Helix Rope Drag Reduction via Braided Sheath Design
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Solution Overview
Problem
Helix ropes used in pelagic trawls exhibit excessive drag, leading to increased fuel consumption and reduced catch per unit effort, which has resulted in them falling out of favor despite their environmental benefits and self-spreading properties.
Innovation Solution
A helix rope construction with a braided sheath formed by more than sixteen strands, including a larger and more elastic helixing strand, which reduces drag and enhances strength, achieved by using a braiding machine with greater than sixteen carriers and optimizing strand configuration for minimal void space and maximal abrasion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If coverbraided ropes (including helix ropes) are used in pelagic trawls, then strength and durability are improved, but drag increases and cost increases
Solution Approach 1:
The patent changes the structural parameters of the rope by transitioning from traditional braided constructions to a helical configuration with specifically controlled pitch and diameter ratios. This parameter optimization reduces the rope's cross-sectional area and streamlines its shape, thereby reducing drag while preserving strength characteristics.
Solution Approach 2:
The invention employs composite construction by combining multiple strands with different properties (helix strand, filler strands, sheath materials) to create a rope that simultaneously achieves reduced drag and maintained strength. The composite structure allows each component to contribute specific functional properties.
2Adaptability or versatility
If helix ropes with traditional strand configuration are used, then self-spreading properties are achieved, but drag remains excessive
Solution Approach 1:
The patent optimizes geometric parameters including helix pitch, strand diameter ratios, and braid angle to achieve the optimal balance between self-spreading capability and drag reduction. The specific parameter ranges disclosed minimize void space while maintaining the rope's ability to spread in water.
Solution Approach 2:
The invention applies different local qualities to different parts of the rope structure - the helix strand provides self-spreading and drag reduction, while filler strands and sheath provide strength and protection. This localized functional differentiation resolves the contradiction between self-spreading and drag.
3Ease of manufacture
If traditional braided rope constructions are used, then ease of splicing is achieved, but strength and drag performance are insufficient
Solution Approach 1:
The patent modifies the structural parameters to include standardized eye formation capabilities and splicing interfaces, making the helical construction compatible with traditional splicing methods while maintaining the drag-reduced helical geometry in the main rope body.
Data Source
AI summary
Methods are provided for forming a spliced eye (220) of a sling (222) made from a rope that includes a core rope (37) and includes a braided sheath (398).