Vessel Heave Compensator Arm for Mooring Cable Force Reduction
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Solution Overview
Problem
Existing mooring systems for vessels face challenges in efficiently connecting submerged structures while minimizing the impact of heave movements, which can result in large forces on lifting cables and require significant deck space for heave compensators.
Innovation Solution
A compact heave compensator design featuring a pivoting arm and displacement device aligned with the lifting trajectory, reducing cable losses and heat generation, and allowing for efficient heave compensation with reduced space requirements, enabling rapid and controlled connection of submerged structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional heave compensator is used to compensate for vessel heave movements during mooring operations, then the lifting cable is protected from excessive forces, but the device requires significant deck space and adds complexity to the system
Solution Approach 1:
The patent combines the heave compensation function with the mooring connection operation itself. The compensator arm integrates the heave compensation mechanism directly into the mooring system, eliminating the need for a separate deck-mounted heave compensator. This merging of functions reduces deck space requirements while maintaining cable protection capabilities
Solution Approach 2:
The compensator arm serves multiple functions: it provides heave compensation, guides the lifting cable, and assists in the mooring connection operation. This multi-functionality eliminates the need for separate dedicated heave compensation equipment, thereby reducing overall system complexity and deck space occupation
2Power
If a high-capacity winch is used to lift the buoy against large heave-induced forces, then the lifting capacity is sufficient, but the winch requires significant deck space and generates large forces on the lifting cable
Solution Approach 1:
The compensator arm acts as a mechanical counterbalance system that offsets the weight and forces generated during buoy lifting. By providing passive mechanical counterbalancing through the arm's geometry and pivot mechanism, the system reduces the active lifting force required from the winch, allowing for a smaller, more space-efficient winch design
Solution Approach 2:
The compensator arm provides dynamic adaptation to heave movements through its pivot mechanism, automatically adjusting to vessel motions without requiring high-capacity active lifting systems. This dynamic response reduces peak forces on the lifting cable and allows for reduced winch capacity while maintaining effective lifting capability
3Stability of the object's composition
If the heave compensator is deactivated during buoy connection to prevent relative motion, then connection stability is improved, but large forces act on the pickup cable and winch
Solution Approach 1:
The compensator arm is pre-positioned and ready to provide mechanical support before the buoy connection is finalized. The arm's geometry is designed to provide immediate mechanical advantage during the connection phase, allowing the system to maintain stability while reducing cable forces through passive mechanical support rather than requiring full active heave compensation
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 solution effectively reduces forces exerted by heave movements on lifting cables, extends the lifespan of cables, and optimizes deck space usage, enabling efficient and controlled lifting of heavy subsea structures with high lifting capacity.
Implementation Method 1
a pivoting arm and displacement device aligned with the lifting trajectory, reducing cable losses and heat generation
Implementation Method 2
A compensator arm with a pivot end pivotally connected to a pivot point on the vessel
Implementation Method 3
a lifting cable attached to the lifting device and extending along a heave compensating member on the vessel and along a substantially vertical lifting trajectory
Implementation Method 4
the arm being at or near the free end connected to the displacement device
Data Source
AI summary
A vessel has a hull, a contact area at the hull near keel level for attaching to a structure, a lifting device and a lifting cable attached thereto and extending along a heave compensating member. The lifting cable extends along a substantially vertical lifting trajectory to a connect position below keel level. The heave compensating member includes a guide element for guiding the lifting cable and which is connected to a displacement device. The heave compensating member includes a compensator arm with a pivot end pivotally connected to a pivot point on the vessel at a predetermined transverse distance from the lifting trajectory, the cable guide element being attached to a free end of the compensator arm at or near the lifting trajectory, guiding the lifting cable in the direction of the pivot point, the arm being at or near the free end connected to the displacement device.