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The advantages
of the propeller can be extended to watercraft intended for less rapid
transportation than a racing machine. The Dorey shown has a recumbent bike
pedal system coupled to a stern propeller. The vessel weighs 1,300 N and
a waterline length of 3.96 m. In smooth water a speed of 4 knots can be maintained
for about an hour. The vessel was designed by Philip Thiel, a Seattle
naval architect, to be sea worthy and load carrying.
The disadvantage
of a propeller is its propensity to fouling and hitting the bottom in shallow
water. It also makes the boat less maneuverable as forward speed is required
for the rudder to be effective. A steerable propeller would solve this problem
at the expense of mechanical complexity. |
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From:
Abbott, Brooks and Wilson,
Human-Powered Watercraft,
"Human-Powered
Vehicles," Human Kinetics (1995) |
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