A propulsion system (102) for an aquatic vessel (100) is provided. The propulsion system includes a plurality of Magnus-type rotors (108) and a drive arrangement (147) for rotating the plurality of Magnus-type rotors. The plurality of Magnus-type rotors are operable to rotate about corresponding substantially upright axes. The propulsion system also includes a control arrangement (150) for controlling the drive arrangement to vary rates of rotations of the plurality of Magnus-type rotors. Each of the plurality of Magnus-type rotors includes a hollow region (116) therein. Each of the Magnus-type rotors is rotationally supported onto a support arrangement (118) which extends into the hollow region. The drive arrangement includes at least one motor (148) disposed in the hollow region and located outside the support arrangement such that the at least one motor is accessible for maintenance. Furthermore, the at least one Magnus-type rotor includes a ventilation aperture arrangement (132) for enabling an upward movement of air to occur in operation within the at least one Magnus-type rotor for ventilating and cooling the drive arrangement and/or other internal components.