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TWO OR THREE BLADE PROP

Aug 11, 2011
549
O'day 30 Feeling Nauti GEORGETOWN, MD
What differences will I experience? Speed, handling, Fuel consumption, lower revolutions? What do folks think. As always your responses are appreciated.
 
Oct 22, 2014
11,729
CAL 35 Cruiser Portland OR, moored EVERETT WA
What do you have now? What do you hope to change with a new prop?
 
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SG

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Feb 11, 2017
1,656
J/Boat J/160 Annapolis
Three bladed has significantly more drag while sailing; and, MIGHT offer more power in forward or reverse -- depending on whether it's properly matched to engine.

As John asks above: What do you have currently? What's the issue?

Beyond that: What's your general pattern of sailing? e.g., How much do you sail vs. motoring?
 
Aug 11, 2011
549
O'day 30 Feeling Nauti GEORGETOWN, MD
Currently I have a two blade. I have an opportunity to obtain a folding three blade. I ask the questions, in order to make an informed decision as to whether or not to invest. If the difference is minimum, I see no reason to spend. However if it makes maneuvering the boat in either direction easier, save on fuel, lower rpm's, then maybe its worth it.
I'm a casual sailor, not a racer, just enjoy the speed obtainable, pending winds and currents.
 
Jul 7, 2004
6,379
Hunter 30T Cheney, KS
The ability to fold cancels the drag problem. The size and pitch is the important motoring question. Is it a good price? It mY not be worth $$$ to a casual sailor.
 

Johnb

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Jan 22, 2008
1,140
Hunter 37-cutter Richmond CA
If you have a fixed prop and have the opportunity to get a folding/feathering feathering one I would go for it. Changing just because 3 is more than 2 is not worth it.
 
Oct 22, 2014
11,729
CAL 35 Cruiser Portland OR, moored EVERETT WA
Thank you that helps put context to your question.

A 3 blade may provide more power at a set rpm, but not necessarily at a grand savings. Some feel it smooths out the propulsion. With a well designed folder you should get this power with out impacting your sailing.

Note design and power settings are based on running your Diesel engine at optimal efficiency rpm. Running it slower will make the engine less efficient.

Economics of a prop is more a personal decision.
Good luck.
 

SG

.
Feb 11, 2017
1,656
J/Boat J/160 Annapolis
Do you mean a 3-blade FOLDING or a 3-blade FEATHERING? Which prop? Some are adjustable pitch (not variable, just adjustable).

I think a folding prop, for a casual sailor who doesn't have his prop and bottom wiped down every couple or so weeks in the summer in Georgetown, MD might have some issues with "gunk" build-up. A 2-blade Max Prop wouldn't probably be an issue; I'm not sure about the 3-bladed models, in terms of more "bullet-proof".

There might be 1/2 knot or more difference in sailing performance over a 2-bladed prop --- even more for a 3-bladed one. On an O'Day 30, that's a bigger percentage difference than you might think.
 
May 17, 2004
2,276
Beneteau Oceanis 37 LE Havre de Grace
I’m very happy having switched from a fixed prop to folding, but both were 3 bladed, so not quite the same situation. Ours is a 3 blades Flex O Fold. Sailing performance is much better especially on low wind days. Motoring performance is about the same, certainly no worse than the 3 blade fixed was. Never had any problems with it fouling or failing to fold/unfold.

From your description it sounds to me like there’s a specific 3 bladed prop that might be available to you? If that’s the case I would make the decision largely based on whether the 3 blade is the right diameter and pitch for your boat. Switching to something that’s not the appropriate size could do more harm than good ifit leaves you over propped and your engine bogging.
 
May 24, 2004
6,120
CC 30 South Florida
assuming your current prop is properly sized you will not experience any increase in speed; you will experience a reduction in prop walk with better handling in close quarters and perhaps smoother acceleration. Under sail the 3 blade prop will suffer a significant increase in drag over its 2 blade counterpart. The loss of speed due to enhanced drag could approach 1/2 knot. If both props are properly sized you should not experience any change in fuel consumption. Is the loss of sailing speed worth the better and smoother handling in close quarters? Your call.
 
May 17, 2004
2,276
Beneteau Oceanis 37 LE Havre de Grace
assuming your current prop is properly sized you will not experience any increase in speed; you will experience a reduction in prop walk with better handling in close quarters and perhaps smoother acceleration. Under sail the 3 blade prop will suffer a significant increase in drag over its 2 blade counterpart. The loss of speed due to enhanced drag could approach 1/2 knot. If both props are properly sized you should not experience any change in fuel consumption. Is the loss of sailing speed worth the better and smoother handling in close quarters? Your call.
A little further down the thread he pointed out the 3 blade would be a folder, so it would be an improvement in sailing speed, not a loss.
 
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Jun 4, 2004
911
Hunter 410 Punta Gorda
Just sure the prop you are looking at is the right size for your boat/engine. You should check with flex o fold to make sure.
 
Jun 1, 2007
213
O'Day 322 Mt.Sinai
On my O'Day 322, I love my new Campbell Sailor 3 blade fixed prop. Great power when needed, boat sails well with the engine shut down. I replaced my feathering prop with the fixed and will never look back. I don't race, just cruise and day sail. love it!
 
Jul 27, 2011
3,590
Bavaria 38E Alamitos Bay
Not a fan here of “opportunistic upgrades”, i.e., ones that have not been on the docket or otherwise under evaluation. It’s like the old “buy now and save” selling pitch. It sounds as if you have not considered converting to a folding or feathering 3-blade prop prior to this “opportunity.” When/if you discover you actually do need one, you can likely find one for the price of a bottom job, etc.

Frankly, IMHO, unless you’re racing in light airs frequently or planning a couple-thousand-mile sailing voyage, under sail nearly all of the way, you do not need one. If you wish to reduce drag more, mark the shaft to align the two-blade vertically behind the strut.
 
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May 17, 2004
2,276
Beneteau Oceanis 37 LE Havre de Grace
If you wish to reduce drag more, mark the shaft to align the two-blade vertically behind the strut (or skeg).
The strut on an O’Day 30 is about 1/4” thick; way less than the prop itself. I don’t think there’s much to be gained trying to hide the prop behind it. Certainly not as much as with a skeg.
 
Jul 27, 2011
3,590
Bavaria 38E Alamitos Bay
The strut on an O’Day 30 is about 1/4” thick; way less than the prop itself. I don’t think there’s much to be gained trying to hide the prop behind it. Certainly not as much as with a skeg.
It’s a slight improvement over leaving the blades a-thwarts, people contend. And yes, I know only the top blade gets any protection at all. I did this routinely when racing my Pearson 30. However, come to think of it now, I believe the prop would be fwd of a skeg. (I’ve corrected above.)
 
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Aug 11, 2011
549
O'day 30 Feeling Nauti GEORGETOWN, MD
Then I take the wisdom of the group and for go this opportunity. Thanks for all your input. I've learnt a lot from this one thread. Happy New year to all.
 
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May 20, 2016
2,890
Catalina 36 MK1 94 Everett, WA
It all depends on make and model of the folder. I’ve operated boats with some folders that are horrible in reverse. Check out the Yachting Word (IIRC) article on performance of various folders/feathering/fixed props before you jump.