Assessment of the Efficiency of a Mewis Duct Through Performance Analysis of Operational Data

Abstract

The efficiency of a Mewis propeller duct by the analysis of ship operational data is examined. The analysis employs data collected with high frequency for a three-year period for two siter vessels, one of them fitted with a Mewis type duct. Our approach to the problem of identifying improvements in the operational performance of the ship equipped with the duct is two-fold. Firstly, we proceed with the calculation of appropriate Key Performance Indicators to monitor vessels performance in time for different operational periods and loading conditions. An extensive pre-processing stage is necessary to prepare a dataset free from datapoints that could impair the analysis, such as outliers, as well as the appropriate preparations for a meaningful KPI calculation. The second approach concerns the development of multiple linear regression problem for the prediction of main engine fuel oil consumption based on operational and weather parameters, such as ship’s speed, mean draft, trim, rudder angle and the wind speed. The aim is to quantify reductions due to the Mewis duct for several scenarios. Key results of the studies reveal a contribution of the Mewis duct mainly in laden condition, for lower speed range and in the long-term period after dry-docking.

Keywords

Performance monitoring / Energy saving device / Regression models / Data processing / Mewis duct

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