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Old 02-18-2011, 10:00 AM   #14
markpierce
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City: Vallejo CA
Vessel Name: Carquinez Coot
Vessel Model: penultimate Seahorse Marine Coot hull #6
Join Date: Sep 2010
Posts: 12,559
RE: 3 vs. 4 blade props

Quote:
FF wrote:

Many sailboats use 2 blades with great efficiency , as they usually can carry the diameter .

I have always believed the opposite.* The typical auxiliary sailboat has a small, two-bladed propeller.* When not using the engine under sail, the two-bladed propeller can be aligned with the keel to minimize drag.* We always checked/adjusted alignment when sailing and particularly when racing.* A three-bladed propeller would have been better for motoring, but a three-bladed (non-colllapsible) propeller would create a lot of drag while sailing.

*
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