A CRASH-STOP STUDY FOE AN AZIPOD-PROPELLED VESSEL

摘要

This paper presents investigations into the crash stop manoeuvre for a ship propelled by two AZIPOD electric propulsion units by. The manoeuvre is executed by turning the pods through 0° to 180° without reversing the propellers. The authors consider two options: turning the pods simultaneously outwards or inwards relative to the centreline. To achieve the task, the authors have used model tank data: propeller thrust and torque in the presence of the pod and the lateral force on the propulsion system (propeller+pod) within the entire range of its turning angles. The ship stopping distance and time were estimated. Additionally, assessments included maximum hydrodynamic forces applied to the propeller at crash stopping, and the strength of the propeller blades. It is demonstrated that compared to the traditional crash stop (propeller reversing), the alternative technique enables to significantly reduce both the stopping distance and the stopping time. In order to ensure accident-free propeller operation, investigations also covered the effects of the pod turning rate and of the torque delivered to the propeller upon the maximum load acting on the propeller during the crash stop manoeuvre.