Propeller Advice - 3 or 4 blade and what pitch?

[Toronto boater]

I have a 19.5 foot Sunbird Corsair Cuddy with an OMC 4.3L Cobra I/O engine.
With two passengers, and mimimal load, I get the following stats from the 17" pitch, aluminum Solas, 3 blade propeller:

wide open throttle (trimmed up): 4500 RPMs at 41 mph
3000 RPMs (trimmed down): 26 mph
coming off plane at about 21-22 mph

With a couple more passengers on board it is really slow out of the hole and doesn't hold plane well at lower speeds. I want to increase the performance to get better hole shot and handling at lower speeds. I am willing to sacrifice a couple of mph at the top end. I am an avid slalom waterskiier.

Any suggestions as to whether a 3 or 4 blade propeller is best?
If so, at what pitch?
Any suggestions as to make/model?
Note that I tried a 21 inch 3 blade pitch propeller and the hole shot was just awful so I switched to the 17 inch.

Any thoughts would be appreciated.
Thanks.

 

[steelespike]

Re: Propeller Advice - 3 or 4 blade and what pitch?

A 4 blade should improve low end performance. I believe you should drop an inch in pitch.Top end will probably be lower.Try to stick with same brand and material.Another thought is trim tabs of some sort.Smart tabs are reasonable less complicated and have good factory support.They will improve hole shot, handling and ride,resist no wake speed wander and stay on plane at lower power.The experts may be along with more specific prop recomendations.

 

[Don Dickinson]

Re: Propeller Advice - 3 or 4 blade and what pitch?

one thing you can do is install trim tabs ... www.nauticusinc.com .. they will let you plane at a lower speed and improve time-to-plane. lowering the pitch will help with the hole shot. changing to 4 blade will probably do the same thing. stainless steel instead of aluminum will help maintain your top end at the lower pitch. i'm not a pro on props, but those are some things to think about.

best regards,
don