A water turbine having a waterwheel, the waterwheel having rotor blades, the water turbine having an input shaft (1701,1820) connected to the waterwheel and providing a variable rotational speed input, the input shaft turned by the waterwheel at a rotational velocity determined by water flow and direction, the water turbine having an output shaft connected to a constant speed generator, the water turbine further comprising a hatch for varying the portion of the waterwheel exposed to receive water dependent on water flow to the waterwheel; the water turbine having a gear box connected between the waterwheel and the constant speed generator for driving the constant speed generator at a constant rotational speed, the water turbine having a first spur gear assembly and a second spur gear assembly provided on the input shaft, the spur gear assemblies providing a rotational velocity control for providing constant frequency output of the constant speed generator for generating electricity, each of the spur gear assemblies comprising: a first sun gear connected to or integral with the input shaft of the turbine, the input shaft entering and exiting a first housing for the first spur gear assembly; a second sun gear connected to or integral with a sleeve surrounding a portion of the input shaft; and a first planetary gear (1703-2,1703-4) engaging with the first sun gear; and a second planetary gear (1703-1,1703-3) engaging with the first planetary gear (1703-2,1703-4) and with the second sun gear; wherein the first and second planetary gears (1703-2,1703-4; 1703-1,1703-3 are mounted on a carrier (1708,1709) rotatably mounted on the input shaft; wherein the water turbine further comprises a first worm and a worm gear assembly (1918,1922) contained in the first housing and coupled to a hatch gear for controlling the hatch to vary the portion of the waterwheel exposed to receive water dependent on water flow, the opening and closing of the hatch being controlled between a minimum and a maximum rated rotational speed of the waterwheel, the second spur gear assembly having a large diameter control gear connected to or integral with the sleeve of the first spur gear assembly for control of the first worm and worm gear assembly for closing the hatch and having a carrier gear and a pin for control by the first worm and worm gear assembly for opening the hatch, the waterwheel rotational velocity thereby being maintained between minimum and maximum rated rotational speeds. the water turbine having an output shaft connected to a constant speed generator, the water turbine further comprising a hatch for varying the portion of the waterwheel exposed to receive water dependent on water flow to the waterwheel; the water turbine having a gear box connected between the waterwheel and the constant speed generator for driving the constant speed generator at a constant rotational speed, the water turbine having a first spur gear assembly and a second spur gear assembly provided on the input shaft, the spur gear assemblies providing a rotational velocity control for providing constant frequency output of the constant speed generator for generating electricity, each of the spur gear assemblies comprising: a first sun gear connected to or integral with the input shaft of the turbine, the input shaft entering and exiting a first housing for the first spur gear assembly; a second sun gear connected to or integral with a sleeve surrounding a portion of the input shaft; and a first planetary gear (1703-2,1703-4) engaging with the first sun gear; and a first sun gear connected to or integral with the input shaft of the turbine, the input shaft entering and exiting a first housing for the first spur gear assembly; a second sun gear connected to or integral with a sleeve surrounding a portion of the input shaft; and a first planetary gear (1703-2,1703-4) engaging with the first sun gear; and a second planetary gear (1703-1,1703-3) engaging with the first planetary gear (1703-2,1703-4) and with the second sun gear; wherein the first and second planetary gears (1703-2,1703-4; 1703-1,1703-3 are mounted on a carrier (1708,1709) rotatably mounted on the input shaft; wherein the water turbine further comprises a first worm and a worm gear assembly (1918,1922) contained in the first housing and coupled to a hatch gear for controlling the hatch to vary the portion of the waterwheel exposed to receive water dependent on water flow, the opening and closing of the hatch being controlled between a minimum and a maximum rated rotational speed of the waterwheel, the second spur gear assembly having a large diameter control gear connected to or integral with the sleeve of the first spur gear assembly for control of the first worm and worm gear assembly for closing the hatch and having a carrier gear and a pin for control by the first worm and worm gear assembly for opening the hatch, the waterwheel rotational velocity thereby being maintained between minimum and maximum rated rotational speeds.