3-blade fixed prop recommendations?
I'm looking for a 3-blade fixed prop; probably want a sailboat prop but I also need something that will deliver good thrust. The sailboat props seem to have reduced blade width to minimize drag. At times we need to motor against current here on SF Bay and my current prop is just too small for my needs. The prop is a 12" x 14" on a 40hp diesel engine. I did some checking on the prop sizing tables and it looks like it is correct for the 3500 max RPM the engine will deliver; but at normal cruising RPM's of 2500 I don't get up to hull speed (7.5 kts) and I get lots of vibration above 2600 because I suspect the prop is a bit over-pitched and under-bladed which results in cavitation. My ratio is 1.5:1 (I think) which gives shaft speeds about 1/3 lower than engine RPM.
So I was wondering what others have found good results with? I am looking at the Campbell Sailer and the Michigan Wheel Sailer props; are there any others I should be looking at? How do these two compare?
Second Campbell sailor. Here's the link to their site - a lot of good information there. West by North Enterprises
I have this one and very pleased with its performance: West by North Enterprises - AutoStream Shaft Drive
Edit: Opps, not a fixed blade but worth considering IMO
On our last boat we went from a 2 blade 18x16 Martec folder to a 3 blade Campbell Sailor prop - and were surprised to have Norm (a great guy, btw) at West By North recommend a 17x11... but the prop worked great for us, much smoother under power, good "brakes" but of course a bit slower under sail.
When the time comes to reprop, if we can't spring for a folder/featherer we'll do the Campbell again... but currently leaning toward the Kiwi prop - also available from West by North.
Did you go from running at lower RPM with the 18x16 to higher RPM with the Campbell Sailer? What boat did you have and what was the engine HP and reduction? That's a huge change in prop pitch in addition to a smaller diameter.
On the Martec props; I have heard about the pins wearing the bronze at the hinges; how long does a Martec prop typically last before the prop needs repair or replacement? Seems that galvanic corrosion and wear due to thrust on those pin holes is inevitable due to the design.
On our Martec (non-geared folder) the cheeks into which the blades fit to be pinned had "splayed", opening up a bit allowing extra clearance for some vibration. While we coveted a MAX prop, just couldn't justify the cost for the type of sailing we did then. The Campbell was a good (inexpensive ~$750CDN 10 years ago) compromise.
Re: Campbell Sailor
Here's a review I posted on another forum earlier this fall:
After much research and consternation I decided on a new prop this past winter.
Mechanical vs. Fixed:
As much as I would have liked a feathering prop, Max-Prop was my choice, I decided against it after speaking at length with my local prop shop and a few friends at boat yards. With the tides in Maine we get lots of floating debris, floating line and lobster pots. As was stated to me by more than one prop shop, and more than one boat yard employee, the mechanical props are just not as reliable when you hit something. This happens in Maine. This is not to say they are not durable but when I was staring at a four year old mechanical prop overhaul, on the bench at my local shop, for "$900.00-$1000.00", it made my decision that much easier.
The minimal drag of a feathering prop would be awesome but I don't race my own boat so 3-6 seconds per mile lost out to durability, simplicity and reliability. Folders were not even considered this time around and because I have already owned them in the past it was easy to rule them out this time.
Two blades vs. three:
For me this one is easy. Over the years I have had numerous two blade props and have never found one I liked. When I want to use my motor I want a real motor not the feel of an electric trolling motor.;) With the tidal currents in Maine and the lack of summer winds we often see, having a smooth well balanced three blade prop is a must for us.
I am not one who is afraid to fire up the Japanese genny when the wind dips below 5 knots, especially with an antsy toddler who's ready for some island exploring etc... We also like to venture up some of our many rivers which can have massive currents. Two blade props have never given me a feeling of total confidence, with a small aux motor, in battling head on with these currents.
Which Fixed Prop?:
After lots of research I decided on a Campbell Sailor Prop ("CS" from here forth). I had read many, many, many prop reviews & discussions using the search tool on about 20+ sailing forums, from SBO to SCCA to SailNet, and every one in-between. One thing I noticed was that I had not read much if any negative comments about the CS. So the Campbell Sailor three blade it was.
After consulting with Norm at West By North, the makers of the Campbell Sailor. I ordered a 16"X10X1" RH prop. The prop took about three to four weeks for delivery which was fine due to my off season planning.
Contrary to popular beliefs and misconceptions prop sizing is NOT an exact science. In order to hit max RPM and size the prop to do that without going over or under by much is not easy and often takes two or more attempts to get it spot on. I can remember working with my old friend Brian, a marine surveyor, who always checked the prop sizing against max rated RPM. We found that close to half the boats had the wrong size prop.
The CS prop is EXTREMELY efficient. Norm spec'd mine at 16" diameter X a 10 pitch. I was skeptical at first because my three blade Michigan Wheel was a 16" X 12 pitch which is a lot more aggressive. I could not understand how, with loosing so much surface area, I could also reduce pitch? Norm used the Michigan Wheel prop size calculator, which he tweaks for the CS prop design, and decided on the 16X10. Unfortunately when I got the 16X10 it was still over propped and I was under max rated RPM by about 300 RPM. Not good.. Over propping your engine is never a good idea so I wanted to fix this as soon as possible.
Once I discovered the 16X10 was still to aggressive, despite the blade surface area being MUCH smaller than the Michigan Wheel, I called Norm. Norm decided to drop the pitch to a 9 and remove some of the cupping on the trailing edge of the CS props blade.
The customer service Norm provides is stellar! He actually sent me a brand new replacement prop ahead of time so I could literally change out my prop, with the boat still in the slings, and then send the used 16X10 prop back. The 16X9 prop worked flawlessly and I am now within 30 RPM of max rated with a clean bottom and prop.
If you've been paying attention the Campbell Sailor is a full 3 increments of pitch smaller than the Michigan Wheel prop and has far less surface area for less drag through the water. Efficient does not even begin to describe this props unique design. Pitch is basically the theoretical travel a prop makes in one revolution. For example a 10 pitch will theoretically travel 10" in one full revolution provided there is no "slip", but there is almost always slip..
Vibration / Smoothness:
This prop has proven to be the smoothest prop I have ever used or owned on a sailboat. The drive train exhibits no vibration throughout the entire RPM range even at WOT. My Michigan Wheel was tuned and balanced less than one year ago and still could not compete with the smoothness of the CS even on a brand new shaft.
Despite the aggressive design of the CS blades the prop displays considerably less prop walk than did the Michigan Wheel. I can not say it has none, but it is about 70% better than the fixed three blade Michigan was.
As some of you may know I conducted my own little prop drag study. The results were rather eye opening. The CS prop has about 13 pounds real of drag at about 4.2-4.4 knots while the three blade Michigan Wheel had about 39 pounds of drag at only 4-4.2 knots. For those of you doing the math that is roughly a 200% increase of drag for the Michigan 16X12 than for the CS 16X10. Yes, this is still more drag than a Max-Prop but nowhere near the drag of the Michigan Wheel..
I have always run my boat to put the stern wave right at point where my the hull sides and transom meet but without the water climbing up the transom. This puts me at about 6.6-6.8 knots. I used to be at 2400 RPM to do this with the 16X12 Michigan Wheel and am now consistently at about 2250 to do the exact same thing with the CS 16X9. Both props would hit a WOT max rated throttle of 3000 RPM within +/- 30 RPM.
I could not decipher any real measurable difference in fuel consumption perhaps because we also have engine driven refrigeration which tends wreck the mathematics of measuring fuel consumption for moving the vessel through the water.
If you are looking for a rugged, reliable, smooth and efficient fixed three blade prop with less drag than the typical Michigan Wheels, that come standard on most boats, then the Campbell Sailor certainly fits the bill.
While slightly more expensive than a Michigan Wheel it is certainly considerably less than any of the feathering or folders. I think i paid about $540.00 delivered but I'll need to find my credit card statement to be sure..
I waited until I had nearly a full season of use to post this so it could be more accurate and less impulsive. I find if I write something shortly after I buy it I can be admittedly little more biased, in a pro fashion, towards it, then if I wait and use it more. After nearly a full season of use I find I like it even more now than when I initially bought it, perhaps due to the sizing mishap.
Here's cross sectional comparison of the props unique design comparing the CS to the MW:
Here's a photo of the sheer reduction in surface are which helps result in the 200% reduction in drag between the MW and the CS (13 pounds vs. 39 pounds):
Having purchased a Campbell sailer myself I second everything that has been said and will buy another when I need to. But I was not told that I would be charged for repitching and ultimately paid several hundred more to get it right.
Now if they had used my requested pitch (based on Catalina factory recomend) rather than their own ideas initially I would expect it to pay for changes, but they (CS) told me they new best from experience. The final pitch was exactly what I had asked for originally (Catalina did know best)
So I would get it in writing who is paying for repitching and the associated costs. Two repitch's meant pulling the boat three times. Ouch. thanks Norm
|All times are GMT -4. The time now is 08:39 PM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012