For avoiding a high permanent load of the main and control drives rotatable around the vertical axis for ships for the straight forward sailing by a small and compact course keeping rudder system provided for this purpose, for a propulsion system (10) for ships, in particular for cruise vessels (100) with combined main and control drives (20), in particular with at least one podded propulsor (25; 25'), whereby the drive and at least one propeller (26; 26') are combined in a rotatable gondel-type unit or gondel-type housing (27) placed outside the proper hull (110) in the stern area (115), at least one course keeping rudder system (30; 30') is placed outside the swivelling range of the podded propulsor (25) or of the podded propulsors (25; 25') in the stern area (115) of the hull (110) as an independent, separate, small and preferably electrohydraulically driven rudder configured with a flow favourable profile which makes available only the steering moments necessary for the ship during the straight forward travelling, preferably under course control operation (or autopilot operation), the main and control drives being unused during the straight forward travelling, no longer used and remaining in inoperative position.