A propelling and driving system for boats having an outboard rudder propeller. The system provides the boat with reliable and comparatively good maneuverability. The system comprises at least two rudder propellers, each having driving motors configured in the form of a permanent magnet-excited synchronous machine. The stator winding of each synchronous machine has three winding phases connected to a three-phase alternating current, which are connected to the supply system of the boat. A modular controlling and regulating device comprising standardized modules is provided for each of the rudder propellers.