Are folding props worth it?

[uncledom]

Originally Posted by a64pilot

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.

You are correct, this prop requires attention. I just did a rebuild this spring. Five seasons of grease. It was about 400 to buy the parts and the video is online to do the servicing. A vise is needed, he pre-loosens everything off camera. It was not hard or time consuming, about two hours for my first time.

[Ardbeg]

Not sure if I have feathering or folding. It is a 3 blade where blades fold with water. I assume folding. I got a knot more speed. in 15 knots wind under full sail, I will now be doing between 7-8 knots, sometimes over 8. I put gear in reverse when sailing. With original prop I would get vibration on cockpit floor whenever I went over 6 knots. Now nothing. The other huge advantage was prop walk. I can go in reverse in either direction, ( Port or starboard) as if I am going forward. With the old rigid 3 blade, I could not reverse to starboard. So I swear by the $3000 expenditure. Also I very seldom motor when outside of marina.

[kenckar]

Originally Posted by singlespeed

I switched out a pair of fixed three bladed screws for a pair of Kiwi Props on a Lagoon 42 TPI. Lost about 1/2 knot of motoring speed in the same conditions, ...

Loss of motoring speed is not universal. I wonder if a higher pitch might have helped.

[Exile]

I wasn't aware that a folding prop could reduce if not eliminate prop walk when in reverse. Anyone else have this experience? Or not? Could be worth the price of admission for me if this was the case on my boat. (I have a fixed 3-blade from Mich. Wheels).

[daveball]

Major disadvantage(s) of a fixed prop, noise. This was solved by employing a shaft brake. I our case this consisted of a length of webbing material wrapped around the shaft and secured to a cleat. Eliminating the noise made sailing much more enjoyable. The other disadvantage was maneuvering in reverse with a full keel. Tricky to say the least.

[Scubaseas]

Originally Posted by Exile

I wasn't aware that a folding prop could reduce if not eliminate prop walk when in reverse. Anyone else have this experience? Or not? Could be worth the price of admission for me if this was the case on my boat. (I have a fixed 3-blade from Mich. Wheels).

For my boat the Flexofold did reduce prop walk in addition to providing much more thrust/stopping power in reverse. But then I miss the prop walk as it can be helpful to have it if you know it's there. Plus I have to unlearn how to drive the boat. With an adjustable feathering prop you can dial in the amount of pitch so you can effectively set what prop walk /thrust you want. If your boat backs up like drunken elephant with a fixed prop it may still do so with a folding prop but probably to a lesser degree. The extra stopping power of a folding or feathering prop can be very nice indeed to have in stiff winds/currents.

[henryv]

Going back to the original question. I have a PDQ32 with the tilt up outboard engines. In the 12 to 15 knot winds mentioned in the original post I will sail in the 8 to 10 knot range or better depending on sea state. While the LRC would still have some drag from the drive legs I would certainly expect a nice speed pick up from going to folding props.

[Cheechako]

Originally Posted by captmikem

First off, feathering (maxprop) is MUCH better than a folding prop.

If you are the typical intracostal cruiser (motor 90% of the time) then no, not worth going with a folding/feathering prop unless you are racing. If you are making long passages, crossing oceans, they are definatly a plus. 1/2 knot is 12miles in a day , or up to 3 hours a day for the typical cruising boat.
M

Totally agree.

[kenbo]

Originally Posted by henryv

Going back to the original question. I have a PDQ32 with the tilt up outboard engines. In the 12 to 15 knot winds mentioned in the original post I will sail in the 8 to 10 knot range or better depending on sea state. While the LRC would still have some drag from the drive legs I would certainly expect a nice speed pick up from going to folding props.

Very informative post for the OP. I usually shy away from posts like props and anchors because of the strongly held opinions and too many variables to cloud the results. But here are some things I've learned along the way, some the hard way.

You should have a good feel for your running gear and cruising habits before selecting a prop, especially shaft RPM. Flat bladed feathers like Maxprop suffer from cavitation beginning at around 900 RPM. That's why some experience blade pitting and others do not. High reving diesels without much reduction are typically not a great match for flat bladed feathering props. I have to give credit to Steve Dashew for figuring this out.

Dreams of the ideal propeller can be dashed if the vendor doesn't get the sizing right. Advantage featherers, if you get a folder make certain and in writing what your recourse is if not sized properly.

Kiwiprop is a great sailing prop on a number of fronts. It's light, smooth, offers a perfect galvanic match to your shaft (if SS) and relatively inexpensive. It's major flaw is it's significant loss of propulsion and motoring speed due to blade shape. The manufacturer is modifying the blades shape to give some additional lift but it still falls short in this regard. Something to consider if you motor a lot and fuel range is important.

I'm open to dissent on prop walk, it's origins and whether you like it or not. But I've always thought that it was caused by the force of the water being pushed against one side of the hull or the other depending on prop rotation. So everything else being equal, which it may not be, a prop that produces more thrust in reverse (like Maxprop) and pushes more water against the hull should produce more sideways motion not less. So the controlling factor seems to be the nut that holds the throttle lever, just like in cars it's often the nut that holds the steering wheel

[a64pilot]

Originally Posted by Exile

I wasn't aware that a folding prop could reduce if not eliminate prop walk when in reverse. Anyone else have this experience? Or not? Could be worth the price of admission for me if this was the case on my boat. (I have a fixed 3-blade from Mich. Wheels).

My Autoprop eliminated it completely, I believe prop walk is proportional to pitch, and an Autoprop in very low speed or reverse conditions goes to min pitch, and therefore nearly zero prop walk.
I miss it, I wish it had more prop walk. Once I got used to it, it was my poor mans bow thruster.
With my fixed prop I had epic prop walk. Cause the boat was way over propped, turned 2400 Max out of 3600, but made 8 kts, which is all she can do even when properly propped. Odd thing was it didn’t smoke, but you know that’s bad on the engine.

Point is if you eliminate it, you May miss it, I didn’t think I would as I could not back straight, but I do miss it. I used to could back some and a quick blast in forward to bring the stern back in line, back some etc.
Now if there is wind, I’m backing into the wind

[mawtty]

By far the best are feathering propellers.
You can adjust the pitch to suit your boat.
Reverse thrust is as good as forward thrust.
Very little drag. Makes a big difference to sailing upwind performance.
Only drawback compared with folding props is their ability to catch lines.
mawtty alias (Honourable Horatio Hornblower the Horrible)

[Zzmeyer]

In the Yachting Monthly test, the 4 of the 5 fastest props were folding props. Folding props had more forward thrust and less prop walk than feathering props. Feathering props did better in reverse and stopping distance. The ability to adjust a feathering prop is only valuable if the prop is not correctly pitched to begin with (albeit an event that occurs frequently). While the feathering prop has significantly less drag than a fixed prop it has more than a folding prop. The feathering prop is also, in general, more expensive. Having had about a half dozen of both the only two times I caught a line on the prop was while motoring with a folding prop. You won't catch a line while sailing and folded, though.

[Exile]

Assuming proper pitch, I'm having a hard time understanding why prop walk in reverse would be reduced over my fixed prop, whether it's a feathering or a folding prop. Like a64, I've adjusted and learned how to deal with prop walk, but it'd be nice if it was mitigated somewhat. As it is, I can use it to my advantage in tight maneuvering, but trying to make any distance in reverse (occasionally required in tight marina fairways) is usually a non-starter.

I've also heard -- maybe more so with folding vs. feathering props -- that there can be some not insignificant delay when shifting from fwd to reverse gear. If true, then this could also be a non-starter for me.

[Zzmeyer]

The above shows the results from the Yachting Monthly prop walk test. Note that one fixed prop is the best, the standard one is only so so. I've read that the feathering prop is the best in reverse because the leading edge is generally reversed when you put it in reverse making it more efficient than a reversing fixed prop that has its trailing edge leading. This would likely affect prop walk.

[sailorboy1]

My FOF has both forward and reverse prop walk at low rpms. I don't understand everyone seems to get rid of it as I find it more useful than a problem