Pontoon-Coupled Extension Plates for Offshore Platform Heave Damping
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Solution Overview
Problem
Existing offshore semi-submersible platforms face challenges in stabilizing movement due to wave and wind action, with existing heave plates facing rigidity issues and requiring deep drafts that complicate installation and operation, especially in harsh sea states.
Innovation Solution
The integration of extension plates coupled to pontoons on the offshore platform, which separate water and create drag, increasing dynamic mass and natural periods of motion to reduce heave motion, without the need for extending legs, and can be installed during fabrication to maintain clearance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If heave plates are mounted deeper to reduce heave motion, then platform stability is improved, but installation complexity and operational difficulty increase due to deep draft requirements
Solution Approach 1:
The extension plates extend horizontally outward from the pontoon in a lateral direction rather than requiring vertical depth extension. This dimensional shift allows the heave-damping function to be achieved through horizontal surface area increase rather than vertical draft increase, simplifying installation while maintaining stability improvement.
Solution Approach 2:
The extension plates are integrated into the pontoon structure during fabrication at the yard before the platform is towed to the offshore site. This preliminary integration eliminates the need for complex deep-water installation operations and allows the platform to maintain operational clearance during transit and installation.
2Force
If heave plates are made larger to increase hydrodynamic mass, then heave resistance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The heave-damping function is segmented into multiple extension plates attached to different pontoons rather than requiring a single large complex structure. Each extension plate is a simple flat element that collectively provides the required hydrodynamic mass and resistance when combined with other plates on the platform.
Solution Approach 2:
The extension plates serve multiple functions: they increase the effective surface area for heave damping, add hydrodynamic mass, and can be integrated into the existing pontoon structure without requiring separate complex mounting systems. This multi-functionality reduces overall device complexity while achieving the force resistance goal.
3Stability of the object's composition
If legs are extended to reduce heave motion, then platform stability is improved, but operational clearance is reduced and installation becomes more difficult
Solution Approach 1:
Instead of extending the overall platform draft uniformly through longer legs, the extension plates add local surface area specifically at the pontoon level where heave motion occurs. This localized addition provides heave resistance without increasing the overall vertical draft, thereby maintaining operational clearance while improving stability.
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
This solution effectively reduces platform movement and wave-driven motion, enhancing stability and reducing the risk of offshore installation challenges by increasing the natural period of heave motion and damping wave loads, while maintaining operational clearance.
Implementation Method 1
the pontoon-coupled extension plates separate the water and cause drag on the platform in the direction of movement
Implementation Method 2
The heave plate increases the hydrodynamic mass of the offshore platform, where hydrodynamic mass is a measure of the amount of a fluid moving with a body that accelerates in the fluid
Implementation Method 3
The added dynamic mass increases the natural period of the motion away from the wave excitation period to minimize the wave driven motion
Implementation Method 4
The heave plate at the lower depths provides additional resistance to vertical and tilting motion that would otherwise occur near or at the water surface
Data Source
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Figure 5~6A
AI summary
A floating offshore platform is disclosed with one or more extension plates fixedly coupled to one or more pontoons on the offshore platform and extending from the pontoons. As the floating platform moves, the pontoon-coupled extension plates separate the water and cause drag on the platform. The water moving with the extension plates also increases the dynamic mass. The added drag and dynamic mass increases the natural period of the motion away from the wave excitation period to minimize the wave driven motion compared to a platform without the extension plates. The extension plates can be coupled to the pontoons during fabrication at the yard directly or through frame members. The extension plates generally are generally located inclusively between the top and bottom elevations of the pontoons, and therefore do not significantly reduce the clearance between the seabed and the hull at the quayside.