Abstract
The propulsion efficiency of a ship is affected by the fouling of the propeller and ship's hull surface. Fouled surfaces decrease the propulsion efficiency of a ship, and consequently main engine fuel consumption; this increase is due to the torque-rich condition of the main engine.It is well understood that the coating on a propeller and on a hull can protect the propeller and hull surfaces from fouling. It enables us to maintain the service speed of the ship over long periods. Marine engineers check also periodically note the rpm margin of engine output. In the T.S KAIGI-MARU, three kinds of surface treatment were applied during dry docking and over three years. To determine the most effective treatment, three different kinds were employed, for maintaining high propulsion efficiency. The data was then collected for the rpm margin.In this paper, the fouled conditions of the propeller and hull surfaces were estimated by analyzing the rpm margin, so in order to find the optimum Dry Dock Time.
