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On 11 Jan 2005 16:59:40 -0800, wrote:
I have a question that someone might be able to assist with - a
formula for - or an idea. I have a 12 inch x 10 inch 3 blade kaplan
prop for a bow thruster and I am trying to work out in rough handfuls
what power the prop will absorb at say 1500rpm.

So far I have worked out the volume of water displaced per rev/sec/min
- allowing for prop slip and the loss of area at the centre caused by
the boss and also the speed advance of the prop per rev/sec/min. This
gives a mass of water in kg moving at a velocity of metres/sec.

Somehow, I think I should be able to relate this force required to
achieve the movement into the torque and hence power required to turn
the prop, but have not yet achieved the linkage.
Wondered if anyone has any thoughts???
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If you can relate your calculations to pounds of thrust, figure about
1 hp for every 30 pounds thrust, e.g., 300 pounds of thrust is roughly
equal to 10 hp.