode, then effective propulsion can be achieved, but the operation becomes more complex and time-consuming

Engineering Contradiction:
Improvepropulsion effectivenessVSAvoidoperation simplicity
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system implements self-service by automatically performing the propeller lowering action when combined use mode is selected. The control device monitors the mode selection and autonomously adjusts the propeller position, eliminating the need for manual operator intervention and reducing operational complexity while ensuring propulsion effectiveness.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If the auxiliary propulsion device is driven with propeller above water, then the device can be operated, but useless driving occurs and energy is wasted without effective propulsive force application

Engineering Contradiction:
Improvedevice operabilityVSAvoidenergy waste from useless driving
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The system employs feedback by monitoring the propeller position and the selected control mode to determine whether to permit operation. When combined use mode is selected and the propeller is above water, the control device detects this state and prevents operation, thereby avoiding useless driving and energy waste while maintaining ease of operation through automated control.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4365075B1Watercraft propulsion system, watercraft and watercraft propulsion control method
Publication Date: 2026.04.08 YAMAHA MOTOR CO LTD
  • EP4365075B1 patent drawingFigure 1
  • EP4365075B1 patent drawingFigure 2
  • EP4365075B1 patent drawingFigure 3

AI summary

A watercraft propulsion system (100) includes a main propulsion device (OM) attachable to a hull (2), an auxiliary propulsion device (EM) attachable to the hull (2) and having a lower rated output than the main propulsion device (OM), a lift (69) to move up and down a propeller (60) of the auxiliary propulsion device (EM) between an underwater position and an above-water position, and a controller (101). The controller (101) is configured or programmed to restrict the auxiliary propulsion device (EM) from being driven when the propeller (60) of the auxiliary propulsion device (EM) is in the above-water position.