Influence of propeller fouling on propulsion performance of an actual ship: a long-term analysis focusing on the power for keeping propeller’s rotation of a controllable pitch propeller

Abstract

This study focuses on the shaft power at the neutral angle of a controllable pitch propeller to analyze the change in the required power due to propeller fouling. It is named and defined as a power for keeping propeller’s rotation (RP) because a propeller does not generate the net thrust to push the hull but dissipates the power to keep its constant speed. Statistical analysis was conducted using a decade of the observed data from a research vessel. This study assumed that the change in RP can be considered as an indicator showing the state of propeller fouling. In addition, the state of fouling on the hull can be estimated indirectly based on RP because the data correlated the shaft power under several operating conditions with RP on the same voyage. The fouling state was classified into three conditions based on RP. The comparison of shaft power at the same ship speed between the clean condition and the serious fouled condition showed that the shaft power was increased by 35% on average due to fouling. When the ship navigates under 10 knots, propeller fouling has a larger impact on the increase in shaft power than hull fouling.