Maneuvering simulations at large drift angles of a ship with a flapped rudder

Abstract

In this paper, a simulation method is presented for calculating the ship maneuvering motions at large drift angles, including acceleration turning and stopping. For the ship hull force model, a method to use directly the hydrodynamic force data at large drift angle conditions without a mathematical expression is employed. The hydrodynamic forces are obtained using captive model tests. The rudder force is modeled based on existing tank test results. The present models are applied to the maneuvering simulations for an inland container ship equipped with a bow thruster and flap rudder. In addition to the ordinary maneuvering motions such as turning and zig-zag maneuvers, the low-speed maneuvering motions such as acceleration turning by steering, acceleration turning using the bow thruster, and propeller reverse stopping are simulated. The simulation results are compared with the free-running model test results to validate the present method. As a result, we found that the present method can simulate not only ordinary maneuvering motions but also low-speed maneuvering motions with a large drift angle with practical accuracy.