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bilge pump as propulsion
Brian Whatcott wrote:
On Sun, 11 Feb 2007 07:33:28 -0800, R Swarts wrote: Should also have mentioned that my 30 lb Endura pushes a 14' Hobie at about 3.5 mph in still water. BS It's always the maker's claimed thrust that raises questions in my mind. They take the thrust reading stationary, as far as I know. Anyway: if you maintained 30 lb thrust at 3.4 MPH that would need 203 watts or more i.e. 17 amps at 12 volts to provide about 0.27 HP. Brian Whatcott Altus OK Yup, that's right. And the motor actually consumes about 30 amps or 360 watts. So if we believe the manufacturers specs in this case it gives an efficiency of about 56%. The 50% number appears to be about right for most trolling motors I've run across. Of course the motor is more efficient, but that number includes the prop efficiency. BS |
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