A disconnectable mooring system for a vessel comprises a mooring buoy member and a turret structure mounted in a moonpool of the vessel. The mooring buoy member is anchored to the seabed and has a plurality of passages each adapted to receive a riser. The turret structure has a receptacle for receiving the buoy member and a locking device for locking the buoy member in the receptacle. The turret structure accommodates a plurality of conduits to be connected to risers installed in passages of the buoy member and the turret structure is rotatably supported in the moonpool of the vessel by at least a bearing assembly mounted above sea level. The buoy member is provided with a conical outer casing and the receptacle of the turret structure has a cone shape corresponding to the conical outer casing of the buoy member. The turret structure comprises a turntable carrying the conduits to be connected to the risers. The turntable is supported on the bearing assembly in a manner allowing rotation with respect to the turret structure to align the conduits with the risers when the buoy member is received and locked in the receptacle of the turret structure. Additionally or alternatively, each conduit may comprise a lower part movable with respect to the turret structure to align the lower part with the corresponding riser.