Abstract: A Savonius vertical axis wind turbine rotor has first and second curved vanes having remote substantially vertical edges widely spaced form each other, and proximate substantially vertical edges more closely horizontally spaced from each other and horizontally overlapping are associated with a substantially vertical central shaft construction. The shaft construction is operatively connected to the vanes and mounts the vanes and adjacent the proximate edges. The central shaft construction may comprise a perforated shaft (e.g. a single perforated shaft), or multiple shafts. In any event, the shaft construction, and mounting of the rotor vanes, allow, during use, spillover of wind from the proximate edge of one vane to another vane during powered rotation of the vanes in response to wind. The rotor is preferably omni-directional. The rotor may have a third set of vanes, and different vertically spaced sets of vanes circumferentially offset with respect to each other.