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post #6 of Old 11-10-2004
ASA and PSIA Instructor
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2 blade or 3 blade propeller

I still don''t get what the coversation of 2 versus 3 is supposed to be about...

My understanding is that thrust is a factor of blade area, and the proper blade area is determined by engine HP and boat displacement. You can get your blade area two ways - a larger prop with only two blades, or a smaller prop with three blades, but both with the same blade area, or your engine will not run at cruising RPM. Regardless, the performance or the props will be basically the only NEED a three blade when the proper sized two blade would not have adequate clearance around it. If you buy a three blade when a two blade would fit, you have simply wasted some money to no benefit...
Which is a common enuff syndrome in sailing...
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