2 blade vs 3 blade prop

[Roger F]

Hi - I currently have a 2 blade prop. Just realized pitch was off and in process of having that fixed.

Question - I have read that a correctly matched 3 blade prop with result in smoother motoring, more power and better backing (less prop walk).

Not sure cost/benefit and hoping someone has some before and after experience they could share. My H306 has an 18 HP Yanmar.

cheers
roger

 

[Maine Sail]

Hi - I currently have a 2 blade prop. Just realized pitch was off and in process of having that fixed.

Question - I have read that a correctly matched 3 blade prop with result in smoother motoring, more power and better backing (less prop walk).

Not sure cost/benefit and hoping someone has some before and after experience they could share. My H306 has an 18 HP Yanmar.

cheers
roger

Roger,

Yes a three blade should be smoother, and can give more bite. Less prop walk though I think depends entirely on the prop. I have been more than satisfied with my Campbell Sailor fixed three blade. It really is an amazing and well designed fixed three blade prop that does offer less prop walk and less drag than a Michigan wheel under sail.

I switched my old C-36 from a two to a three blade wheel and the results were quite pronounced. Significantly smoother, and more available power. Speeds were also better beating into a current but in flat water were about the same.

How did you determine that you pitch was off?

If you want to get a look at a Campbell Sailor prop my boat is on the hard at Royal River. Feel free to take a peak if you are up near Yarmouth..

 

[Steve Dion]

Roger: I would have to agree with MS. I have had a couple of friends that have installed Campbell props. One of them went from a two blade to a 3 blade and it was much smoother. The other went from a 3 blade to a 3 blade Campbell.

The elimination of prop walk is normally because the prop is a smaller diameter. I believe a 3 blade prop of the same diameter will probably induce more prop walk.

The biggest advantage of a 3 blade prop is usually less vibration and better thrust against a tide or lumpy water. This is assuming that the 2 blade was sized properly. You can get a 3 bladed prop that is not properly sized and it may be worse than what you replaced.

I suggest that you contact Campbell or any other reputable shop and have them size a new prop for you.

PS: The Campbell is about $600 delivered.

 

[Ken13559]

I change my stock 2 blade to 3 blade Campbell Sailor prop and its as what MS and Steve said. With my old 2 blade, I get thumbing sound when sailing free wheel. With Campbell Sailor 3 blade, its quiet and smooth when free wheeling. The 3 blade CSP has better bite too.

 

[Paul356]

No one mentioned poorer performance when saililng with a fixed three-blade. That's the tradeoff for better motoring performance.

 

[Ken13559]

No one mentioned poorer performance when saililng with a fixed three-blade. That's the tradeoff for better motoring performance.

I didn't feel my boat sailing performance was worst off with the 3 blade CSP compared to the stock 2 blade.

 

[petersea]

There are a lot of post in the archives about this very topic. Check the archives but for what it is worth I would never have a two blade prop again after having changed to a three blade. No negatives (at least to me) and lots of positives. My only caution is to get the right size and pitch. A good prop shop can do this for you in 5 minutes.

 

[Roger F]

Thanks. Seems that the Cambell has some great reviews. MS - I noticed what seemed to be excessive vibration as well as high rpms compared with the same make boats and engines during a flotilla this year up to Mount Desert Island. Everything else has checked out fine. Had prop check by professional group in Brunswick and determined pitch was off from specs for my H306 (funny as it was stock from factory in 2004).

I am curious to Paul356 commented regarding propwalk. I have heard, all things being equal that the 3 blade would help, but logic at first glass would be that it is the same or worse.

thanks again

 

[Ken13559]

Roger, if its helps, my 3blade CSP(14Dx7P) has less prop walk than my stock 2blade (15Dx10P). I've 2GM20F.

 

[Roger F]

Difference worth the $500 plus?

Ken - I'll put that as another checkmark in the plus column, thanks. So I take it your feel the money was well spent to upgrade from looks of it. I am leaning that way and keeping the 2 blade as my backup, with pitch correction.

 

[Alan]

Paul356 raises a valid point. Sailing performance suffers with a fixed blade prop. It results in slower speed and increased weather helm particularly a 3 blade. I liken it to dragging a bucket while sailing. Both of these negatives that are unacceptable to me. For some folks sailing performance is of little or no concern but to negate it affect is like wearing blinders.
Also you may not want to blow off prop walk so quickly. It can be used to great effect while docking. I always try to dock port side and use the prop walk to great advantage almost as good as having a thruster for free.

 

[Ken13559]

Alan, your point on prop walk is correct. There're time when I wish I had alittle more prop walk.

 

[suggie]

Broken prop

Hi Guys, I have a 1995 Hunter 336 with Yanmar 27hp engine and a broken 2 blade prop. Can anyone give me the spec for this prop, or the spec for a replacement 3 blade prop. The gearbox is a 2.61 reduction unit. I am in New Zealand. I have looked everywhere for a spec, you may be my last hope! Suggie.