A rudder propeller including a drive shaft and a propeller shaft that can be driven by the drive shaft by an angular drive and a planetary gear that can be located on the propeller shaft and including a sun gear that is connected to the angular drive via a coupling, a fixed ring gear and planet gears that revolve between the sun gear and ring gear and that are mounted on a planet carrier. The planet carrier can be secured against torque to the propeller shaft and the coupling between the angular drive and the sun gear can be designed as a double cardanic, rotationally-fixed flexible coupling, in such a way that radial and angular displacements of the sun gear in relation to the angular drive can be compensated.