Are folding props worth it?

[longjonsilver]

Originally Posted by sailorboy1

You people should spend more time reading tests and less time reading marketing spin

You mean like this one?

http://www.hughes38.com/wp-content/u...onthly_low.pdf

jon

[bobnlesley]

Originally Posted by breezydays

Like most things it does depend on what kind of sailing you’re planning. For us cruising ... a big difference over distance .

But if you're planning to sail off the beaten track too, then be sure to take the original fixed bladed props along with you, they can invariably be repaired in the boondocks anywhere that there are fishing boats, but the folding/feathering varieties perhaps not.

[Zzmeyer]

The best prop review I've seen is the Yachting World test
https://www.yachtingmonthly.com/gear...ler-test-29807
There is a german language one also, and the results are quite different so maybe a bit of caution here. If you look at the tests there is no "best" type of prop. The standard three bladed prop is an excellent powering prop and is most cost effective but suffers greatly with drag.. The feathering has more drag than the folding prop but tend to be better in reverse. If you look at the results Flexofold is best in max speed and near the top in forward thrust while the max prop suffers from prop walk and shines in backing down. I'v had fixed, flexofold, martec and maxprop. The martec couldn't back down to save its (or my) life. I loved the maxprop and was reluctant to switch to the flexofold. Having switched I'm going with flexofold again. The big thing I learned in the two articles is the prop you choose is very important (diameter, pitch and actual prop configuration). The difference in thrust between the right prop and the wrong prop is often greater than the additional thrust of an engine upgrade.

[sailorboy1]

There, in just a few posts two people who have had both a Max Prop and a FlexOFold. Real life use and both vote FOF. This reverse and prop walk thing are over blown. I am more interested in the prop going forward and having low drag. I don’t really want a prop with no prop walk because prop walk is useful. I’ve never had a problem using reverse to stop the boat ever.

With years of real life use with each- FlexOFold with no doubt

[Jerry Woodward]

The Flexofold does look like a really good prop and one thing that occurred to me reading these reviews and looking at the pictures is that the folding props, when folded during sailing, should have much less propensity to snag lines from crab and lobster pots. In just two seasons of sailing between Punta Gorda and the Keys, I have snagged crab pot lines on my props three different times requiring me to dive down and cut the lines, once in pretty rough conditions. All three times I was sailing and the engines were not running. But the props were free spinning and the lines were seriously wrapped. If a folding prop had less tendency to snag lines, and it looks as though they would while sailing, that would be a big selling point for me.

[Jim Cate]

Originally Posted by captmikem

Max prop is more efficient, blades are designed to push water (rather than designed to fold flat). Less area presented when feathered, able to change the pitch, no possibility of a blade sticking folded, no vibration, works very efficiently in reverse, 3 or 4 blades, easy to clean when in the water ( stable blades you can push against and scrape).
M

Mike,much as I respect your opinions, I can't agree with this or your previous post.

Max Props and all other conventional feathering props are LESS efficient than a F0F or other well designed folding prop. This, as has been endlessly discussed in previous threads, is due to the flat, untwisted shape of the feathering prop blades... something required for them to work in both rotations. This is obvious in theory and in the published results of many objective tests... and in our experience and that of others, as reported upthread.

It is true that feathering props generate greater static thrust in reverse than either folding or fixed props, and if that is important to one's sailing style, so be it.

As to drag, published tests show most folders to be better than any feathering props, contrary to your claim. All better folding props have the blades geared together which eliminates the stuck blade concern you note. And as to ease of cleaning... well, I guess that could be true, but in practice I've not ever noted much difference. And don't forget that folders while folded are much less likely to collect weed or lines than is a feathered prop.

A further note is that in previous threads, folks have reported having to have their Max props rebuilt after only 1200 to 1500 hours. This in itself eliminates them from my consideration. When we did try a feathering prop, we found the Australian Auto Stream to be considerably cheaper than a Max, and it was still working well when we sold that boat some 4000 hours later... with no service other than injecting grease via its Zerk nipple.

We've now used two and three blade fixed props, two and three blade folders, (Martec, Gori, and FoF) and one three blade feathering prop. The FoF is the clear winner in our experience, in all aspects save static reverse thrust, It was not cheap, but less expensive than Gori folders or Max feathering props.

Jim

[SteveSadler]

If you don't motor much and have a bow thruster,sure, use a folding or feathering.
But I've used folding props and in close quarters it's a big compromise, thrust can be minimal, prop doesn't always open in reverse. Also fuel consumption goes up 15% -20%
Wrap a chain around it and it's done! Not for a cruising boat. Been there, I'll keep my fixed prop and let it freewheel and still did 3000mi in 17 days under working sails.

[Jim Cate]

Also fuel consumption goes up 15% -20%

Not if you have a good folder and well matched to engine and transmission. Quite the contrary in many cases. See results of objective tests referenced in various posts above.

And we've had folders and feathering for some 32 years and around 140000 miles with none of the issues you suggest.

Jim

[Martkimwat]

I originally replaced my fixed three blades with a two blade Flexofold. Had improved sailing speed, (about a knot extra) and powered speed was not affected, however, my speed astern dropped significantly and more importantly, the ability to slow down quickly was impossible. Since my boat lives on pile moorings with often a significant cross tide and/or crosswind, that was important for me. Admittedly it was not helped by the bizarre fact that all small Yanmar engines have a very low reverse gear ratio (3.1:1) compared to their forward gears (2.1:1 or 2.6:1) which just made matters worse. I ended up changing to a three blade Featherstream. Now I can stop reasonably well, certainly no worse than with the fixed three blade. My forward drive is slightly less than the folder as well as fuel consumption (obviously) but I can still do hull speed under power and keep up with or motor faster than similar boats, so I am happy and my sailing speed is no different than with the folder.

[belizesailor]

Originally Posted by Jerry Woodward

The Flexofold does look like a really good prop and one thing that occurred to me reading these reviews and looking at the pictures is that the folding props, when folded during sailing, should have much less propensity to snag lines from crab and lobster pots. In just two seasons of sailing between Punta Gorda and the Keys, I have snagged crab pot lines on my props three different times requiring me to dive down and cut the lines, once in pretty rough conditions. All three times I was sailing and the engines were not running. But the props were free spinning and the lines were seriously wrapped. If a folding prop had less tendency to snag lines, and it looks as though they would while sailing, that would be a big selling point for me.

They do have less tendency to foul. Feathings will foul.

[Alis]

Folding props are by no means optimized for performance under power, but they do keep your tranny from turning under sail and that's a good thing.

But they also offer an advantage that fixed bladed props (or even to some extent feathering props) don't offer; they are far less likely to get fouled on a net line or crab pot line while under sail. They won't wrap the line up around the shaft because it's not turning, and the folding prop offers a very low (and somewhat smooth) profile for when a line does gets dragged across it.

I always feel more comfortable sailing the Chesapeake knowing if I accidentally run over a crab pot line I won't snag it with a turning prop. That's the main reason I've always had one on my boats over the years (C&C 41 and Hunter Legend 40).

[Zzmeyer]

Folding props: I wouldn't underestimate the power/speed potential or overestimate their ability to avoid fouled props. The Yachting World test makes it clear (to the extent you accept their test) that a well designed folding prop has both the power and speed to compare favorable with a fixed prop. Likewise, by experience, I know that a folding prop, while powering is able to wrap a line. While I've probably avoided a couple lines that folded a prop and slid off I've also wrapped a couple times. Totally correct that while sailing the obvious shape advantage avoids most lines. I went with folding because of improved sailing performance. I went with maxprop and now flexofold because their performance under power was equal to, or better than, a fixed blade alternative.

[Scubaseas]

I have had both fixed three blade, Autostream feathering three blade and Flexofold folding three blade props. No question the Flexofold is better IMHO. Less area to snag crab/lobster pots which a feathering prop can actually do. Ask me how I know this. The Flexofold gets the best fuel economy of the three in "overdrive".

Reverse thrust is highest with the Flexofold. Then feathering. Fixed sucks in reverse.

The feathering one was adjustable in water. Flexofold is not adjustable unless you send it out to get the blades bent.

If you have a fixed prop freewheeling it will accelerate wear on shaft seals/stuffing box and bearings. Not much but it will. If you lock it some transmissions will wear out the friction surface of the gear quicker. If you free wheel you get to listen to the noise which can get silly running downwind in big seas and surfing.

You may gain 1/2 to 3/4 knot using either folding or feathering over fixed. YMMV.

[uncledom]

I purchased a Brunton's AutoProp. More than a knot of speed enhancement while sailing, the most awesome motor sailing I have experienced, and almost no prop walk. You also get full thrust in reverse. It was expensive but it pays for it's self every time I use it. I stop the engine in gear after the sail is up and then put it in neutral. That's just enough time to get the blades to really feather, not take a least pressure angle relative to it's mount but to actually take the least pressure angle relative to the water and the boats direction. Best 4k I ever spent... well aside from the engagement ring.

[a64pilot]

Originally Posted by GTom

I was wondering how much service these props need? Obviously no one wants a prop stuck folded right before a rough harbor approach.

Some very little, I think the Kiwi prop almost nothing beyond cleaning, but I’ve not had one.
A Brunton’s Autoprop is the other extreme, it needs regular inspection and maintenance (greasing) this can be done when you dive it to clean it, but if you don’t keep to serviced it’s going to cost you.