A system, comprising: a drum submerged in water and extending horizontally along a center axis between a first point on a first side of the drum and a second point on a second side of the drum opposite the first side; exactly three curved vanes attached to the drum such that the vanes, when acted upon by a water flow perpendicular to the center axis, are operable to cause rotation of the drum about the center axis, and wherein a cross-section of each vane includes a concave side and a convex side, the convex side curved differently than the concave side, such that: 1) the concave side of one vane meets the convex side of a neighboring vane at the drum in a smooth, substantially linear transition from the concave side of the one vane to the convex side of the neighboring vane, 2) each vane is more narrow at a tip end opposite the drum as compared to a root end at the drum, and 3) an edge portion of each vane, located substantially opposite the drum, defines a plane substantially parallel to a plane defined by a surface of the drum located between the edge portion and the center axis; a flow deflector submerged with the drum to direct at least some of the water flow into an area defined by a vane; and an electrical generator coupled to the drum to convert rotational energy produced by the rotation about the axis into electrical energy, wherein the system operates in various water flow speeds ranging from 0.44704 meters per second (1 mile per hour, MPH) to over 8.9408 meters per second (20 MPH), and further wherein rotation of the drum generates either an upward or downward force on the drum within the water. a drum submerged in water and extending horizontally along a center axis between a first point on a first side of the drum and a second point on a second side of the drum opposite the first side; exactly three curved vanes attached to the drum such that the vanes, when acted upon by a water flow perpendicular to the center axis, are operable to cause rotation of the drum about the center axis, and wherein a cross-section of each vane includes a concave side and a convex side, the convex side curved differently than the concave side, such that: 1) the concave side of one vane meets the convex side of a neighboring vane at the drum in a smooth, substantially linear transition from the concave side of the one vane to the convex side of the neighboring vane, 2) each vane is more narrow at a tip end opposite the drum as compared to a root end at the drum, and 3) an edge portion of each vane, located substantially opposite the drum, defines a plane substantially parallel to a plane defined by a surface of the drum located between the edge portion and the center axis; a flow deflector submerged with the drum to direct at least some of the water flow into an area defined by a vane; and an electrical generator coupled to the drum to convert rotational energy produced by the rotation about the axis into electrical energy, wherein the system operates in various water flow speeds ranging from 0.44704 meters per second (1 mile per hour, MPH) to over 8.9408 meters per second (20 MPH), and further wherein rotation of the drum generates either an upward or downward force on the drum within the water.