Crane Vessel Hoist Cable Guide Stability
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Solution Overview
Problem
Existing crane vessels face challenges in stabilizing the hoisting cable during deep-water operations due to sea-state induced vessel motions, leading to increased compensation requirements and potential entanglement of hoisting cables.
Innovation Solution
The introduction of a hoist cable guide that engages the suspension cable part close to the vessel's motion center and center of gravity, reducing the impact of sea-state induced motions and preventing cable entanglement by adjusting the angle between cable parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suspension cable part is suspended directly from the boom without guidance, then the cable has more freedom of movement, but the cable becomes more susceptible to sea-state induced vessel motions and entanglement
Solution Approach 1:
A hoist cable guide is introduced as an intermediary device between the boom and the suspension cable part. The guide engages the cable part at a point close to the vessel's motion center and center of gravity, mediating the connection and reducing the cable's exposure to sea-state induced motions while preventing entanglement through controlled guidance paths.
2Adaptability or versatility
If the point of engagement of the suspension cable part is far from the vessel's motion center, then the cable has greater operational range, but the cable experiences larger sea-state induced motions requiring more compensation
Solution Approach 1:
The position parameter of the cable engagement point is changed from a fixed position on the boom to a guided position near the vessel's motion center. This parameter change reduces the lever arm effect of sea-state motions while the guide mechanism maintains operational flexibility through controlled cable routing.
3Reliability
If a heave compensator system is provided to compensate for sea-state induced vessel motions, then the cable stability is improved, but the device complexity and compensation requirements increase
Solution Approach 1:
The hoist cable guide is positioned and configured in advance to engage the suspension cable part at an optimal location near the vessel's motion center. This preliminary positioning reduces the magnitude of sea-state induced motions before they propagate to the cable, thereby reducing the compensation requirements for any heave compensator system that may be present.
4Stability of the object's composition
If the point of engagement is lowered closer to the center of gravity, then the vessel stability is improved, but the cable may experience increased interference from vessel motions
Solution Approach 1:
The hoist cable guide acts as an intermediary that decouples the cable from direct exposure to vessel motions. By positioning the guide near the center of gravity for stability while maintaining controlled cable routing, the guide mediates between the vessel's motion characteristics and the cable's operational requirements, reducing both entanglement risk and motion-induced instability.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The present invention relates to a crane vessel (1) and a method of lowering an object from such a crane vessel into the sea. The crane comprises a stationary pedestal (5), a crane housing (6) that is adapted to slew relative to the pedestal about a vertical rotation axis and a boom (11), comprising an inner end which is connected pivotably about a horizontal pivot axis (R2) to the crane housing. A luffing device extends between the boom and the crane housing, adapted to position the boom and actuate the up-and-down movement of the boom. Furthermore an object suspension device (18) is provided to which an object (10) is connectable, and a hoist assembly which comprises a winch (16) and an associated hoisting cable (17), the hoisting cable extending from the winch, via a departing sheave on the boom, to the object suspension device, such that upon actuation of the winch the object suspension device can be raised and lowered, wherein the one or more portions of the hoist cable between the boom and the object suspension device form one or more suspension cable parts. According to an aspect of the invention, a hoist cable guide (65) is provided which, at an operational position thereof, is adapted to guide at least one of the suspension cable parts between the boom and the object suspension device. According to the invention, the hoisting cable is provided as a multiple fall cable and a hoist cable retention device (H) is provided on the boom. The hoisting cable comprises one or more first suspension cable parts (36a) extending between the object suspension device and a radially outward location of the boom, and one or more second suspension cable parts (36b) extending between the objection suspension device and a radially inward location, such that the first and second suspension cable parts extend at V-shape with respect to each other, at an angle of preferably between 20 and 60°.