A number of embodiments of water powered devices that are adapted to be positioned in a stream of moving water and which carry water wheels for driving a driven device. The driven device may comprise a generator and a number of embodiments are illustrated for holding the generator against rotation and for absorbing its torque loading. In addition, a device is provided for insuring buoyancy of the device so that the water wheels float with their axis above the level of water. In some embodiments, the buoyant device comprises a buoyant float that also provides a hydrodynamic lift and a hydrodynamic force for carrying the device to the center of the stream. In other embodiments, the device comprises a hydrodynamic device that provides both the lift and the transverse force. An arrangement is disclosed which permits stacking of the water wheels for ease of packing and additionally an arrangement is disclosed for permitting replacement of individual blades of the water wheels. Various ganging arrangements are also disclosed.