Remote Propeller Fouling Detection via Coasting Maneuver Analysis
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Solution Overview
Problem
Current methods for detecting propeller fouling in marine vehicles are cumbersome, costly, and lack accuracy, particularly in measuring advance velocity, propeller shaft torque, and distinguishing between hull and propeller fouling effects.
Innovation Solution
A method involving an 'inertia stop' or 'coasting' maneuver, where the propeller power is cut, and the revolutions per unit time are recorded and compared to a nominal relation to assess fouling, using parameters like Nq,s and arithmetic differences to quantify fouling levels, allowing for remote detection without relying on costly measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods are used to measure advance velocity and propeller shaft torque, then measurement accuracy may be improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts the essential measurement requirement from complex direct measurement systems. Instead of measuring advance velocity and shaft torque directly with complex sensor systems, the invention extracts only the necessary information (propeller revolutions vs. time relationship) that can be obtained through a simpler coasting maneuver test, eliminating the need for complex measurement apparatus while retaining the ability to assess propeller fouling.
Solution Approach 2:
The patent creates a simplified copy of the propeller's operational characteristics by performing a coasting maneuver that replicates the essential dynamics of propeller deceleration. This copy (the deceleration curve during coasting) contains the same diagnostic information about propeller fouling as full-power operation would provide, but can be obtained with much simpler measurement equipment.
2Loss of information
If multiple sensors are deployed to measure thrust, torque, rotational speed, and speed through water, then measurement completeness is improved, but ease of operation deteriorates
Solution Approach 1:
The patent extracts only the essential measurement needed for propeller fouling assessment - the relationship between propeller revolutions and time during coasting. This extraction eliminates the need to deploy multiple sensors for thrust, torque, and speed measurements, simplifying the operational procedure while retaining sufficient information to detect propeller fouling through comparison with nominal deceleration characteristics.
3Loss of information
If conventional fouling detection methods are used, then comprehensive data collection is improved, but productivity decreases due to time-consuming procedures
Solution Approach 1:
The patent implements a periodic coasting maneuver test that can be performed at regular intervals to assess propeller fouling. This periodic action provides sufficient data to detect fouling trends over time without requiring continuous complex measurements, thereby improving detection efficiency and productivity while maintaining adequate information collection for assessing propeller condition.
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 accurate and remote detection of propeller fouling, reducing operational costs and improving measurement accuracy, while also allowing for the detection of other propeller damages.
Implementation Method 1
When performing a coasting maneuver, the propeller acts as a water turbine
Implementation Method 2
the propeller rotates due to inertia of the rotating mass
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Method and device of detecting the fouling of a propeller mounted to a vessel 10 and connected to a main engine providing power to the propeller 14. The method includes comparing the relation of revolutions per unit time of the propeller vs. time obtained during a coasting maneuver in actual conditions and a corresponding curve obtained while performing a coasting maneuver with the propeller with no fouling. Assessment of the fouling level of the propeller 14 is based on this comparison. With the present method it is possible to detect the condition of the propeller 14 remotely, without relying on values of the performance that are cumbersome and costly to measure.