A propulsion mechanism (100) for a maritime vessel (200) including a rotor (75) mounted for rotation about a rotor axis. The rotor (75) includes a plurality of vanes (20) extending essentially radial to the rotor axis and the vanes are arranged to define spaces (25) in between the vanes (20). The propulsion mechanism (100) further includes means configured for freeing the spaces (25) of water by means of application of air.