Hydrofoil Boat With Counter-Rotating Propellers for Lower Drag

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Solution Overview

Problem

Existing hydrofoil boats require high propulsion power due to drag and mechanical components, leading to increased noise and environmental impact.

Innovation Solution

A hydrofoil boat design featuring a first and second hydrofoil attached to the hull via separate fastening arrangements, with a motor pod and counter-rotating propellers mounted on a turnable strut, eliminating mechanical power transmission and reducing drag through torque cancellation and streamlined design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single propeller with mechanical power transmission is used, then the propulsion system is simpler, but the drag increases and the strut must be thicker to handle gyroscopic effects

Engineering Contradiction:

Improvepropulsion system complexityVSAvoiddrag

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The single propeller is segmented into two counter-rotating propellers. This segmentation allows the gyroscopic effects to cancel each other out, enabling the use of a thinner, more streamlined strut that reduces drag while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The propellers are designed to rotate in opposite directions (counter-rotation), creating asymmetric rotational motion that cancels out gyroscopic effects. This asymmetric design allows for a more streamlined strut configuration that reduces drag.

Inventive Principle:

Principle #4Asymmetry

2Strength

If the strut is made thicker to reduce deflections from gyroscopic effects, then the strut strength increases, but the boat drag increases

Engineering Contradiction:

Improvestrut strengthVSAvoidboat drag

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The second propeller acts as a counterweight to the first propeller's gyroscopic effects by rotating in the opposite direction. This counter-rotation cancels out the gyroscopic moments, allowing the strut to be thinner and more streamlined, thereby reducing drag while maintaining sufficient strength.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

3Power

If internal combustion engines are used for propulsion, then the power capacity is sufficient, but the noise and environmental impact increase

Engineering Contradiction:

Improvepropulsion power capacityVSAvoidnoise and environmental impact

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The internal combustion engine is replaced with an electric motor system. This substitution eliminates the noise and environmental pollution associated with combustion engines while providing sufficient propulsion power for the hydrofoil boat.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If a single large propeller is used, then the mechanical power transmission is simpler, but the torque distribution is less efficient

Engineering Contradiction:

Improvepower transmission complexityVSAvoidtotal torque and available power

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The single large propeller is divided into two smaller counter-rotating propellers. This segmentation distributes the torque load across two propellers, increasing the total torque output and available power while the direct-drive electric motors keep the power transmission system relatively simple.

Inventive Principle:

Principle #1Segmentation

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

The design achieves reduced propulsion power requirements, decreased drag, and lower noise levels by utilizing counter-rotating propellers and a streamlined strut, allowing for a smaller motor pod and efficient steering.

Implementation Method 1

By the counter-rotating propellers, torques around a roll axis of the boat, caused by the propellers, may cancel each other

Methodology Applied

Scientific EffectTorque cancellation: Angular Momentum Conservation

Implementation Method 2

By means of hydrofoils, a boat can assume a hydrofoil mode of progress. At the hydrofoil mode, the hull is lifted out of the water

Methodology Applied

Scientific EffectHydrofoil lift: Aerofoil

Implementation Method 3

the strut and the motor pod are turnable in relation to the hull for steering the boat

Methodology Applied

Scientific EffectVector force redirection: Force

Data Source

PatentUS12434789B2Hydrofoil boat

Publication Date: 2025.10.07 CANDELA TECH AB

AI summary

The invention involves a boat comprising —a hull (2), —a first hydrofoil (301) fastened to the hull (2) by means of a first fastening arrangement (302), and —a second hydrofoil (601) fastened to the hull (2) by means of a second fastening arrangement (503) which is separate from the first fastening arrangement (302), —wherein the second fastening arrangement comprises a strut (503) arranged to extend at least partly downwards from the hull (2), the second hydrofoil being fixed to the strut, —wherein that the boat comprises a motor pod (502) fixed to the strut (503), —wherein the strut and the motor pod are turnable in relation to the hull for steering the boat, —wherein the motor pod comprises a casing, a power supply assembly housed in the casing, and two propellers arranged to be driven by the power supply assembly, —wherein the propellers (5011, 5012) are counter-rotating.