I note that is”trying to catch La Reina”
Mark Powers
La Reina (that pesky, speedy) 26C
Vancouver, B.C.
Paul:
I have sent this out before...but here is the link to the best two articles I have found on this whole subject. The first is by Nigel Calder and has the most info on achieving best fuel efficiency. The second is by Emrhys Barrell in Yachting Monthly and does a great job on head-to-head comparisons of 13 different props (...don’t miss the charts and graphs toward the end):
https://www.mysailing.com.au/gear/folding-prop-gear-test
https://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807
I was a bit surprised that Nigel didn’t make a more determines effort to correctly match each prop in size and pitch for his particular Malo boat. Evidently, the various manufacturers weren’t willing to provide that big a variety of their props, and for his particular torque/fuel flow measurements, it apparently isn’t critical, but his results don’t single out a Best prop.
On the other hand, Emrhys clearly shows that any fixed pitch prop, in or out of gear, creates a drag bucket that adversely lowers hull speed and fuel efficiency by at least a knot and 15%. While a number of the other props, both folding and feathering, shone in one way or another, the folding Danish 3-blade Fexofold was the clear overall winner, providing the highest forward speed at lowest RPM (...thus less fuel burn) with decent reverse and minimal prop walk. Also, he makes a good point that any of the folding props are far less likely to snag any floating lines or netting, at least while under sail, than are the projecting blades of either a fixed or feathering prop.
The shorter Nonsuches have such low hull speeds that giving up a knot just to prop drag under sail seems rather illogical.
Fair winds,
Barry Stott
Chadds Ford, PA
ebstott@aol.com
Thanks Barry.
I read the articles when you posted them in your first post. Please don’t take this the wrong way but I don’t really have any interest in switching to a feathering or folding prop. My boat stays in salt water all year round. I don’t want any moving parts that may require expensive service due to barnacle intrusion, corrosion, or wear. I have always used fixed two bladed props and I am more than happy with them. My experiments were conducted and posted simply as observations.
My two bladed prop gives me good power and decent economy and just enough prop walk to be useful in tight maneuvering and docking. I have good stopping ability as well. The only place I may lose a little is speed under sail however I highly doubt it is as much as you are implying.
I have a Nonsuch. I pass a lot of boats. I’m happy.
Paul M
NS30U #211, Sandpiper
Cowichan Bay B.C.
Hey, Paul... didn’t mean to criticize your choice. You’ve obviously given it serious thought and made a logical decision that works for you. Sadly, I am a bit more anal about this than you are... and if I could eke out another half a knot to ghost past some guy with two or three sails flying, I’d snicker in delight.
Also, if you ever decide to sail down to the Caribbean, you’d soon wish you had even waxed the bottom!
Barry
A few words of caution on the Yachting Monthly Test. They do not give the engine rpm. Based on my reading of the Yachting Monthly and other prop tests the Flexofold props were oversized for the engine. The engine could not reach it rated speed. The oversized prop as Nigel Calder points out gives good numbers but has the potential to damage the engine and may void a new engine warranty. When you read the Yachting Monthly test you see that Gori felt they had sent an under sized prop. In the Voile test they sent a bigger prop and it preformed at least as well if not better than the Flexofold. At least one individual has had a problem with his Flexofold not opening all of the time. He has posted a number of articles on You Tube about his dealings with Flexofold over the issue.
The transmission on the boat in the YM test had a higher numerical reduction in reverse than in forward and the tester pointed out that this may have hurt the folding props. If that is correct the folding props might preform better in reverse on a boat with a different transmission.
As I stated before La Reina came to me with a two blade Max Prop. I have used that all of the time I have owned her except for one year when I sent the prop off for service. During that year I used the factory 2 blade fixed prop. The fixed had less prop walk and I could not really detect a difference in sailing speed. The Max Prop gives more thrust. A real advantage of the fixed prop is cost. The initial cost is significantly less and with a fixed prop a diver can give it a clean. In order to service the Max Prop, the boat has to be hauled out so it can be lubricated. Many people on the west coast use a multi season bottom paint and haul the boat every second or third year. In between they hire a diver to clean the bottom and change zincs. La Reina gets hauled each year which is considerably more expensive than a diver. The Max prop is now 38 years old and has about 2700 hours on it and it is still in relatively good condition so longevity is not an issue.
The Max Prop has adjustable pitch. They give the pitch in degrees not inches. The prop I have was pitched and sized correctly for the Westerbeke 13 La Reina originally came with when set at the equivalent of 11" of pitch. With the Beta 20 it is slightly over pitched at the 11" setting and under pitched at the next setting down (about 9.5"). 10" for that prop would be about right. Both transmissions have 2:1 reduction ratios in forward.
I do not recommend one propeller over another. I suggest to people that they might investigate some different ones and read as many tests as possible but to read the test results carefully.Read them for as much as what they don’t say as for what they do say. I do however make an exception with Paul Miller. I keep suggesting he get a 19’ fixed four blade with 19" of pitch, however he insists on sticking to a smaller prop.
I have made another attempt at attaching the Voile tests results.
Mark Powers
LA Reina 26C
Vancouver, B.C.
(attachments)
Voile test 1.pdf (310 KB)
Voile test 2.pdf (103 KB)
Mark and Members:
This is obviously helpful info, but what we really need is a spreadsheet statistical database of boats, engines, prop types/sizes/pitches and performances. Then each class (size) of Nonsuch could see and analyze where they stand.
Anyone willing to set this up and implement it?
Barry Stott
Chadds Ford, PA
ebstott@aol.com
Barry, no offense taken (or meant). As far as ghosting and bottom waxing goes, I’m afraid I’m the kind of sailor who prefers wind. If there isn’t any I’m more than happy to run under iron topsail. I am fortunate to live in one of the few places in the Canadian Gulf Islands that has wind just about every day in the summer.
Mark, not sure that prop would fit without a few alterations to my hull. .... 
Paul,
you have the skill set to make those modifications. By the way, Maple Bay often has wind as well.
Barry,
I thought brilliant suggestion. We would have to decide what data sets we gather, water salinity and temperature plus ambient air temp for sure. Weight of vessel as tested, power curves for the engines, date of last service, oil test results and compression test to ensure the engines are making the rated power. Transmission ratio, sail driver, straight drive, drive or outboard on the 22’s. We could ask the Canadian government to give us a research grant. Then I thought we already know that for ghosting past someone you need an outboard that can be lifted clear of the water or else a folding prop. Alternatively you need an electric motor, al la Captain Mike. If we are talking about motoring, a clean bottom and a clean prop probably make a bigger difference than the prop you choose. Oh well, another great project that will never leave the dock. May as well go sailing.
Mark Powers
La Reina 26C
Vancouver, B.C.
Mark, don’t forget Ganges Harbour either but they are few and far between.