Purse Seine Net Assembly Material Differentiation
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Solution Overview
Problem
Conventional purse seine fishery nets made of nylon are prone to degradation from ultraviolet rays, require significant weight to sink quickly, and experience increased weight and towing force when wet, leading to reduced strength and frequent replacement needs.
Innovation Solution
A net assembly using a combination of nylon for the fish capture and longitudinal end parts and polyester or high-density polyethylene for the body, upper, and lower end parts, optimizing material properties for quick sinking, high tensile strength, and resistance to ultraviolet exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If nylon material is used for the net, then the net has elasticity and tensile strength required for fishing operations, but the net degrades when exposed to ultraviolet rays and requires frequent replacement
Solution Approach 1:
The patent applies different materials to different parts of the net based on their specific functional requirements. The body net uses polyester for UV resistance, while the end nets use nylon for elasticity and impact absorption. This local differentiation resolves the contradiction by allowing each section to optimize for its primary function without compromising overall net performance.
Solution Approach 2:
The patent creates a composite net structure combining polyester and nylon materials in specific configurations. The polyester body net provides UV resistance and sinking properties, while nylon end nets provide elasticity. This composite approach resolves the contradiction by integrating the strengths of both materials in a unified net system.
2Strength
If nylon material is used for the net, then the net has the required elasticity for fishing operations, but the net absorbs significant moisture when wetted, increasing weight and requiring greater towing force
Solution Approach 1:
The patent limits nylon usage to only the end nets where elasticity is most critical for capturing fish, while the body net uses polyester which has lower moisture absorption. This local application resolves the contradiction by minimizing the total nylon content and thus reducing overall moisture absorption and weight increase when wet.
3Strength
If nylon material is used for the net, then the net has the required tensile strength, but the specific gravity is close to seawater requiring considerable weight to be attached to sink quickly
Solution Approach 1:
The patent uses polyester for the body net which has higher specific gravity than nylon, enabling faster sinking without additional weights. Nylon is reserved for end nets where tensile strength and elasticity are prioritized over sinking speed. This material differentiation resolves the contradiction by optimizing each section for its primary function.
Solution Approach 2:
The composite net structure combines polyester body nets with higher specific gravity for rapid sinking and nylon end nets for strength. This material composition resolves the contradiction by allowing the net to sink quickly through the polyester sections while maintaining overall structural integrity through the nylon components.
4Productivity
If the net is made to have predetermined length and width by coupling multiple nets, then the net can prevent fish from escaping, but the overall strength and abrasion resistance are reduced
Solution Approach 1:
The patent uses stronger polyester material for the body net sections that require high abrasion resistance and tensile strength, while using nylon only for the end nets where flexibility and impact absorption are more important. This local material differentiation resolves the contradiction by ensuring high-strength sections are positioned where they are most needed.
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 net assembly is designed to minimize weight, enhance tensile strength, and improve abrasion resistance, allowing for efficient and quick fish capture while reducing damage to fish and the need for frequent replacements.
Implementation Method 1
corks or floats providing buoyancy to allow the upper end of the net to be placed on the surface of seawater
Implementation Method 2
a weight body is coupled to the lower end of the net to allow the lower end of the net to sink below the surface of seawater
Data Source
AI summary
A net assembly used for purse seine fishery, which is mounted on a first vessel, dropped into seawater from the first vessel, and towed by a second vessel to surround and pull fish to capture fish. The net assembly includes a plurality of floats floating on a surface of seawater to provide buoyancy to the net assembly, and coupled to one another in a spaced manner in a lengthwise direction of the net assembly; a net combination of a plurality of nets disposed under the floats in an inter-coupled state, and sunken and deployed from the surface of seawater to surround and capture fish; a weight body extending along a lower end of the net combination to provide a sinking force by means of gravity to sink the net combination; and a purse wire extending along the net combination while being spaced apart from the weight body in a downward direction, and tightened by the first vessel to allow the net assembly to form a closed space below the surface of seawater.