Self-Elevating Vessel Hull Motion Limits for Safe Leg Pulling
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Solution Overview
Problem
Current methods for self-elevating vessels during coming off location operations rely heavily on subjective human observations and generic wave forecasts, which can lead to unsafe conditions due to unpredictable environmental factors, potentially causing damage to the vessel during the transition from an elevated state to an afloat state.
Innovation Solution
A system utilizing onboard sensors and a control system to perform structural analyses and determine permissible operating ranges for hull motion, allowing for real-time monitoring and comparison against established limits, ensuring safe leg pulling operations by assessing actual environmental conditions and vessel responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subjective human observations and generic wave forecasts are used during coming off location operations, then the operation process is simple, but the safety and accuracy of structural assessment deteriorates
Solution Approach 1:
The patent replaces subjective human observations and generic wave forecasts with an automated control system that uses onboard sensors to measure actual environmental conditions (wave heights, periods, directions) and performs real-time structural analyses. This substitution of mechanical/manual assessment with automated sensor-based monitoring resolves the contradiction by providing reliable safety assessment without requiring complex manual judgment processes.
Solution Approach 2:
The system enables the vessel to self-monitor its own structural conditions during coming off location operations. The control system continuously assesses structural utilization ratios by comparing actual environmental measurements against predetermined permissible limits, allowing the vessel to autonomously determine when it is safe to lower from elevated state to afloat state without external intervention.
2Measurement precision
If real-time structural analysis and monitoring are implemented, then the accuracy of safety assessment is improved, but the device complexity and operational procedures increase
Solution Approach 1:
The control system is designed to perform multiple functions: it monitors positional displacement of the hull, measures environmental conditions (waves, wind), performs structural analyses, compares results against permissible limits, and provides safety recommendations. By consolidating these functions into a single multi-functional system, the patent achieves high measurement precision without proportionally increasing overall system complexity.
Solution Approach 2:
The system continuously monitors actual environmental conditions and vessel responses, then feeds this information back into the structural analysis process. The control system compares measured positional displacement and environmental parameters against predetermined permissible operating ranges, creating a closed-loop feedback mechanism that maintains high measurement precision while automating the complexity of continuous assessment.
3Reliability
If multiple structural analyses under different conditions are performed, then the reliability of safety determination is improved, but the time required for assessment increases
Solution Approach 1:
The patent performs preliminary structural analyses under various environmental conditions and vessel states before actual coming off location operations. Predetermined permissible operating ranges and structural utilization ratios are calculated in advance for different scenarios (elevated state, transitional state, afloat state). This preliminary preparation allows rapid real-time assessment during operations, improving reliability without increasing actual operational assessment time.
Solution Approach 2:
The system evaluates structural utilization under changing parameters (different wave heights, periods, directions, and hull draft levels) by comparing multiple condition sets. The control system efficiently processes these parameter variations by using predetermined analysis frameworks that can quickly adapt to current conditions, maintaining high reliability while minimizing the time required for comprehensive structural assessment.
Data Source
AI summary
A first permissible operating range of the self-elevating vessel is determined based on a first structural analysis of the self-elevating vessel under a first set of conditions. A structural utilization ratio of the self-elevating vessel is determined based on a second structural analysis of the self-elevating vessel under first and second sets of conditions. Safety of lowering the self-elevating vessel from an elevated state to a first hull draft level is determined when the structural utilization ratio is less than a predetermined value. Safety of lowering the self-elevating vessel from the first hull draft level to a second hull draft level is indicated when positional displacement data obtained while the vessel is at the first hull draft level indicates that the positional displacement of the self-elevating vessel while at the first hull draft level is within the first permissible operating range.