Elastomeric Chain Mooring Line for Snatch Load Protection
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Solution Overview
Problem
Conventional mooring systems, particularly catenary mooring lines, face challenges such as high material costs, large seabed footprints, fatigue, and potential failure due to large wave loads and snatch loads, especially in deep-sea environments where they require extensive chain lengths and result in high operational and maintenance costs.
Innovation Solution
Incorporating elastomeric elements into mooring lines that stretch to absorb tensile loads, reducing peak loads on metal chains and providing shock protection, while maintaining a continuous metal chain as a failsafe to prevent line failure, allowing for a shorter and lighter mooring system with reduced wear and tear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional catenary mooring lines use long metal chains to provide restoring force, then the mooring system can handle large wave loads, but the material cost and seabed footprint increase significantly
Solution Approach 1:
The patent changes the physical state and mechanical properties of the mooring line by incorporating elastomeric elements that can stretch and elongate. This transforms the mooring system from a rigid metal chain configuration to a flexible composite structure that uses elastic deformation to provide restoring force, thereby reducing the required chain length and material quantity while maintaining load handling capability
Solution Approach 2:
The patent creates a composite mooring line by combining metal chain segments with elastomeric elements. The metal chain provides strength and anchoring capability, while the elastomeric elements provide elasticity and shock absorption. This composite structure reduces the overall material quantity needed compared to a pure metal chain system while maintaining or improving load handling capability
2Reliability
If mooring lines are over-engineered to prevent failure, then reliability increases, but the system size and operational costs increase
Solution Approach 1:
The patent incorporates elastomeric elements that act as shock absorbers and energy dissipaters before loads can cause damage to the metal chain components. These elements cushion against snatch loads and dynamic forces, providing beforehand protection that prevents failure without requiring excessive over-engineering of the entire system, thereby maintaining reliability while reducing system size and cost
3Force
If metal chains are used to provide restoring force through weight, then the mooring system is simple in design, but the weight and ballast requirements increase the device size
Solution Approach 1:
The patent substitutes the gravitational force mechanism (weight of chain) with an elastic force mechanism (stretch of elastomeric elements). Instead of relying on the weight of long chain segments to provide restoring force, the system uses the elastic properties of elastomeric materials to generate restoring force through deformation, thereby reducing the weight and ballast requirements while maintaining effective restoring force
4Quantity of substance
If the scope of mooring line is reduced to lower cost, then material costs decrease, but the ability to handle large displacements is compromised
Solution Approach 1:
The patent changes the mechanical behavior of the mooring line by incorporating elastomeric elements that can undergo large elastic deformations. This allows the system to accommodate large displacements between the floating object and anchor point without requiring a proportionally long chain, thereby reducing the scope (length per unit depth) while maintaining adaptability to handle large wave-induced displacements
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 elastomeric elements significantly reduce peak loads and wear on metal chains, extend the lifetime of mooring lines, and lower operational costs by enabling a smaller, more efficient mooring system that can handle large wave motions and tidal changes with reduced risk of failure.
Implementation Method 1
an elastomeric element attached to a mooring line between two points on the chain so that a section of the chain between the two points is bypassed. The elastomeric element is capable of stretching to a length which is less than the length of the section of chain
Implementation Method 2
Incorporating elastomeric elements into mooring lines that stretch to absorb tensile loads, reducing peak loads on metal chains and providing shock protection
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A mooring line (10) comprising a metal chain (24) and an elastomeric element (28) which is attached between two points of attachment (30, 32) thereby defining a bypass section (34) of metal chain (24). The elastomeric element (28) is arranged such that when an initial tensile load is applied, the elastomeric element (28) stretches from an initial length to a longer length wherein the bypass section (34) is not taut and thus the initial tensile load is transmitted from and to further sections (24) of the metal chain through the elastomeric element (28). When a further tensile load is applied, the elastomeric element (28) stretches to a length wherein the bypass section (34) becomes taut, and thus the further tensile load is transmitted directly from and to the further sections (24) of the metal chain through the bypass section (34).