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Note: ESDATSEA

Abstract: This paper presents a method to quickly calculate the rudder forces including the interaction between rudder and propeller. The presented method couples and enhances two existing methods for the calculation of propeller and rudder forces. Since the method should be applied in the early design stage, the used methods need to be quick and therefore they both base on the potential theory. Firstly, the interaction between the different lifting surfaces is calculated iteratively with a lifting line approach, where each device is described by a lifting line. Afterwards, these results are used as initial values in a three dimensional panel method. After calculating the setup in the panel method, the results are used to improve the calculation of the lifting line. At the end, the pressure distribution on the rudder and the forces of the rudder are calculated using the panel method, whereas the forces and moments of the propeller are calculated with the lifting line. The paper presents results of the rudder-propeller interaction for the ahead condition in an exemplary case.