feathering and folding propellors - opinions

[Bosun Higgs]

Currently got a Radice folder which vibrates like a road drill if I put it into reverse when going forward. They all do that says the agent, and true there is nothing much apparently wrong with it. So maybe I need to replace with a better brand.

Would be interested in hearing about people's experiences of other makes, both folders and featherers, particularly if they have changed ove from ( say) a fixed prop and can give a comparison of performance.

Boat is used for both cruising and racing so a fixed prop is out of the question.

 

[oldsaltoz]

feathering props have more grip in fwd and rev than folders making them more economic to operate, they also last longer with no cogs and pins to fail.

 

[flaming]

Currently got a Radice folder which vibrates like a road drill if I put it into reverse when going forward. They all do that says the agent, and true there is nothing much apparently wrong with it. So maybe I need to replace with a better brand.

Would be interested in hearing about people's experiences of other makes, both folders and featherers, particularly if they have changed ove from ( say) a fixed prop and can give a comparison of performance.

Boat is used for both cruising and racing so a fixed prop is out of the question.

Parked a lot of boats that have folders, plus have a bunch of experience with fixed props. Never actually sailed a boat with a feathering prop, to my knowledge.

Vibration - never, ever, had that problem and would not accept it. I know I've used volvo and bruntons (I think) folders, but almost certainly used many others on a variety of saildrive and shaft drives. (make of prop is not a question I tend to ask to be honest!)

General handling - Some are better than others, especially when it comes to reversing. But despite the fact that I've been known to manouever race boats in 30+kts quite frequently, and 40+ on occasion I do not subscribe to the old addage that folders give dodgy handling, and having a folder in those situations has never had me drastically changing my methods.

 

[Marsupial]

I ve had a Maxprop on Jeanneau 37 and found it to be very difficult to get the pitch right, also the gears and bearings looked a little light, but who knows perhaps they are ok. As a result of that experience I chose a volvo 3 blade folding prop for the next boat and have been very pleased with it, and yes it does go astern. The gears and pivots are far larger than those on the maxprop and I would not expect them to wear quickly.

Under power the prop is using all the engine power and is therefore economical, no judders or vibrations.

Under sail there is a great performance advantage in light airs - hard to put a number on but I would guess at around 1 knot, certainly the boat acheives hull speed under sail much quicker with the volvo prop than with the fixed 3 blade the boat was born with so there is a lot less drag.

I am not a fan of volvo engines but I recommend their folding props and stern glands.

 

[nibby david]

why don't we utilise prop drag as a generator?

Having recently read on the Catalac forum the data on tests of locking a propellor or letting it freewheel with amazing results in favour of drag reduction by freewheeling has made me wonder why nobody has thought to rig up a car alternator (or two on a catamaran) via properly ratio pulley v belt system wired in tandem to the engine alternator electrics.
OK, most solar and wind generators are great for trickle charging batteries, but the towing water type of generator are very expensive, but the need for decent amperage on ocean passages does require frequent engine use.
Working on the principle that we try all manner of expensive folding prop to reduce drag, whilst not thinking that a freewheeling prop as an efficient turbine which could be used to generate a lot of free electricity, certainly enough to power on board electronics/fridge and auto pilot?
Any thoughts on this OR has anyone actually tried to do this?

 

[snowleopard]

feathering props have more grip in fwd and rev than folders making them more economic to operate, they also last longer with no cogs and pins to fail.

Agreed in reverse but in fwd a folder is the match of any other type.

Early folders were pretty primitive but today's models with heavy blades open well in reverse. My boat will stop in less than its length from 10 knots using full reverse.

 

[smth448]

I have always used a folding prop since having a feathering one years ago which gave no end of problems. It came with the boat and the surveyor did say it was knackered.
No problems ever with vibration so I think you should try elsewhere to get it fixed or just yell at the agent. It may be that one blade is not opening fully in reverse.

I have seen some folding props that are absolutley useless in reverse so you have to be careful. I remember a 3/4 tonner with avery expensive folding prop that formed a perfect tear drop shape when sailing for minimal drag. It would stop the boat in full reverse from a couple of knots in about half a mile!

 

[Tranona]

YM ran a "test" on folding and feathering props about a year ago.

The general conclusions are that Feathering props give the best overall performance under power. Folders give the least drag, but generally give poorer motoring performance. However, this difference has become less with newer designs of blades and introduction of 3 bladed folders.

I think you will find a Flex O Fold (which did well in the tests) or a Volvo 3 blader (which was not tested) will be a significant improvement on your current prop. In the Feathering category the Max Prop is probably still the best, but the Featherstream also did well and is substantially cheaper. Bruntons has a good reputation, particulerly among those who value good motor sailing performance.

As with many products there is a lot of choice because it has become a very popular thing to waste one's spare cash on and you will find supporters for just about every brand. There is plenty of information and advice available from manufacturers and importers to help or confuse you. All will be pleased to take your money!

 

[Marsupial]

feathering props have more grip in fwd and rev than folders making them more economic to operate, they also last longer with no cogs and pins to fail.

Err quite a few cogs and pions to fail (IMHO) try wiggling the blades on a maxprop that has seen a bit of service to see what I mean, and have a look here to see the little cogs and pins thatt wear out.

http://www.pyiinc.com/index.php?section=max-prop&action=three-blade-classic-installation

 

[snooks]

Currently got a Radice folder which vibrates like a road drill if I put it into reverse when going forward. They all do that says the agent, and true there is nothing much apparently wrong with it. So maybe I need to replace with a better brand.

What's your bottom like? Any skeg there?

Do you have 2 or 3 bladed prop at the moment?

If you have a skeg it could be this. Nearly all the props on the test we did, vibrated like you describe during our emergency stop test

 

[Sans Bateau]

Something that has not been mentioned, I feel strongly that a folding prop is less likely to collect weed or worse still a piece of rope or fishing net than a feathering prop, which of course still 'sticks out' when you are sailing. Seeing we are more interested (or should be) in sailing than motoring, then this is something that should be given due consideration.

 

[Tranona]

Whilst that may be true when sailing, I would suggest that most debris is caught when motoring because that is when the water flow draws the debris down into the propeller.

 

[EdWingfield]

I replaced a fixed two blade prop with a 3 blade Kiwiprop and have used it for a season.

Results are: no rumbling noise as the shaft no longer rotates at 5kn+, Greater propwalk in both fwd and rev.

And I hope greater fuel efficiency under motor. And I hope less drag when sailing (although both these I've not been able to measure and prove)

 

[BlueChip]

Currently got a Radice folder which vibrates like a road drill if I put it into reverse when going forward. They all do that says the agent, and true there is nothing much apparently wrong with it. So maybe I need to replace with a better brand.

Would be interested in hearing about people's experiences of other makes, both folders and featherers, particularly if they have changed ove from ( say) a fixed prop and can give a comparison of performance.

Boat is used for both cruising and racing so a fixed prop is out of the question.

I had a volvo 3 bladed folder for 5 years and then a flex-o-fold 3 blader for the last 10 years. I have had absolutely no problems with either and they provide plenty of thrust ahead and astern with no vibration.
The prop comes apart easily for cleaning at the end of each season and theer is almost nothing to go wrong. I'd buy another and can see no reason to pay a lot more for a feathering prop.

 

[snooks]

I'd buy another and can see no reason to pay a lot more for a feathering prop.

On your boat may be, but on boats with a aperture where the prop is, CO32 for example, or where the prop is close to the rudder, a feathering prop is the only alternative

 

[Bosun Higgs]

What's your bottom like? Any skeg there?

Its a shaft log not unlike the one you show in your video, and the current prop is a 2 blade folder.

Someone once did make the comment that the vibes could come from the blades passing behind the shaft log every revolution ie not having a consistent water flow through the whole 360 degrees.

Which oif your test props didnt vibrate during the emergency stop?

 

[HinewaisMan]

Nearly all the props on the test we did, vibrated like you describe during our emergency stop test

Respectfully I might suggest that the vibration you're feeling when going into high rev reverse is cavitation. Prop killer.

We swopped our 23 inch fixed three blader for a 3 blade Slipstream folder. A great propellor. Huge difference when sailing and more power when motoring forward. Stopping? Well, you have to get used to a gentle (albeit not slow) application of power - but she stops our 18 tons OK

 

[shaunksb]

I feel strongly that a folding prop is less likely to collect weed or worse still a piece of rope or fishing net than a feathering prop.

Absolutely. We got a thick rope/5ltr oil can round the keel/prop motorsailing on the way back from Isle of Man last year. Almighty vibration as part of it got sucked into the prop but I suspect it was trying to push the prop shut and we eventually cleared it.

 

[brianhumber]

Had a Radice on UFO 43 which wrecked itself. Then tried more expensive Gori and differnce in quality was massive.
Thus very satisfied with Gori and put on one Ronhilda over 10 years ago and pushing 20,000 miles ago . Only thing that has worn/required replacing over the years has been the small anode ( every year) and pastic bump stops ( twice) . Machining is such that removal after being on shaft for 5 years was half hours work with supplied tools - none of this pissing around with external pullers and arms that do not exactly fit etc
Bottom line is you get what you pay for, and I would not hesitate to buy again.

Brian

 

[snooks]

I'll contact the author to see if they made a note of the vibration at the time.

The vibration on 2 bladed props was much worse than the 3 bladed props because of the shaft log. We were aware this would be a problem with the test as it's a quirk of the shaft log, which is why we didn't dwell on it in the test.

"She has a typical fin keel form, but atypically she has a built-in skeg carrying the shaft, {snip}
The skeg protects the shaft and prop from underwater damage, but a downside is increased vibration as the blades of the prop pass through the disturbed waterflow behind the skeg. This is resolved in normal use by fitting a three bladed prop as standard"

The skeg also increased vibration while going astern.

I think (again from memory which is from March 2009) the Bruntons Autoprop was the smoothest, but it was also one of the most expensive.