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Post Info TOPIC: Propeller Sizing


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Propeller Sizing


I just purchased a Beta 30 with a PRM 80, 2.5:1 transmission for my Caliber 33 sailboat. The engine has been installed and I am very pleased with the performance.

My propeller is 16x14, 3 blade, with a 10% clearance between the prop and the hull. At the dock with the transmission in neutral I can get 3500 rpms. Underway I can only get 2700-2800 rpms.

What do I need to do?

Thank you.

Mike Murphy 



-- Edited by Caliber on Monday 29th of June 2015 11:51:55 AM

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Guru

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Hello Mike, welcome to the forum.

You are overpropped. It is easier for the propeller to just move water (as in tied to the dock) than it is for it to actually move the boat.
My prop calc program comes up with 16"x12" three blade with 50% BAR. If your propeller has 50% blade area, I would suggest having it re-pitched.
I get the boat specifications here for my prop calc sailboatdata.com/viewrecord.asp

Have fun,
Stanley


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Veteran Member

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Posts: 52
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One good solution is to buy a Max-prop VP. You can adjust the pitch in minutes with an Allen key. I have done so several times skin diving.
This way you get the optimal pitch, as well as the advantage of a feathered prop while sailing.
Max-props are pricey, however.
PYI in Seattle sells across N America, and have as good support service for their products as Beta have for their engines.


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