Simulation of a marine dynamic positioning system equipped with cycloidal propellers

Marine cycloidal propellers represent a good alternative to traditional propellers especially in Dynamic Positioning (DP) applications, since they can generate almost the same thrust in all directions. The present study aims to combine a simulation platform, previously developed by some of the authors for DP systems, with the performance modelling of an epicycloidal propeller. The latter bases the propeller thrust and torque evaluation on the kinematics of the blades, taking into account suitable correction factors in order to consider the interference phenomena among blades. As a case study, the control and allocation logics of a DP system are analyzed for a surface vessel, equipped with a single bow thruster and two epicycloidal propellers at stern. The examined ship is the same for which a DP system, characterized by a conventional twin-screw propulsion, was already studied and installed on board. A performance comparison between the two distinct propulsion configurations is then carried out by dynamic simulation.