Prop Efficiency in Reverse

[phillip]

Manoeuvring a 24' sloop under auxiliary power with through hub exhaust. Would changing the number of blades improve the prop. efficiency when climbing through the exhaust in reverse?
I read the thread discussing reventing of exhaust by racers and wonder if there is an application here or would a simple prop change do the job.

Thanks
Phil

[cyclops]

I am going to apply logic to this one. A 1/2 blade prop has the greatest diameter. A 5 blade prop 25% approx. smaller dia.. Therefore the more blades the greater the chance of exhaust bubbles disturbing the prop flow and causing some loss of eff. How much in either diriction is up to a empirical testing of bollard pull, speed and turn diameter. My best shot.

[phillip]

So are you thinking 2 blade>larger diameter> match the pitch on the 3 blade. The 2 blade same rpm might pull more useable water out of the thrust zone?(If that's what you call it?)

Thanks Phil

[cyclops]

In theory, yes. In practice, lower the motor or get a bigger one to better control the boat.