Why not just a folding prop?

[Sans Bateau]

I cant see that there is a particularly strong argument for a feathering prop.

Agreed it will be a vast improvement on a fixed, offering less drag under sail. But although there may, depending on the make, be more thrust under power than a folder, the folder has the distinct advantage of being nicely tucked away so as not to catch any nasty bits of rope or nets that might be floating around. A feathering prop surely can still catch these hazards, cant it?

 

[flaming]

Folding props are seen as the "racing" option. Some people have a deep aversion to anything at all associated with racing!

 

[Robin]

A feathering prop will provide minimum drag under sail but also minimum thrust under power and especially in reverse. It might pick up less floating junk than a feathering prop but if it did then it might refuse to open when needed. Our current boat came with a Brunton feathering/self pitching prop and a rope cutter and we have had no problems in 10,000mls so far even with an exposed shaft 'P' bracket configuration. What is 'telling' is that we also inherited the original folding prop as a spare, says it all!

 

[Evadne]

Aren't feathering props more responsive, a folder having to "spin up" in order to open, especially when trying to engage reverse from going forward?

 

[Sans Bateau]

mmm I cant see how a rope or in fact anything could foul a folder prop, folded, what could it catch on?

We have always had a folder, I was thinking of changing to a Bruton, but can I justify the price? Our old (Volvo) folder opens easily in forward and reverse, drives us at about 7knts (with a clean botty) at 2500 rpm and does what I expect in reverse. In fact it has just a little kick to Stb in reverse which can be put to good use when entering a tight berth.

 

[TiggerToo]

if it aint broke dunt fixtit!

but when it does break (and Volvos do have a reputation for loosing their blades) consider a feathering one with a good rope cutter. We have a Kiwi with and Ambassador. The combination works well (yes, someone did try the rope cutting action on one of my new mooring ropes /forums/images/graemlins/mad.gif). It is just a little disconcerting that the propeller was only twice as expensive as the cutter...

 

[Sans Bateau]

Yes should have said, we too have a rope cutter. But when I do have to replace it I still think a folder would be the way to go.

 

[BlueChip]

I have had three bladed folding props on two boats from new during the past 10 years
Nothing but praise for them, one was Volvo the other a CJR. They are both a very similar design with nothing to go wrong, they do the job well and we are never short of thrust astern or forward. I can see absolutely no reason to pay double for a feathering prop.

 

[TiggerToo]

[ QUOTE ]
I can see absolutely no reason to pay double for a feathering prop.

[/ QUOTE ]

if you are happy, great. But why double? Last time I looked, the Kiwis were more like half! /forums/images/graemlins/cool.gif

 

[sailorman]

Go Max
as in MaxProp /forums/images/graemlins/grin.gif
no drag + superb forward Propulsion & even better astern control /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
folding is a completely different concept to feathering /forums/images/graemlins/wink.gif

 

[Habebty]

[ QUOTE ]
mmm I cant see how a rope or in fact anything could foul a folder prop, folded, what could it catch on?



[/ QUOTE ]

My two blade folding prop manged to catch a damn great sheet of polythene whilst motoring into Ipswich Lock this summer. Was towed in by a very nice chap on a Fairline. Tried everything to get the polythene off to no avail. Got the boat lifted and the damn stuff fell off!!!

When I turn the engine off after raising the the sails I put the engine in reverse the prop folds, and I get an extra 0.7-0.9 kt under sail. Definitely worth the drop in motor performance in my book, I just have to think ahead a little bit more when manouevering under power.

 

[thalassa]

There used to be a Radice folding prop on "Alchemist". It was fine on forward, plenty of power. However, due to restricted space and the wheel effect to port, on an incoming tide (drying harbour) I have to reverse out of the row of berths. Combined with a NW wind, the lack of power in reverse did make this absolutely impossible.
We also have to work the locks often here in Zeeland; if you are in a lock next to a giant barge with its props running, maneuvering is very much a hit-and-miss affair.

 

[boatmike]

Lots of posts but no one answered your question! Folding props are a lot less efficient than feathering props. A Brunton Autoprop (IMHO the best) may be expensive but adjusts its pitch to make it easily as efficient, and in many cases more efficient, than a fixed prop. As an example, I have a 10hp wing engine in my boat in addition to the main. With a volvo folding prop it would only manage 3-4 knots at best. With a Brunton I get 6.

 

[Sans Bateau]

[ QUOTE ]
My two blade folding prop manged to catch a damn great sheet of polythene whilst motoring into Ipswich Lock

[/ QUOTE ]

Any prop in use is vulnerable to this. I was refering to a folding prop whilst sailing, folded out of the way. By contrast a feathering prop alwas has 3 blades sticking out, albeit feathered.

 

[Sailfree]

[ QUOTE ]

Any prop in use is vulnerable to this. I was refering to a folding prop whilst sailing, folded out of the way. By contrast a feathering prop alwas has 3 blades sticking out, albeit feathered.

[/ QUOTE ]

Correction 1. often saildrives catch more things and the folding prop cant even open where with feathering or fixed it works and turns with reduced efficiency and enables the rope cutter to have a go at also working.

Correction 2. Feathering props can be 2 or 3 blades to suit the power of the engine. Variprop supplies a 4 bladed one that enables a smaller diameter prop to give the equivalent thrust (less vibration and less chance of catching ropes etc)

All said and done - if my boat was for personal use only I would go for a folding (any make other than a Volvo - losses anodes and had mine replaced 3 times under warantee)! if for use in the Med (much motor sailing) I would go for a Bruntons variable pitch prop. But for a charter boat and shall I put it a prop for all seasons (circumstances) I believe a Variprop is best.

 

[Sans Bateau]

[ QUOTE ]
Correction 1. often saildrives catch more things and the folding prop cant even open where with feathering or fixed it works and turns with reduced efficiency and enables the rope cutter to have a go at also working.

[/ QUOTE ]

Yes agree that saildrives can catch more rubbish. Not sure I agree with the other bit. If the prop isn't open there is less to stop its rotation, thus allowing the rope cutter to work.

"correction 2", yes thanks I was aware of that, just used 3 blade for the sake of simplicity.

So, tell me why would you opt for a folder if it were only for your own use?

 

[Sailfree]

For my own use I would opt for a folder as ideally I like to maximise time sailed and hence least resistance of prop is good.

While feathering have litte resistance a folding has practically nil resistance when sailing and IMHO least chance of picking up debris ropes etc.

I accept power astern is now improved on latter designs but still fairly poor but I hope never to cock up a berthing - some chance!! /forums/images/graemlins/grin.gif

 

[Sans Bateau]

We have the same song sheet Roger!

 

[fireball]

Do you want to try singing in the same key then ? /forums/images/graemlins/grin.gif

 

[Sans Bateau]

"in key", wot'dya mean?