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Old 20-08-2015, 11:45   #16
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Re: New Prop

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Originally Posted by Cheechako View Post
It depends. The old Gori folding used on many racing boats were terrible and did not push the boat thru chop or work in reverse hardly at all.
A feathering Max Prop does both better than a fixed blade. The devil is in the details. You theory may be right but your reality isn't! just sayin....
No,
Jim is correct, a Max Prop's blade design is NOT as efficient as any decent fixed prop, as far as providing propulsion. It is more efficient when sailing of course.
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Old 20-08-2015, 12:00   #17
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Re: New Prop

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Originally Posted by Twill View Post
I will be hauling out in the fall to do some other bottom work anyway> Can I get a consensus...Will a three blade make me faster ?? if not I will save myself the trouble and stay with the old prop. My boat is 9800 pounds a 4'11' fin and spade rudder. The prop shaft is old school one support strut. I have a slight vibration at moderate RPM very little at idle and very little at full power. My engine is a Yanmar 2 cylinder 16 hp. Thanks
NO. As I said early on, a 2 blade or 3 blade will get you to hull speed if you are propped correctly. A 3 blade may stop you quicker in reverse and may punch thru waves better though.
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Old 20-08-2015, 15:04   #18
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Re: New Prop

Twill, the bitter truth MAY be that you are being limited by lack of horsepower rather than your prop. 16 rated HP isn't all that much for a 9800 lb vessel, and if your bttom is a bit foul or there are a couple of barnies on the prop... it just might not be enough.

And I don't think you have mentioned whether you can reach full rated RPM with your current setup... that bit of data would help us analyze your situation.

And for Cheech, I can't agree with you, nor can MIT and many other maritime experts.

Jim
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Old 20-08-2015, 17:51   #19
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Re: New Prop

Going from memory regarding testing, the Max is between 98/99% in terms of speed as a fixed 3 blade and of course was the best tested including folding, feathering and fixed at stopping the boat in reverse.
To me that’s efficient for everyday use especially if you then include low sailing drag..If I remember right the props tested were on a smaller boat also, the large hub of the Max is less efficient in smaller sizes, It should only get better in the size boats many have.
Of course “efficient” can mean a lot of things in different context, so we have to specify “efficient at what” I guess., A Max Prop is definitely not cost efficient when it comes to purchase price!
A hydroplane prop may be very "efficient". But at what? How would that work out on a 46 ft displacement hull? As I said earlier, the devil is in the detail.
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