If the paddles of a waterwheel are rotated as in the animation above, the paddles can enter the water at just below the axle level - resulting in around half the waterwheel in the water, and half out. This then allows for the waterwheel to be floated with a barge on either side, making it possible to place it within the fastest flow of rivers or tidal currents.
In a standard undershot waterwheel, the paddles are fixed. If the paddles enter the water at 45° then for every 1m of waterwheel in the water, there will be 5.8m out of the water, which requires construction works to support the wheel. This was fine in the days when a shaft was taken from the wheel to run machinery, but for the generation of electricity the waterwheel no longer needs to be placed next to the machinery.
The rotation of the paddles on the prototype is achieved by using sprocket and chain - a small fixed sprocket at the centre, and a larger sprocket with twice the number of teeth at the end of each paddle results in each paddle making a half turn for one full turn of the waterwheel.
The power of moving water can be calculated using the formula:
Power=½ x density x area x (water speed)³
With water flowing at 3m/s (around 6 knots), this results in 13.5kW for each square metre (of paddle).
This figure is impossible to achieve, but with an efficiency of 0.3 you could still get 4kW per square metre.
To see some footage of our test conducted near Norwich on 7 April 2006 where the waterwheel was dragged along the side of the boat, click on the link bleow. If clicking on the link below doesn't work: come back to this page, right click on the link below and select "Save Target As...", save the file to your computer and run from there. tomswheel.mpg(4.6Mb)
Master craftsmen
Film Credits
Leading Actor: Tony
Supporting Cast: Tom & Mark
Director: Daniel
Camera: Daniel
Sound: Daniel
Set Builder: Daniel
Set Assistant: Mark
Set Designer: Tom
For more information contact Tom on +44 (0) 7798834289
