Prop Walk

M

Mark Arnold

.
Apr 2, 2018
2
Hunter 33.5 Grand Rivers Kentucky
Hi All!
I just purchased a 2007 Beneteau 343 with a standard two blade prop. I have already noticed quite a bit of prop walk to port while in stern propulsion. Pretty extreme... Has anyone had experience with updating to a three blade prop - and if so - has it decreased the prop walk when in reverse???
Thanks
Mark
 
Gunni

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
You will still have the prop walk, and a prop that has only marginally more thrust. That is why many change over to a Max Prop for the greatly increased reverse thrust which helps your rudder move you right.
 
M

Mark Arnold

.
Apr 2, 2018
2
Hunter 33.5 Grand Rivers Kentucky
Gunni said:
You will still have the prop walk, and a prop that has only marginally more thrust. That is why many change over to a Max Prop for the greatly increased reverse thrust which helps your rudder move you right.
Click to expand
Thanks - good info
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
@Mark Arnold Another option is to look at a “Campbell Sailor” prop. I just installed one and after a 4 day 120 NM cruise am very pleased.
The original prop was a Michigan blade.
08D93E42-71D5-4623-8BD6-D292C229CEA5.jpeg
And now I have this.
017E05C1-2358-449D-98FC-07ECB47DDB8A.jpeg
The difference has been significant. I am getting about 1 knot better thrust at 500 RPMs less going forward. There is marginal prop walk in forward and almost none in reverse. I need to really work now to spin the boat in it’s own length. Before it was automatic, put it in gear at idle and spin. I got maybe a knot better sailing speed with no cavitation doing hull speed. Before cavitation was very evident when the boat was nearing hull speed down a wave. For about $1200 I think it was a very good spending of boat bucks.
 
NYSail

NYSail

.
Jan 6, 2006
3,145
Beneteau 423 Mt. Sinai, NY
jssailem said:
@Mark Arnold Another option is to look at a “Campbell Sailor” prop. I just installed one and after a 4 day 120 NM cruise am very pleased.
The original prop was a Michigan blade.
View attachment 149909
And now I have this.
View attachment 149911
The difference has been significant. I am getting about 1 knot better thrust at 500 RPMs less going forward. There is marginal prop walk in forward and almost none in reverse. I need to really work now to spin the boat in it’s own length. Before it was automatic, put it in gear at idle and spin. I got maybe a knot better sailing speed with no cavitation doing hull speed. Before cavitation was very evident when the boat was nearing hull speed down a wave. For about $1200 I think it was a very good spending of boat bucks.
Click to expand
Nice prop!
 
T

ToddS

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Sep 11, 2017
248
Beneteau 373 Cape Cod
yes... BUT... I went from a 2 blade fixed prop to a 3 blade feathering (Gori) prop on a new (new to me) boat. The prop walk is WAY WAY better with the 3-blade prop, but it is not at all a fair comparison, since it is a different prop, but also a different keel, engine, transmission, rudder, etc. I'm sure the prop is a major factor in the improvement, but too many variables for me to make a convincing argument for you.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
ToddS said:
The prop walk is WAY WAY better with the 3-blade prop
Click to expand
What do you mean by "Way Way better"? Less prop walk from the folding prop or more?
Both your Beneteau and the Hunter are fin like keels. This gets the prop out in the water and less shield by the keel. So the effects of the prop in the water will be similar.
The 2 blade was thought to be better for sailing especially when the operator could hide the prop out of the water stream behind the keel. You had to rotate the shaft to a mark that corresponded with the prop being in a vertical position then lock the shaft in gear to keep it there. n my boat set up that would work as the prop is near to a fairly massive keel. (44 year old design). This idea has nearly no effect on your new modern hull designs. Thus the engineering of a folding prop.

So Todd the question is about powering the boat not sailing. Under power with the Gori prop do you feel the boat tracks a straight course when you shift into reverse? Is this more or less then you remember when the 2 blade fixed prop was attached?
 
T

ToddS

.
Sep 11, 2017
248
Beneteau 373 Cape Cod
My new boat (Beneteau 373) has the fin/bulb keel you describe, and has the 3-blade feathering Gori prop. It backs up fairly straight, with only a little walk to the side (in the VERY limited time I've spent on her). My old boat was a 1964 Allied Seabreeze... so... full keel where the prop essentially emerged directly from the aft end of the keel, with the 2 blade fixed prop... which seemed to pull sideways as much as aft (I have no scientific measurements of any of that... just how it "feels" in my 20 years of experience on the old boat, and a few days on the new boat). As I stated, there are many variables beyond the prop itself... the shape and position of the rudder, and hull, the length of the waterline, etc. etc... That's why I answered "yes... but... it is not at all a fair comparison".
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
Thanks. That helps. It is a relevant comparison. It always is more subjective than scientific when we’re stating our experience.
There are attempts at scientific comparison by prop folk but they are often in a vacuum without the boat shape, size, form, etc elements.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
Yes it can @Doug4bass then again if you don’t understand it you can get in a lot of trouble.
 
S

SFS

.
Aug 18, 2015
2,088
Currently Boatless Okinawa
@jssailem - John, what size prop did you buy from CS? I'm wondering if they have gone WAY up or if you just have a bigger prop than I would use. Two years ago they quoted me about $585 for a 3-blade 14x8 RH for a 1" shaft. I don't want to miss a chance to kick myself for not pulling the trigger then. I also think the exhange rate would work in my favor, given that CS is a Canadian company.

Edit: Found the quote and corrected the amount above. Shipping to me in FL would have been another $48.
 
B

Benny17441

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May 24, 2004
7,174
CC 30 South Florida
Look also at the downside, a three blade prop will also add significant drag when the boat is under sail. A folding prop may be the answer but their workings bring a lot of other factors.
 
DougM

DougM

.
Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
Went to a 2 blade Gori from the original fixed 2 blade Michigan Wheel prop because Yanmar stated not to lock the prop shaft when sailing, but to let it freewheel. That drove me crazy because of the constant rolling sound. I actually felt that prop walk was reduced with the Gori (either that or I learned how to anticipate and compensate for it). I gained almost a knot in sailing speed as well.
The original Gori I had was slightly over pitched and I could not reach max engine rpm so I just bought a new one with an inch less pitch. We will see if that impacts prop walk.
Subsequently I have a perfectly good 16 x 3-1/2 gori sitting on the shelf gathering dust.
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
@SFS the CS prop is 22” RH 13p. It replaces a 24” RH 14p prop. It is much bigger and then yours. I had several conversations with Kelsey in BC. He is very knowledgeable and careful to find the best configuration for boat and motor.
I can now hit boat speed 7.2 at 2800rpm. 200 shy of WOT. I found a comfortable engine noise vibration limited cruising at 2500-2600 rpm. Still need to get fuel consumption numbers but the 85nm run I did under power last week was very easy.
 
S

SFS

.
Aug 18, 2015
2,088
Currently Boatless Okinawa
Yes, that's more than 50% larger than mine. Thanks for the clarification. Any thoughts or data on drag while sailing?
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
I had the boat out last week. Got to sail across the Juan D'Fuca strait (about 30 nm) on a broad reach. Wind built from 3 to 17 Knots over the 5 hours. I was very pleased. No cavitation was experienced. Average cruising speed was recorded at 6.2 knots. I made this same run with similar conditions last October using the old prop and there was prop cavitation that set up odd vibrations. I think I have improved my sailing performance by 30%, maybe a bit more. Certainly as a cruiser not a racer that is a big step.
 
Davidasailor26

Davidasailor26

.
May 17, 2004
5,704
Beneteau Oceanis 37 Havre de Grace
SFS said:
Yes, that's more than 50% larger than mine. Thanks for the clarification. Any thoughts or data on drag while sailing?
Click to expand
Here's a comparison of my close hauled boat speed from races over the last few seasons. Orange dots are the OEM fixed prop, blue are 3 blade FlexOFold. Solid lines are best fit trends. Basically at low wind speed the FOF is about a knot faster. Close to hull speed the speeds match. At high winds speeds the fixed prop made lots of turbulence in front of the rudder so it took a lot of rudder angle to overcome weather helm, slowing the boat again.

Screenshot_20180509-201214.png

Caveat - The FOF was the last season, so some of the speed improvement may come from having learned the boat better.
 
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jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,264
CAL 35 Cruiser #21 moored EVERETT WA
@Davidasailor26 The record shows significant speed improvement. Bet you love the FOF.
 
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