Offshore Crane Motion Compensation via Slewable Jib Beam
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Solution Overview
Problem
Existing wave-induced motion compensating cranes struggle to handle large loads at high lifting heights due to limitations in handling capacity and complexity, particularly when operating on offshore vessels for wind turbine installations or maintenance.
Innovation Solution
A wave-induced motion compensating crane design featuring a base structure, revolving superstructure, boom structure with a motion compensation device at the tip end, integrated heave compensation, and a control unit, allowing for controlled slew and linear motion of the jib beam to maintain load position and compensate for wave-induced motion, while minimizing the weight and complexity of the moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a jack-up type vessel is used to compensate wave-induced motion, then the vessel stability is improved, but the time required for setup and teardown is increased
Solution Approach 1:
The motion compensation function is segmented from the vessel structure itself and assigned to a dedicated crane system. The crane includes a base structure mounted on the vessel, a superstructure, and a motion compensation device with multiple degrees of freedom that can independently compensate for wave-induced motions without requiring the entire vessel to be jacked up.
Solution Approach 2:
The crane system transitions from a static, fixed-position structure to a dynamic, actively compensated system. The motion compensation device continuously adjusts the crane's position and orientation in real-time to counteract wave-induced vessel motions, enabling stable operation while the vessel remains floating.
2Stability of the object's composition
If the entire crane is positioned on a wave-induced motion compensated platform, then the crane stability is improved, but the platform weight and complexity are increased
Solution Approach 1:
The motion compensation functionality is extracted from the platform and integrated directly into the crane system. Only the necessary compensation mechanisms for the crane's specific operational requirements are implemented, rather than providing full platform-level compensation for the entire vessel.
Solution Approach 2:
The crane's boom and jib structures serve dual functions: both for lifting loads and for providing the mechanical basis of motion compensation. The motion compensation device utilizes the existing crane structure components to achieve stabilization, reducing the need for separate, dedicated compensation platform elements.
3Adaptability or versatility
If tip end portion compensation devices are used, then the crane adaptability is improved, but the handling capacity at high lifting heights is reduced
Solution Approach 1:
The motion compensation device is merged with the crane's boom and jib structures rather than being a separate attachment at the tip. The compensation mechanisms are integrated into the load-bearing structure, allowing the same components to handle both compensation functions and heavy lifting loads simultaneously.
Solution Approach 2:
The motion compensation system addresses all three spatial dimensions (heave, pitch, and roll) through coordinated movement of the base structure, superstructure, and jib beam. This multi-dimensional compensation approach maintains handling capacity at high lifting heights by distributing compensation actions across multiple structural elements rather than relying solely on tip-end adjustments.
Data Source
AI summary
A wave-induced motion compensation crane and corresponding vessel and method are disclosed. The crane includes a motion compensation device at a tip end portion of the boom structure to compensate for X-Y wave-induced motion and a heave compensation device for Z-motion. The motion compensation device includes a moveable jib beam that extends in a substantially horizontal direction. The jib beam is slewable about a substantially vertical slew axis and translatable in a longitudinal direction of the jib beam. Preferably, the jib beam can be levelled based on the angular orientation of the boom structure.