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Feathering Prop vs. Fixed Blade Prop

22K views 70 replies 28 participants last post by  Maine Sail 
#1 ·
I have a 2000 Pacific Seacraft 40, with a 3 blade Max-Pro feathering prop (18" diameter, 13" pitch) which unfortunately needs to be replaced. I am leaning towards a fixed 3 blade prop. Specifically a Campbell Sailer, (17" diameter, 9" pitch), manufactured by West by North Enterprises. The manufacture recommended the smaller diameter and pitch. Apparently this has been the case for other customers too; the claim is this prop design is more efficient and therefore can be smaller. This appears to be largely substantiated by others who have purchased this prop.

Therefore my questions are more about how much of a difference in performance I might notice moving to a fixed prop. Specifically:

1. Will I have significantly less control in reverse
2. Is there appreciable increase in drag under sail
3. Comments on this brand

Thanks!
 
#3 ·
I believe Nigel Calder wrote a rather lengthy section on the prop selection for his PSC 40 in his book, but I don't have a copy with me, so I can't cite it. However, my recollection is that he discusses fixed prop diameter and pitch for the 40 quite thoroughly. I'd recommend it as a good resource.

Based on my experience, the MaxProp does provide very nice control in reverse on the 40. I've had a MaxProp on the boat the entire time I've owned it, so I can't comment on side-by-side comparison with a fixed. Based on other boats I've had and sailed, however, I'd say you'll always have better control with the folder -- and much less "prop-walk" when you back. However, it is sure to reduce your speed under sail. How much, I can't say for sure, but I'd guess that Sailingfool's .5 knot estimate is a fiar one. That said, though, you may get more speed when powering forward underway with a fixed prop.
So, if you're planning a long inland trip, for example, the ICW on the East Coast where you'll be doing a lot of motoring, a fixed three-blade may be something to consider. Some years ago, I met one sailor boat who put a fixed three-blade on his boat when he left the Chesapeake going south and then had the boat hauled and put a folding prop back on when he got south and was ready to head for the islands.

Then again, if you're voyaging to somewhere quite remote, the great thing about a fixed prop is no moving parts. Much less to worry about. If a MaxProp somehow gets toasted in a remote Pacific archipelago, repair or replacement may be challenging indeed.

All the foregoing, I guess, suggests one way to approach the the prop decision is to consider how and where the boat will be used.

Roger Lopata
JUNO
PSC 40 - #46
 
#5 ·
Darold,
I have a Campbell Sailor Prop on my C37.I have not had a Max Prop so cannot make a comparison but I can give some comment on the Sailor prop.I have very good forward thrust and serious prop walk in reverse.My prop was delivered with the wrong pitch and had to be repitched by Campbell ( only Campbell will do the repitch)a real hassle.When sailing the drag is negligible, I sail right along with other boats and pass many.
If you are into racing the feathering prop is obviously the way to go but if you are cruising I think the simpler non mechanical prop is best.
One last note ,when I repowered and reproped the engine supplier warned me that he had had numerous problems with incorrect pitch on Sailor props and recommended Michigan props.I ignored that advice and did get a incorrectly pitched prop.
 
#8 ·
When sailing the drag is negligible, I sail right along with other boats and pass many.
I would argue that the drag when using any fixed-blade prop is not "negligible". While it may be true that you keep up with, or pass, other boats, this is an "apples and oranges" comparison, and of little real value when discussing the performance of the prop. But if you can keep up with the competition now, think how you'd blow their doors off with a feathering prop! ;)
 
#6 · (Edited)
Replace a MaxProp with a fixed prop? Oh the humanity !! :)

Regarding question 1: Yes, no question the MaxProp is better for moving the boat in reverse than a fixed prop (less prop walk, better acceleration from a standing start).
Regarding question 2: The additional drag may not be a big deal for local short sails, but it'll add up to be significant for long distance sailing. Other previous threads here at Sailnet have discussed this point, so you may want to search for them.
Regarding question 3: I'm not familiar with the Campbell, but I'd be suspicious of a vendor's claim of greater efficiency as the science of prop design is well established. It's important to match the prop's performance with your engine to ensure it can reach its specified maximum RPM (else you risk shortening the life of your engine).

If there's a chance of refurbishing the MaxProp, possibly by sending it to PYI even (call them and ask them about it - it may be less expensive than you think), I'd consider doing that. If that wasn't feasible, I'd look at another MaxProp or perhaps an AutoProp.
 
#7 ·
One other thought regarding prop efficiency (stating the obvious, but since the salesperson brought it up . . .)

Fixed props are more efficient than feathering props for propelling the boat forward while motoring. If one has a power boat, he'll want the most efficient prop for providing forward motion under power.

For sailing vessels, efficiency has to be measured both under sail (weighted heavily since it's a high percentage of our usage) and under power. At least for racing or long distance sailing, the drag question becomes an important factor when considering overall efficiency, yes?
 
#9 ·
A Quick Follow-up Regarding Calder's Calculations

I dug out my copy of Calder's Cruising Handbook, and he has more than five pages of text and formulas he used when deciding on the prop for his PSC 40, NADA.

Bottom line: Calder went with a three-bladed fixed 18-inch prop with a 12-inch pitch. He claimed it provided 7 knots at 3,000 rpm and topped out at 8 knots (He must have really been running that Yanmar hard to do that).

Roger Lopata
JUNO
PSC 40 -- #46
 
#10 ·
A Quick Follow-up Regarding Calder's Calculations

Bottom line: Calder went with a three-bladed fixed 18-inch prop with a 12-inch pitch. He claimed it provided 7 knots at 3,000 rpm and topped out at 8 knots (He must have really been running that Yanmar hard to do that).
I have all Nigel's books and have read them through, but they're not handy at the moment. The information you're citing regards efficiency of the prop under power, but I'm pretty sure he assessed the drag issue as well. If you have it handy, can you remind us / summarize his feelings concerning drag?

Regardless of the efficiency issues, for me the (near) lack of prop walk in reverse is nice as I single hand a lot and it's one less thing to have to manage. I guess as with everything else sailing, it comes down to one's requirements, priorities, and preferences.
 
#18 ·
My biggest concern with non-fixed prop, is that it will decide to stop
feathering, requires more maintenance, and will require a haul-out if it
does fail.
As I have stated many times in this forum, no prop, fixed, folding or feathering requires a haulout for repair or maintenance. A qualified diver can pull and reinstall any prop made while the boat is in the water, Max Prop included.
 
#12 ·
Calder on drag (MC1's Question)

Calder doesn't offer any specific formulas or numbers but says most folding and feathering props will "greatly reduce drag when under sail, so it is ironic to see their proliferation at a time when less and less time is spent under sail" (page 201).

He goes on to rank two-bladed folders as best for sailing (least drag) and worst under power; feathering props, like MaxProp, as having a bit more drag and as being almost comparable to fixed props in forward and better in reverse; and variable pitch props, like Brunstons, as having more drag than feathering but "significantly improved performance under power throughout a boat's speed range" (202).

And, to give credit where credit is due, the citations above are from Nigel Calder's Cruising Handbook, International Marine/McGraw Hill, Camden, ME, 2001.

I couldn't find anything much more specific about drag in that section of the book, but Calder's comments on the sailing side of the issue would seem to have face validity. If one looks at the underwater profiles of the props, it would seem logical as to which would create the most drag under sail.

Roger Lopata
JUNO
PSC 40 -- #46
 
#14 ·
Thanks for the insight.

Thanks everyone for your advice. This has been very useful.

We are planning for extensive cruising to far away lands. So performance under sail for long legs is important. I also single hand a lot and have a tight slip, so prop walk is a concern. And occasionally I am motoring in SF Bay and the Delta, contenting with strong currents.

So in summary it appears as follows:
  • Forward thrust - performance is about the same (slight advantage with fixed)
  • Reverse thrust - less prop walk and better acceleration with feathering prop
  • Under sail - feathering prop leads (with some mixed opinions)
So I guess the biggest trade off for me is: better control in reverse or a lower maintenance prop. I'm always for simplifying a system when possible if it can be achieved without sacrificing performance or safety. So I'll get a fixed-prop, but also look into getting my Max prop fixed (great idea - only the blades are in poor condition, the hub and gears are very clean). And then take this question to sea for an experiment.

If I can live with the performance of the fixed prop, and have lower maintenance to boot, I'll go that route. If not I'll replace with the refurbished Max prop. In either case I'll have a back up prop while cruising around the world.

And I'll add Nigel Calder's Cruising Handbook to my library. Great summary, Roger, Thanks!

Thanks again for sharing your thoughts and experience.
 
#15 ·
Max Prop vs. Feathering

Everyone has an opinion on this one.

My boatyard is really anti-Max Prop. I was seriously considering going with a fixed prop as two of my buddies were. I was going this way largely because of the every 3 month zinc change and the purported better motoring. I have decided to hold off for a bit longer given the experiences of my two friends.

The first has a Tartan 40 and a Westerbeke 40+. He had the prescribed new 3 blade prop installed and he is miserable. His speed has decreased at the same rpm and his backing down is worse. He may have been stressing his engine with the Max Prop's settings he was using but he is really unhappy.

The second friend has a Moody 42 with the same engine as me, Yanmar 4jh2te. He put on the biggest fixed 3 blade prop he could. We motored on and off for 10 days together this past fall on the way to Annapolis and if anything my boat was a bit faster despite its shorter waterline and heavier displacement. I was very surprised and so was he.

So, I'm holding off a bit longer before this item hits the top of the priority list.

Roger Block
Shango
PS 40
 
#19 ·
.....
The second friend has a Moody 42 with the same engine as me, Yanmar 4jh2te. He put on the biggest fixed 3 blade prop he could. ...
Selecting the biggest prop is insensible and a probable source of engine problems. The prop needs to be sized to the engine and boat, both in terms of size and pitch.

IMHO, going with a fixed prop on a sailboat which for most of us (except the multihullers like SD) means we have an already relatively slow boat, only makesd sense if you expect to be powering most of the time. With some sailboats, that is a reasonable assuption to make.
 
#16 ·
One other thing to keep in mind whether you go fixed or feathering prop is that either way, its important for the health of the engine to ensure it can reach its specified maximum RPM. Both prop diameter and pitch have an effect on this. The diesel engine forum might be a better place for a thread on this aspect though.
 
#20 ·
bene

If you talked with maxprop, you got good phone support.
They will tell you that you will loose a little less than 5%, under power vs. a correctly sized fixed prop. And you will loose about 15% to 20% under sail with a fixed prop vs their folder.
 
#22 ·
I second svsirius. I've had a 500mm Maxi for 10 seasons with never a failure. It gets greased (and cleaned) annually and shows no sign of wear or failure.

I've had occasion to ask for help from PYI for paint recommendation or to get another zerc plug and always been treated in a 1st class fashion.

I wouldn't challenge for a minute the value of simplicity and in that aspect the fixed prop wins, but in all other regards I would recommend the Max Prop.

Wayne
 
#27 ·
I think the reason for a maxiprop is to reduce sailing drag... Period!!. Pitch and diameter are separate issues. If you have the right pitch and diameter then it is irrelavent whether it's a feathering prop or fixed prop. The feathering prop just reduces tha drag while sailing. It also may have more thrust backing. Most go with a fixed prop because feathering props are expensive. So if it has the right pitch and diameter I'd stay ith what you have. If you don't have enough blade area... cavitating under load then you may need three bledes instead of tow. At this point I recommend Dave Gerr's book "The Propeller Handbook" (in most librarys) which is difinative on all aspects the subject.
 
#30 ·
We had a Campbell prop on Grace for a number of years and it performed quite well. But we replaced it with a Brunton Autoprop and were immediately aware of more power, both forward and in reverse. We replaced the prop to maximize fuel economy and I think it's been a wise choice. I have been impressed with the Autoprop's ability to get me off groundings when I thought for sure I was going to get to know the local TowBoatUS guy.

Sam
s/v Grace PSC34#163
 
#31 ·
"Andante" had a fixed prop when we sea-trialed her, but I switched to a Max-prop. Much better control in reverse.

One problem with Max-props was that the zinc corroded very quickly. Finally, they started shipping little plastic sleeves for the screws along with the zincs and this has corrected the problem. If you get one, make sure you use the sleeves.

Regards,
Karl "Andante" PSC 34 #276
 
#33 ·
I just received a box of 6 maxprop zincs from PYI and they came with hardware that included 2 sizes of allen screws and plastic inserts that appear to fit the smaller size screws. My prop uses the larger screws so don't think the nylon sleeves will work for mine.

John S.
PSC 34 # 201
Norstar
 
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