I believe nozzles are less efficient, but increase thrust at zero or
very low speed.
Thus, tugs use them, but nothing else.
The rest seems correct.
Likewise, optimum props would be about 3x typical diameter and 1/3
typical rise.
I am unaware of these being available, but high thrust vessels like tugs
have had similar.
This might be, theoretically, about twice as efficient as current
typical prop / transmissions..
easily verified e.g. via the motor pulling on a rope from shore vs using
a prop.
Willing to be corrected, if any empirical data is available ..
On 05/11/2016 17:30, benjatelcom@gmail.com [electricboats] wrote:
> Larger, slower turning propellers are more efficient than faster
> smaller propellers to do the same amount of work.
>
> Kort or Rice nozzle designs can help improve efficiency for slow
> moving vessels, assuming one gets an optimized propeller shape for a
> nozzle (highly swept with blade tips that contour to the diameter of
> the nozzle).
>
> Less blades improves efficiency (I can't tell if this is directed at
> sailboats only, meaning they offer reduced drag while not spinning, or
> if this is in general), but at a cost of increased vibration. Three
> blades seems to be the best balance between vibration and efficiency.
>
> Thanks in advance for dispelling any misconceptions I have. I'm new to
> boating and learning lots.
>
> Ben
--
-hanermo (cnc designs)
Posted by: Hannu Venermo <gcode.fi@gmail.com>
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