Pivoting Hydrofoil Angle Control for Watercraft Stability
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Solution Overview
Problem
Existing hydrofoil boat designs face challenges in efficiently controlling the angle of attack, particularly in rough waters and varying wind conditions, with incidence-controlled systems being less efficient and vulnerable to drag and ventilation, while surface-piercing designs struggle with maintaining optimal foil position and stability.
Innovation Solution
The hydrofoil is pivotally connected to the hull with a pivot axis near the lift and drag vectors, utilizing a trailing wand sensor and a flexible system with a spring and dampener to maintain low pitching moments and adjust ride height, allowing the hydrofoil to pitch up or down with minimal force and maintain equilibrium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the hydrofoil pierces the surface at an angle close to 90 degrees, then drag and spray are reduced and the foil is less susceptible to ventilation, but the mechanism to control the angle of attack becomes more complex
Solution Approach 1:
The hydrofoil system uses self-regulating mechanisms where the foil's own motion and hydrodynamic forces control its angle of attack. The pivot connection allows the foil to automatically adjust its pitch based on ride height changes, eliminating the need for complex active control systems while maintaining optimal piercing angle for reduced drag and spray.
Solution Approach 2:
The control system transitions from static fixed-angle foils to dynamically adjustable foils that can change their angle of attack in real-time. The pivot connection enables continuous adjustment of the foil's pitch angle as the boat moves through waves, allowing the system to adapt to changing conditions while maintaining the beneficial 90-degree piercing angle.
2Measurement precision
If incidence controlled hydrofoils use a forward facing sensor, then the sensor can effectively sense the ride of the boat, but the sensor is vulnerable and adds considerable length to the boat
Solution Approach 1:
Instead of placing the sensor at the front of the boat facing forward, the system inverts the sensing approach by using a trailing sensor that faces backward. This reversal protects the sensor from forward impacts and reduces the boat's overall length while maintaining effective ride height sensing through the trailing wand mechanism.
Solution Approach 2:
The patent introduces a trailing wand as an intermediary element that extends the sensing capability backward from the hull. This mediator allows the sensor to be positioned away from the vulnerable front area while still accurately measuring ride height changes through the trailing wand's motion, effectively decoupling sensor placement from sensing accuracy.
3Productivity
If the whole hydrofoil pitches to change angle of incidence, then lift control is more efficient, but the lift vector moves fore and aft creating dramatic pitching moments on the hydrofoil
Solution Approach 1:
The patent separates the pitch control function from the lift generation function. Instead of pitching the entire hydrofoil, only the control surface (flap or spoiler) is extracted and made independently pitchable. This allows lift control through localized angle of attack changes on the control surface while the main hydrofoil remains stable, preventing dramatic pitching moments.
Solution Approach 2:
The hydrofoil system is segmented into distinct functional parts: the main hydrofoil body for lift generation and a separate control surface for angle of attack adjustment. This segmentation allows independent control of each function, enabling efficient lift modulation through control surface pitching while maintaining overall hydrofoil stability and minimizing unwanted pitching moments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces drag, enhances stability, and allows for easy adjustment of ride height and frequency response, while ensuring the hydrofoil remains efficient and less vulnerable to wave disturbances, enabling effective control of the angle of incidence and lift generation.
Implementation Method 1
hydrofoils can reduce the drag of a hull going through the water and they can provide a smoother ride
Implementation Method 2
flexible system with a spring and dampener
Implementation Method 3
flexible system with a spring and dampener
Implementation Method 4
when hydrofoil pitches the moments on the hydrofoil are small
Data Source
AI summary
A watercraft having a hull, a mast with sail, an aft rudder and a hydrofoil projecting below the bottom of the hull. The hydrofoil is pivotly connected to the hull enabling the hydrofoil to pitch on a pivot axis which is essentially perpendicular to the longitudinal axis of the hull. The hydrofoils have a vertical part which produces lateral forces to accelerate the boat in turns and resist lateral forces from the sail, and a vertical portion which curves into the horizontal portion which produces vertical lift. The angle of incidence of the hydrofoil is controlled by a sensor arm carrying a trailing sensor.