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  #11  
Old 11-30-2009
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Great writeup "poster formerly known as Halekai"! I think that is just the information I was looking for to convince me that if I go with the fixed blade CS prop; it is the right one for the job. Still can't decide between a fixed blade and a possibly new larger Martec for ~200 more; since my prop is offset from centerline of the boat I need all the drag reduction I can get. But the CS prop looks so nice for the reasons you stated about getting the proper pitch and it being an efficient blade design.

I'm afraid that the Martec might increase my shaft vibration problem; as I don't know for sure what the cause of it is. It could be cavitation and 2-blade prop vibration; or it could be alignment or engine bed vibration (fiberglass pan). I suspect that a standard Martec could worsen it; are the Elliptec props any lower in vibration than the older Martec prop design?
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Old 12-01-2009
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TJ-

What was the recommended pitch/diameter VS the pitch/diameter combo that West by North set your prop to?

I'm thinking that I want my new prop to be slightly oversized and then just run the engine at lower RPM. 3000 RPM for a Diesel engine is very fast; and most Perkins 4-108 owners tend to run their engines in the 2200-2400 RPM range at hull speed.
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Old 12-01-2009
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Maine Sail, mind telling me what make and model your japanese genny is ?
I too have a CS prop. At 3RH 14Dx6P I can do 3300-3500rpm on my 2GM20F. I later repitch it to 14Dx7P and max I got is 2800rpm (slightly higher if prop, shaft and hull is clean). Wonder if I should go back to 6P.
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Old 12-02-2009
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How Well does the Campbell Sailor Back Down?

Maine Sail,

Your recommendation has started me thinking about the prop on Tranquility Base. How well does the Campbell Sailor on your boat back down? That's the single gripe I have with my current prop. I get maybe 10% of the acceleration in reverse that I get in forward when I increase engine speed, probably less. It makes backing into the slip on a windy day interesting.

For what it is worth, Tranquility Base has a 2 blade, fixed 13 X 10 right hand prop powered by a Yanmar 2GMF. I don't know who manufactured it, but the blade cross section is close to uniform thickness with a little curve to it. The blade width to length ratio looks very similar to the CS blades in your picture. I don't see much vibration, even at WOT. I can get to max RPM at WOT, and I ran around for 1/2 hour at WOT w/o overheating when I tested the engine last Spring. This prop drives the boat at hull speed around 2800-2900 RPM (depending on how clean the bottom is) so the pitch is good. But it won't back down worth beans. I think I could accelerate the boat faster by poling than this setup does in reverse!
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Old 05-18-2010
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Re pitching Campbell Sailor

Tractor John's post back in Nov. 2009 refers to pitching issues with Sailor prop. I'm hoping you can give me some info. regarding your setup before/after to compare. Also what was Catalina's recommendation?
I have a Catalina 36 with a M35B Universal. Michigan Wheel recommends 15" x 9" 3 blade..... Norm says" 14" x 8" 3 blade Sailor.

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Mike (MikeSB)
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Old 05-18-2010
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FWIW we went from an 18x12 Martec folder to a Campbell 17x11 without issues, smoother operation and good (much better) backing as well. The adjustment Norm is suggesting seems standard when switching to Campbell Sailor props.
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Old 09-27-2012
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Re: 3-blade fixed prop recommendations?

I sail a Marshall Sanderling (Marshall 18) catboat, equipped with a Yanmar 1GM Diesel which originally drove a generic 2-blade Michigan "Sailor" 12 x 10 prop via a 2.62:1 gear. Though the prop was properly matched (it allowed the engine to just reach its intermittent max rpm of 3600 at wide-open throttle), it produced vibration and noise out of proportion to its power. Norm at West By North Enterprises convinced me that there was no sailing advantage to the 2-blade (simple test: I stopped the prop from windmilling with my hand, and there was no change in drag when I had the prop blades vertical), and talked me into trying the Campbell Sailer 3-blade. Right off the bat I noticed far less vibration at all speeds and GALA VI was much easier to back and maneuver (though I still drop the centerboard a few inches). I also won the Catboat Class race at the 2011 Provincetown Schooner Regatta! Only problem was that the engine now topped out at just shy of 3200 rpm. After corresponding with Norm, I took the prop to a local propeller shop over the winter and had a bit of cupping removed from the trailing edge; voila-the engine now maxes out at 3500 (close enough for rhythm & blues) and I cruise the boat at about 5 kts. at 2600-2800 rpm depending on conditions. This leaves plenty of headroom for punching into strong headwinds/seas if necessary, etc. I couldn't be happier with it.
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Re: 3-blade fixed prop recommendations?

Regarding pitching issues, it seems from my own experience and what I'm seeing here that some tweaking becomes necessary when going to a CS prop; my original 2-blade was a 12" x 10" and was replaced by a 12" x 6" CS-exactly half the pitch! (I forgot to mention the dia./pitch in my previous post). As it turned out, I still had to have some adjustments made at New England Propeller in Plymouth, as the engine would not go above about 3150 rpm. They (and Norm) recommended against any further reduction in pitch, but simply removed some of the cupping. This solved the problem. While I never had any real problems backing or stopping with the old 2-blade, I notice that she's a lot more surefooted now; the only problem I have with propwalk is when I have a decent breeze pushing against my starboard side, and even then, it's more manageable. It's worth noting here that my Yanmar's Hurth/Kanzaki gear-like that on most small Yanmars-has a higher ratio astern than ahead; ahead it's 2.62:1, going astern it's 3.04:1. Even with the lower shaft speed going astern, this prop pulls its weight without overrevving the engine.

Last edited by Catboatfan; 09-27-2012 at 02:58 PM.
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Old 09-27-2012
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Re: 3-blade fixed prop recommendations?

I too have a 3 blade Campbel Sailor prop, and feel that I should report that I'm considering changing back to a larger bladed prop. I can vouch for all the advantages previously mentioned, and Norm got the size and pitch right the first time.

However, a downside I experience is that even the tiniest bit of seaweed snags on this and kills the thrust. My speed will drop from 5 knots to 2 knots when I pick up some seaweed, and it happens all the time! I've wondered if the reason I have so much trouble with seaweed is that my prop is tucked in behind the deadwood in the rudder aperture of my Alberg 30, so is handicapped from the start.

It doesn't take much seaweed either. It's rare that I can go an hour motoring without having to stop and use reverse to spin some of the seaweed off.

Previous to the CS prop, I had a large bladed Michigan Wheel style prop and it rarely had any trouble with seaweed.

-PK
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Old 09-27-2012
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Re: 3-blade fixed prop recommendations?

I'm doing a gasoline to diesel repower and am working on the same issue. I think what matters in performance is having the correct pitch/diameter/blade area combination. If you want to get into this the ultimate reference for us amatures is Gerr's "Propeller Handbook". Besides all the basic info it gives the info so you can make your own calculations. I went to Michigan Wheel and they entered thier data into thier computer and were failly close in pitch however thier blade area was too low for the cavitation curve calculations so it was good to have done them. You may find the book at the library.
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