Anti-twist Frame for Hoisting Cable Twist Prevention
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Solution Overview
Problem
Existing methods for underwater installation of structures face challenges with hoisting cable twist, particularly in deep water, leading to cable damage and entanglement, and are limited to single vessel headings, making them ineffective in varying wind, wave, and swell directions.
Innovation Solution
A method involving a vessel with first and second hoisting means and an anti-twist frame (ATF) connected to the hoisting cables, where the vessel's heading is aligned with wind/wave/swell directions, and an anti-twist wire is used to minimize cable twist by selecting optimal connection points on the ATF, allowing for omnidirectional operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hoisting methods are used in deep water, then the object can be lowered to the seabed, but the hoisting cable rotates and twists about the vertical axis causing cable damage
Solution Approach 1:
The patent introduces an anti-twist frame as an intermediary device between the hoisting cable and the object. This frame includes a central part attached to the cable and circumferential parts extending radially outward, which act as a mediator to prevent the cable from rotating about the vertical axis while still allowing the object to be lowered to the seabed.
Solution Approach 2:
The anti-twist frame is attached to the hoisting cable before the lowering operation begins. The frame's circumferential parts are positioned in advance to interact with the water current, creating resistance that prevents cable rotation before any twisting can occur during the deep water lowering operation.
2Adaptability or versatility
If anti-twist beams are arranged on each side of the crane block, then cable twist is prevented for a single vessel heading, but the system cannot be used for multiple wind/wave/swell directions
Solution Approach 1:
The anti-twist frame is designed with circumferential parts that extend radially outward in multiple directions from the central part. This universal configuration allows the frame to effectively resist cable rotation regardless of the vessel's heading or the direction of wind, waves, or swells, making it adaptable to all operational conditions without requiring reconfiguration.
Solution Approach 2:
The anti-twist frame is designed to dynamically interact with the water current based on the vessel's heading and environmental conditions. The circumferential parts are positioned to optimize their interaction with the current direction, allowing the same structure to effectively prevent cable twist in varying wind, wave, and swell directions without requiring multiple different configurations.
3Adaptability or versatility
If the anti-twist frame uses fixed connection points, then the structure is simple, but it cannot be adjusted to minimize cable twist in different operating conditions
Solution Approach 1:
The anti-twist frame is segmented into a central part and multiple circumferential parts arranged radially around it. Each circumferential part can be independently positioned or connected at different locations, allowing the structure to be segmented and reconfigured to optimize its anti-twist performance for different vessel headings and environmental conditions while maintaining a relatively simple overall structure.
Data Source
AI summary
The invention relates to a method for lowering an object in a water body from a vessel floating on the water body, the vessel comprising first hoisting means with second hoisting means arranged on or near the vessel, with at least a first anti-twist frame (ATF) being connected to a lower end of a first hoisting cable of the first hoisting means, the object being attached to the lower end of the first hoisting cable, below the ATF. The method allows for adjusting the vessel's heading prior to carrying out the method, allowing the vessel to remain substantially aligned with the wind/wave direction, and at the same time preventing the first hoisting cable from being subjected to excessive twist.