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Hello all,
I’m about to pull the trigger on a flex-o-fold prop for Blue Moon. I currently have the standard fixed pitch 3-blade, 20″, with 13″ pitch, which appears to be the original set up from the factory. I’m thinking a lot of you are running 19″props (vice 20″) nowadays. Any advice on prop size/pitch? BTW, I have the Westerbeke W58. Thanks!…
David Tye
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David,I saw your earlier post, but since I have a 20″ Maxprop I couldn't offer any information on your Flex-o-Fold selection.
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I have a Wester 58; and replaced the original 3 bladed prop with a flexofold; and, am satisfied with the flexofold prop. Jack, the US contact for flexofold recommended an 18 X 12 – 3LH; and this was too much prop (eng would not reach 3003 rpm, smoked excessively at wot). I downsized; canât find the paperwork, but I believe to a 17 X 11; and, for my boat it is the correct size.
I would touch base with Jack Skrydstrup (jas@flexofold.com); and ask him to id what I ended up with (Robert Kriegel, Pensacola, FL; SV Acadia; Pearson 424 cutter with a Westerbeke 58, Velvet drive model 1017-001; Walter V drive, 2.05:1.
I would also give thought to a Max prop â not as efficient in forward, but superior in reverse. The prop/rudder distance in the 424 makes backing up tough with lots of right prop walk!
Good luck
Bob K
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Thanks to all of you who have responded, this is good poop and much appreciated. I need to determine my full power RPM with the current set up. My tach has been inaccurate since I acquired the vessel, and I have calibrated it recently. Thatâs a data point I hope to get today.
I know the max prop would be better in reverse, and have spoken to numerous owners of other boats who like the max prop. But I really donât want to give up the motoring performance in forward, seeing as how we do more of that than weâd like.
Bob, thanks very much for this valuable info on the flex-0-fold. And belated congrats on your performance on the P-Cola to Cuba race. BTW, there is a talk at the FWYC (Fort Walton) from Dr Piacente on May 12 if you have an interest. You may know this already. If you want to attend this, just let me know. Also, if youâd like to see my Solent stay set up on Blue Moon, just completed, Iâd be happy to show you. Iâm really happy with it so far, and the boat goes to windward better than ever. I know you had some problems with your roller furler in the really challenging weather you faced (Hunter is my sailmaker).
Also Bob, how do you find the flex-o-fold in reverse? As good (?) as the original fixed pitch? A little better (I hope)?
David
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Dave:
Good luck with the prop ing. Reverse â whatâs that. Iâve had the flexofold a year, and have not yet figured out how to go anywhere in reverse except for a sharp turn to the right. I suspect little difference between it and the original fixed prop.
I did not know about the FCYC talk; would have been delighted to attend but will be out of state all week.
We sheared the headfoil the first nite out in the first storm; replaced the entire system with a pro furl. Weather performance â I can go to weather reasonably well if I can overpower the boat without too much heel (use the new 145%); underpowered I just donât go to weather.
Would love to look at your set up, and swap notes. And of course, would be delight to show off Acadia â
Bob K
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We have a 422 and went with a 3 bladed fixed Campbell Sailor (16×11). We hit exactly the specs for WOT and now cruise at 75% WOT at 7.25 kts calm water speed. Very satisfied.
FYI – you can buy an optical tach from Amazon for under $20 that will give you a very accurate RPM. Used it both to calibrate the engine tach and to determine our RPM-Speed curve. Turned out to be a very handy tool to have.
Greg LongSV PaperbirdPearson 422Author, The New Game Changers: Driving Performance by Focusing on What Matters443.995.5551——————————-But if not⦠-
Tor and I have discussed this ad nauseam – in a friendly way, of course. I know there's an attraction to the latest and greatest flippy flappy propellers giving you the extra boost of speed.
But consider this: Moving parts break. Moreover, when they do break it's likely to be the very worst time. Things under the water that move will be expected to break sooner rather than later for so many reasons, not the least of which is that humans are very, very good at 'out of sight, out of mind'.
There are many advantages to a fixed prop – mine, I believe, is a LH22-13, but I could be wrong. It's close to that. 22″ diameter, 13 pitch. Left hand. Since I have the hydraulic transmission (the velvet drive) which has no problem at all rotating (and in fact can't be locked without an external brake), I have rigged an alternator that I can attach with a large pulley on the shaft and belt to generate up to 9 amps continuously at a steady 5.5 knots. True, I lose about a half knot when it's running, but there's no spinning propeller above my head and I need the power when under sail, not when motoring or anchoring for the autopilot and stuff. This rig charges the batteries, runs the electronics and keeps the beer cold.
So that's my two cents. If you're going far away, your flippy flappy prop may do just fine. All the way around the world, in fact. But if it does fail you could very well be screwed. It's a chance I personally won't take.
Bob
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Bob,
How did you rig the alternator to the shaft? Did you attach a pulley/belt arrangement? If so, it seems like it would be fairly easy to add an idler pulley to allow you to disengage the shaft-driven alternator if desired.Can you post/fwd pics of your shaft alternator?Thanks!
Greg LongAuthor, The New Game Changers: Driving Performance by Focusing on What Matters443.995.5551——————————-But if not⦠-
Hi Greg,
Let me see if I can find pictures of the installation – it's currently uninstalled because I don't need it on Long Island Sound.
Here's a link on my blog. http://thesailinglife.blogspot.com/2009/11/georgetown-south-carolina.html I like the idler pulley idea – right now, the alternator rotates at about 10x the prop speed – necessary when sailing, really fast when motoring. I'll have my friend make me an idler. The pulley on the shaft is split – so it's easily removable.
I've estimated that the power generated by the shaft is up to 16hp at full steam (or full sail). That's enough for the job.
Bob
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Hey Bob,
You’re probably all correct. Which widget is “better” usually depends on how you use your boat – cruisers’ needs differ, sometimes widely, from day sailors’ & weekenders’, let alone racers’ (Rich) – on personal preferences regarding the trade-offs (there are always trade-offs) and, of course, budget. I have the fixed 3-blade that came with my boat, albeit re-pitched for the new engine. Had there been a Max-Prop on her or (probably) the one being discussed here, I’d have that. Sometimes the deciding factor is simple inertia.
Tor
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Silverheels, P-424 #17
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I have a Slipstream 3-blade folding prop and love it. The blades are geared together so they open and close in unison. It looks like the flex-o-fold prop isnât geared. I guess it will work OK but youâll find some odd behavior as the blades open, particularly in reverse.
My folding prop works OK in reverse. I have to give it a lot of throttle to keep the blades open. Reverse isnât all that important to me. I donât moor in a slip. Iâm on a mooring. Stopping is important in an emergency. If I give the engine some throttle, she will stop on a dime.
Rich
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Hello Bob,
You have me rethinking a folding prop if I canât expect at least equal performance in reverse as the current fixed pitch (I get that I need to apply more RPM, but pulling strongly to starboard might be an issue). Weâve gotten pretty accustomed to the current fixed pitch on Blue Moonâ¦we can play the prop walk relatively successfully, and frankly, I donât find it that bad. Greg Long, and maybe someone else, recommended the Campbell Sailor fixed pitch. Iâve heard good things about this option, but Iâm concerned about sailing performance with the prop âlockedâ with my Shaft-Lok. And I really donât like to listen to the whine of the V-drive all night. So, a real conundrum, so to speak. I should probably talk to Flex-o-fold, and maybe to Slipstream as well, as Rich Carter suggested. I sure donât want to get stuck with a (backing) turkey at the price I would expect to pay for any of the above options.
On the solent, I will retransmit my latest so that it will go out via e-mail. And if you use the search function on the site (search for âsolent stayâ) you can see my previous postings with some pics of the set up. And of course if you are in Ft Walton, Iâd love to show you Blue Moon.
David
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It’s been many years since I powered my 424 with the original fixed prop. My memory is a bit fuzzy about it but as I recall the thing never backed down worth a damn. In reverse, she had a mind of her own, resisting attempts to steer in any particular direction. Yes, you can play with forward and reverse and use the tendency to back to starboard to nurse her stern around and forward to nurse her nose, but the rudder does nothing to help in reverse. I’m not sure that the folding prop is any worse than the original fixed prop. In the interest of full disclosure however, I don’t do much backing.
Every once in a while I cruise with my club and find myself assigned an inside slip down a narrow fairway. I usually don’t find it difficult to get myself in the assigned spot but getting back out is sometimes difficult. If wind and current are light, I can get myself out without embarrassment, but if there’s a crosswind, I’m like a loose-cannon. I’ve been known to send someone in the dinghy to push us around.
Stopping with the folding prop is not a problem. If I give it some throttle in reverse a whirlpool comes out both the port and starboard sides of the boat and there is a sucking sound from both cockpit drains. The boat stops dead in her tracks.
There are a lot of lobstah-pots in the area I cruise. With blades folded, there isn’t anything down there to snag a line. That’s nice. Under sail you can just enjoy the boat and not worry about zig-zagging around pots. I removed the brake years ago. With the blades folded, there is no worry about free-wheeling.
Rich
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Hello Rich,
Thank you for the words of encouragement. Tell me this: how do you get your blades to fold? With our free wheeling transmissions, I perceive this to be a problem. My solution (in my mind, anyway) is to âlockâ the shaft with the Shaft Lok at a very low forward speed. The Shaft Lok is not a brake, and can only be activated with the prop shaft turning pretty slowly. Curious about your experienceâ¦
David
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Thanks Warren. My wife has been eyeballing the Gori. How does the Gori do in forward? And how do you get your Gori to fold?
David
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David,
To fold it we just sail. Because of the way the blades fold I think even at minimum rpm in reverse the blades would partially open in the reverse configuration.
In “normal” forward it seems to work fine. In reverse, the blades still present the power face to the water. If you build up a little sternway, then gently slip into forward, the water pressure from moving astern keeps the blades open in the reverse configuration. They are now presenting the back side of the blade to the water when you shift into forward, but the back side has about 2 inches more pitch then in the forward configuration. Gori refers to this as the “overdrive” and at low to intermediate rpm it will give you about 20% more speed for a given rpm, or you can back down the rpm and maintain speed at about 20% better mileage. I’ve tested it, and it really works. But (assuming your prop is correctly pitched) you will not be able to maintain the 20% advantage at full rpm, and you will overwork the engine.
Warren
s/v Adagio
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Rich,
Seems like if you shift into reverse while sailing at any speed, you could damage, even break, the transmission. Even if the engine is idling in neutral when you do it, the tranny will be spinning “in forward” as fast as the prop is freewheeling. The only safe way I can think of to do that is to first slow the boat down by luffing up so that the prop is turning very slowly.
Tor
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