Investigation of the effectiveness of a stern foil on a patrol boat by experiment and simulation

In the marine industry, specifically fast patrol boats, the important objectives are reducing resistance and improving the efficiency of ships’ propulsion systems. The aim of this research was to investigate the application of a stern foil on a patrol boat through experimental and simulation methods. The stern foil used to generate a lift force was an asymmetrical National Advisory Committee for Aeronautics (NACA) foil. In the experiment, the stern foil was installed below the transom of a ship model and positioned parallel to the keel direction (3° towards x-axis). This position created a resultant force, which had an angle to the x-axis. There were variables in this experiment, such as the stern foil application, Froude number (Fr) and hull loads. Those combinations of variables generated sufficient data to analyse the effect of the stern foil working in various conditions. At an optimal load condition (half full load, 2 kg) and Fr 1.1 in the experiment and simulation, the ship model had a resistance reduction of as much as 22.3% and 23.3% in stern foil applications. In addition, with different setups of the stern foil (0° towards the x-axis) in the simulation, a resistance reduction of about 26.7% occurred at Fr 0.9.