Steerable Saildrive Control for Speed-Dependent Rudder Support

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Solution Overview

Problem

Conventional sailboat steering systems lack the ability to independently control the saildrive's steering angle and rudder angle at different boat speeds, limiting maneuverability and stability, especially during turns where hydrodynamic forces affect the hull.

Innovation Solution

A sailboat steering system with a steerable saildrive, a control lever for propeller speed, a rudder angle sensor, and an electronic control unit that adjusts the saildrive's steering angle based on the rudder angle and boat speed, allowing for independent setting of these angles to optimize turning performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the rudder angle and saildrive steering angle are fixed in a fixed ratio, then the system is simple to operate, but the maneuverability and stability performance cannot be optimized at different boat speeds

Engineering Contradiction:
Improvesteering control simplicityVSAvoidspeed-dependent steering optimization
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the relationship between rudder angle and saildrive steering angle based on boat speed. At different speeds, the electronic control unit calculates optimal angle combinations independently, allowing the steering characteristics to adapt to hydrodynamic conditions rather than maintaining a fixed mechanical linkage ratio.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters (rudder angle and steering angle) based on boat speed. The electronic control unit receives speed information and adjusts the angle parameters to optimize maneuverability at low speeds and stability at high speeds, moving away from a fixed parameter relationship.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the steerable saildrive is used to reduce turning radius, then the maneuverability is improved, but the system complexity increases due to additional control mechanisms

Engineering Contradiction:
Improveturning performanceVSAvoidsteering system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The system merges the steering functions of the rudder and the steerable saildrive into a coordinated control system. Both steering components work together under unified electronic control, combining their effects to achieve reduced turning radius while managing system complexity through integrated control logic.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electronic control unit implements feedback control by continuously monitoring the relationship between rudder angle, steering angle, and boat speed. This feedback mechanism allows the system to automatically adjust the saildrive steering angle to optimize turning performance without requiring complex manual coordination.

Inventive Principle:
Principle #23Feedback

3Device complexity

If the steering angle follows the rudder angle in a fixed ratio, then the control system is simple, but the stability and maneuverability cannot be optimized at different speeds

Engineering Contradiction:
Improvecontrol system complexityVSAvoidsteering performance reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control system transitions from a static fixed-ratio relationship to a dynamic speed-dependent relationship. The electronic control unit continuously adjusts the steering angle based on actual boat speed, ensuring reliable steering performance across different operating conditions rather than relying on a predetermined fixed ratio.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3494039B1Sailboat steering system and method for steering a sailboat
Publication Date: 2021.04.14 ZF FRIEDRICHSHAFEN AG
  • EP3494039B1 patent drawingFigure 1
  • EP3494039B1 patent drawingFigure 2

AI summary

The invention relates to a sailboat steering system (1) comprising a steerable saildrive (2), a control lever (3) for controlling a propeller speed of the steerable saildrive (2), a rudder angle sensor (4) to measure the ruder angle a of a rudder (5), and an electronic control unit (10), wherein the electronic control unit (10) is enabled to control a steering angle β of the steerable saildrive (2) depending on the position of the control lever (3) and depending on a rudder angle a of the rudder (5). The invention further comprises a method for steering a sailboat.