Should You Lock Your Prop Or Let It Spin

Jackdaw

Jackdaw

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Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
This of course does not speak at all to the bigger question of if locking or spinning is bad for your particular engine/transmission setup.

It does however point to the fact that if you are serious about performance, you need a folding prop.
 
B

Benny17441

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May 24, 2004
7,131
CC 30 South Florida
Did not think it was necessary to run a study to determine that a free turning prop created less drag than a locked one; it is just common sense, like pushing against a wall that yields vs. a stationary one. The real question is what is the force of the drag and its effects on boat speed. This will vary among props with those providing a larger blade surface area or shallower pitch offering more drag. The drag force will also fluctuate with boat speed. Some claim the difference between a stopped prop or a free turning one at a boat speed of over 6 knots could represent as much as a 1/2 knot loss of speed. Now that is a study I would like to see. (I apologize, I should have read the whole thing first time around) I see that the loss of speed is now calculated to be around 3/4 of a knot which is very significant, but it still does not tell me anything about the drag of my two bladed prop.
 
UM2

UM2

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Jun 11, 2014
7
Hunter 40.5 Penetanguishene
Back to the original thought, lock or spin. Let it spin. See warning in attached technical buletin.
The question should be "is it really worth installing a folding prop?"
 

Attachments

KZW

KZW

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May 17, 2014
831
Catalina 310 #307 Bluewater Bay, FL
The transmission manual on my boat says place the transmission in reverse.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
This is actually quite old news. MIT first studied this in 1994!!! The University at Strathclyde's Ocean Engineering Department studied it and I built a test rig to test this "theory" back in 2007.... Yachting Monthly I suspect took the idea for that article from the test jig I made for my testing......






KZW said:
The transmission manual on my boat says place the transmission in reverse.
Click to expand
Most 310's have a Universal engine with Hurth/ZF gear. Hurth/ZF says neutral OR reverse. Yanmar/Kanzaki's are neutral only....

 
Johnb

Johnb

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Jan 22, 2008
1,421
Hunter 37-cutter Richmond CA
The drag from a prop does not just slow you down. It affects pointing ability and therefore your ability keep sailing versus starting up the engine.

That feeling you get when the engine is shut off and you start sailing silently is ruined by the whirr of a rotating prop. I would never go back to a fixed prop.
 
A

artboas

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Jun 1, 2009
1,746
Hunter 49 toronto
Ok....

Genesis V said:
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Lock your pro
​
p, or let it spin?

To reduce drag when you’re sailing: should you lock your prop, or let it spin? Emrhys Barrell’s conclusive test settles this long-running debate, once and for all



READ ENTIRE ARTICLE
​

http://www.yachtingmonthly.com/gear/lock-prop-let-spin-29526
Click to expand
I appreciate all the work you put into this.
But the answer is to buy a 3 blade feathering prop.
Just bite the bullet. You will be a much happier (albeit slightly poorer) man
Max prop or Variprop
Do nit buy Gori
 
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