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