Abstract
The current work investigates, both with model tests and numerical calculations, the forces and turning moments experienced by a single-screw ship model in reversing mode. Model tests were carried out by Marintek, in the large towing tank of the Marine Technology Center in Trondheim, on a chemical tanker model. RANS calculations were then carried out also considering additional conditions with respect to the model tests. The ship length was also modified in order to investigate how this parameter, as well as ship speed and propeller loading, can affect the forces and moments experienced by the model. The main goal was to provide data and physical understanding about the hydrodynamic reasons which prevent a reversing single-screw ship from traveling straight backward, determining, instead, a side rotation. A complementary scope was to develop a simplified model suited for implementation in a real-time ship simulator.