Semi-Submersible Service Vessel Hull Draft Control
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Solution Overview
Problem
Current maintenance methods for offshore wind turbines are inefficient, as they require calm weather for towing and can be unstable during service operations due to movement from wind and waves, limiting operational windows.
Innovation Solution
A semi-submersible service vessel with a ballasting system and submersed elongate lifting forks that adjust draft to securely engage and lift offshore installations, maintaining stability and allowing maintenance in varying weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a service vessel is fixed to the floating wind turbine during maintenance, then the wind turbine can be serviced, but the wind turbine becomes unstable and can dismount during heavy seas
Solution Approach 1:
The service vessel is divided into two operational states: a first draft position for stable transport and positioning, and a second elevated draft position for secure engagement with the floating wind turbine. This segmentation allows the vessel to optimize its characteristics for each specific function.
Solution Approach 2:
The service vessel employs a dynamic ballasting system that can adjust its draft between two states. By pumping water between ballast tanks, the vessel transitions from a lower draft (stable for positioning) to a higher draft (engaged with turbine), adapting its physical characteristics to operational requirements.
2Speed
If towing is used to transport the floating wind turbine to harbour, then the turbine can be moved, but calm weather conditions are required which increases time consumption
Solution Approach 1:
The service vessel acts as an intermediary platform between the floating wind turbine and the harbour. Instead of towing the turbine directly to harbour, the vessel engages with the turbine, transports it to a controlled position, and provides a stable platform for maintenance operations at sea.
Solution Approach 2:
The service vessel performs preliminary positioning and stabilization of the floating wind turbine before maintenance operations begin. By securing the turbine to the vessel and positioning it in optimal conditions, the vessel prepares the system for efficient maintenance without requiring harbour towing.
3Adaptability or versatility
If the service vessel operates in heavy seas, then more operational windows are available, but the floating wind turbine becomes unstable due to wind and wave movement
Solution Approach 1:
The service vessel uses its ballast system as a counterbalancing mechanism. By adjusting its draft and position relative to the floating wind turbine, the vessel creates stabilizing forces that counteract the effects of wind and waves, maintaining system stability even in rougher sea conditions.
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
Enables stable and efficient maintenance of offshore wind turbines by securely lifting and stabilizing the installation, reducing downtime and operational constraints related to weather conditions.
Implementation Method 1
a ballasting system arranged to selectively lower the hull to a first draft and raise the hull to a second draft
Implementation Method 2
at least one submersed elongate lifting fork fixed to the hull and configured to extend across the underside of the floating installation and engage the underside of the floating installation
Data Source
AI summary
A semi-submersible service vessel (100) for a floating installation (102) has a hull (104) and a ballasting system. The ballasting system is arranged to selectively lower the hull (104) to a first draft and raise the hull (104) to a second draft. The second draft is smaller than the first draft. At least one submersed elongate lifting fork is fixed to the hull (104) and is configured to extend across the underside of the floating installation (102) and engage the underside of the floating installation (102) when the hull (104) is raised from the first draft to the second draft. Wherein the at least one lifting fork is arranged to lift the entire floating installation (102) when the hull (104) is raised from the first draft to the second draft, and a method of servicing a floating installation (102) with a semi-submersible service vessel (100).