A rotor (10) for a hydro-powered electricity generator. The rotor (10) includes a hub (12) and a plurality of blades (16). The hub (12) has a circular cross sectional shape and a longitudinal rotational axis (14). The plurality of blades (16) each have proximal root (16a) and a distal tip (16b). Each of the blade roots (16a) are mounted to the hub (12) at the widest part thereof (D1). The ratio between the diameter of the tips (16b) of the blades to the diameter of the widest part (D1) of the hub (12) is less than about 2:1.