theoretical question.

Wee Hooker

Chief Petty Officer
Joined
Sep 11, 2005
Messages
615
Assuming the same motor, hull and prop design (basics) what is the expected difference in going to a :

1) Stainless prop of same pitch?
- Should RPM's stay teh same? Go up? down?
- Expected performance change in mid and/or top end?

2) 4 blade prop of same pitch?
-Should RPM's stay teh same? Go up? down?
- Expected performance change in mid and/or top end?


Thanks in advance.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: theoretical question.

Assuming the same motor, hull and prop design (basics) what is the expected difference in going to a :

1) Stainless prop of same pitch?
- Should RPM's stay teh same? Go up? down?
- Expected performance change in mid and/or top end?

2) 4 blade prop of same pitch?
-Should RPM's stay teh same? Go up? down?
- Expected performance change in mid and/or top end?


Thanks in advance.
It is difficult to deal in absolutes on what a prop change will do;that said.
1,changing from al. to ss will generally improve overall performance.
The degree would depend on the design of each prop.
There will likely be an rpm change how much and up or down would vary.
depending on design.
2, Generally the 4 blade can improve low -mid range performance with a slight reduction of top end speed and rpm. How much again varies depending on design. If you go to the prop store here and read the prop helps at the top and bottom of the page you'll get the idea of the various designs and their affects.
The experts can explain the finer points of prop design.
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: theoretical question.

With todays 4 blade designs it's not unusual to find that the right style 4 blade is faster than a good 3 blade prop.
 
Top