Vessel Speed-Through-Water Estimation Using Hydrodynamic Modeling
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Solution Overview
Problem
Conventional methods for measuring the speed through water (STW) of marine vessels are plagued by high noise levels, erratic behavior, and calibration issues, especially in environments with low water impurities, and often rely on inaccurate approximations or multiple data sources prone to errors.
Innovation Solution
A sensor system that combines propeller revolutions per minute, torque, propulsion power, thrust, engine fuel consumption, and speed over ground data with hydrodynamic modeling to determine STW, utilizing logged data and oceanographic current forecasts for enhanced accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler Log is used to measure STW, then speed measurement capability is provided, but measurement precision deteriorates due to high noise levels and calibration errors
Solution Approach 1:
The patent introduces an intermediary computational model that processes multiple input parameters (RPM, torque, power, fuel consumption, SOG) to derive STW. This intermediary processing layer filters out the noise and calibration errors that directly affect Doppler Log measurements, providing a more reliable and precise STW measurement through mathematical relationships rather than direct sensing.
Solution Approach 2:
The patent creates a multi-functional measurement system that uses a single integrated approach to simultaneously determine STW, assess hull fouling, and evaluate propeller performance. By combining multiple data sources (RPM, torque, power, fuel consumption, SOG) into one unified measurement framework, the system achieves universal applicability for various vessel performance assessments without relying on separate specialized sensors.
2Measurement precision
If Doppler Log is used to measure STW, then speed measurement is achieved, but device complexity increases due to calibration requirements and environmental dependencies
Solution Approach 1:
The patent extracts the essential measurement capability from complex calibration-dependent systems. By taking out the core physical relationships (power-RPM-STW connections) and formalizing them into a computational model, the system eliminates the need for frequent calibration procedures and reduces dependency on environmental conditions, while maintaining the ability to measure STW accurately.
Solution Approach 2:
The measurement system performs self-calibration and self-validation by using internally consistent relationships between measured parameters. The system uses the interconnections between RPM, torque, power, and fuel consumption to automatically verify and adjust measurements without requiring external calibration references or multiple independent data sources, thereby reducing operational complexity.
3Device complexity
If approximation based on propeller RPM alone is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent merges multiple measurement parameters (RPM, torque, power, fuel consumption, and SOG) into a unified STW determination framework. By combining these parameters through hydrodynamic modeling, the system achieves high measurement precision while maintaining practical device complexity levels, as all inputs can be obtained from standard vessel monitoring systems.
Data Source
AI summary
Disclosed are a method and a virtual sensor system for determining the speed through water of a marine vessel. The method includes obtaining propeller revolutions per minute and at least one of torque at propeller, propulsion power, thrust and engine fuel flow, obtaining speed over ground or logged data from one or more speed through water logs of the vessel and using the obtained data and hydrodynamic modelling to determine the speed through water of the vessel.