Flexible Fin Propulsion with Adjustable Tensioning
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Solution Overview
Problem
Existing oscillating fin propulsion systems for watercraft lack efficiency due to suboptimal fin design and material distribution, leading to reduced thrust and maneuverability.
Innovation Solution
The use of flexible fins with square top ends and a sawtooth configuration, combined with adjustable tensioning at the trailing edge, enhances fin twist and cord-wise stiffness, mimicking sailboat sail dynamics for improved propulsion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional fin designs are used, then the propulsion system is simple, but thrust efficiency is reduced
Solution Approach 1:
The fin employs different material properties in different regions: the leading edge uses softer rubber for flexibility and twist, while the trailing edge uses harder rubber for stiffness and structural support. This local differentiation optimizes thrust efficiency without requiring complex mechanical structures.
Solution Approach 2:
The fin is constructed from composite rubber materials with varying hardness and flexibility characteristics. The combination of soft and hard rubber regions creates a naturally optimized structure that enhances propulsion efficiency while maintaining simplicity.
2Shape
If flexible fins are used, then fin twist and angle of attack are improved, but cordwise stiffness is reduced
Solution Approach 1:
The fin design implements local quality differentiation where the leading edge region is softer to enable twist and angle of attack adjustment, while the trailing edge region is harder to maintain cordwise stiffness. This spatial variation in material properties resolves the contradiction between flexibility and strength.
3Productivity
If uniform material distribution is used, then manufacturing is simple, but hydrodynamic performance is reduced
Solution Approach 1:
The fin employs local quality differentiation with softer rubber at the leading edge and harder rubber at the trailing edge. This material distribution optimizes hydrodynamic performance by enabling proper twist and stiffness characteristics, while the integration process remains manufacturable.
4Adaptability or versatility
If adjustable tensioning is added, then customization and control are improved, but device complexity increases
Solution Approach 1:
The fin incorporates adjustable tensioning mechanisms that allow dynamic modification of the fin's stiffness and twist characteristics. This enables adaptation to different operators and vessel lengths, providing customizable pedaling resistance while maintaining relatively simple mechanism design.
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 design increases thrust and efficiency by optimizing fin shape and stiffness, allowing for customizable pedaling resistance and improved hydrodynamic performance across various operators and vessel lengths.
Implementation Method 1
said flexible fins can twist to form an angle of attack for providing forward thrust with respect to the longitudinal dimension of the watercraft while moving in both directions along said arcuate path
Data Source
AI summary
A watercraft having propulsion means extending below the water line comprising a pair of flexible fins each adapted to oscillate through an arcurate path in a generally transverse direction across the central longitudinal dimension of the watercraft. As input force is applied, the fins twist to form an angle of attack for providing forward thrust while moving in both directions along the arcurate path. Each of the fins have a generally squared off top and preferably an outer area of harder rubber than the inner area. Each of the fins can be adjusted at the trailing edge to provide adjustable tensioning of the trailing edge.