Sailing yacht props

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Catalina36

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Fixed blade v Autoprop v Varifold v Flexofold v Featherstream v Kiwi v Other?

What are the advantages and drawbacks of each? I went from fixed to Kiwi to Featherstream but I've often wondered if I should have gone Flexofold...but then there are others too. Suggestions please?
 
Why? Are you unhappy with the Fetherstream? I have one and am very happy with it. Friends of our have a folding prop and had trouble with fouling that stopped it opening fully so had virtually no power. I have had my featherstream give no drive once when the blades happened to be set at zero pitch in forward but you just operate it in the opposite direction so it comes out of that.

Catalina36 said:
Fixed blade v Autoprop v Varifold v Flexofold v Featherstream v Kiwi v Other?

What are the advantages and drawbacks of each? I went from fixed to Kiwi to Featherstream but I've often wondered if I should have gone Flexofold...but then there are others too. Suggestions please?
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neilf39 said:
Why? Are you unhappy with the Fetherstream? I have one and am very happy with it. Friends of our have a folding prop and had trouble with fouling that stopped it opening fully so had virtually no power. I have had my featherstream give no drive once when the blades happened to be set at zero pitch in forward but you just operate it in the opposite direction so it comes out of that.
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No, I've been happy with it though I'm not a fan of the completely flat blades which seem a bit of a cheap cop-out. Although the pitch is set such that the engine reaches just under max revs, there doesn't seem to be much bite when going from astern to ahead or vice versa. I wondered whether the shaped blades of a Flexofold would give more thrust. Interesting to hear that they can have their problems though, that's just the sort of experience I'm looking for.
 
My boat came with a 3-blade fixed prop on saildrive as new so, after researching the options I changed it immediately for a flex o fold. I remove it each year at haul-out and refit it in the spring (albeit currently hibernating in my garage ?). It’s a very well engineered product and gives excellent performance ahead, astern and in neutral/when sailing. Not cheap but I’d buy another if the need arose.
 
Lightwave395 said:
I have a Maxprop, works a treat forwards and backwards and the pitch is adjustable, unless you only ever motorsail I can't see why anyone would have a fixed prop on a sail boat...
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I have the same. The Maxprop is the original feathering propeller, but its still one of the best.

Despite the above I really can't see why anyone would want to change a Featherstream unless there is something wrong with it, because any other feathering prop is unlikely to be significantly better, and I can't see that a folding prop will be better that a feathering design. Even if a folder has less resistance when sailing it may be less effective motoring.
 
Having previously had a Gori and now 3 seasons with a 3 baded J Prop: I can prefer the latter. Simple to service, easy to alter pitch and plenty of thrust fwd and reverse. Can't comment on price as it was fitted by manufacturer from new.
 
Norman_E said:
I have the same. The Maxprop is the original feathering propeller, but its still one of the best.

Despite the above I really can't see why anyone would want to change a Featherstream unless there is something wrong with it, because any other feathering prop is unlikely to be significantly better, and I can't see that a folding prop will be better that a feathering design. Even if a folder has less resistance when sailing it may be less effective motoring.
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Thanks Norman, that's exactly the sort of experience I'm looking for. I originally chose a Featherstream over a folding prop as I was unsure about the power in astern but if Featherstream is as good as they come I'll be happy to stick with it. It'll save me a lot!
 
They all work if properly fitted. Some work better than others in certain conditions and some suit some boats better than others. I have a Volvo 2-bladed folder which came with the boat when new 20 yrs ago. I retrospect, I might have done better with the 3-blader, but it has served us well even if newer models might be marginally better. I don't regard performance in astern as critical since I usually spend more time going ahead.
 
Hard question to answer unless you compare. There was a very good review comparing them a few years ago but Volvo failed to supply their folder for it. FWIW we have a Volvo 3 blade folder on a d2-40 in a moody 36 weighing about 8 tons. Very happy with it. Noticeable fall off in performance as season progresses and chalk builds up on it. top speed drops as do max revs. Good bite in reverse as well as forward. Big upside is ease of maintenance. One bolt to get it off then an allen bolt for each blade. Knock the pivot pin out for each. Drop the lot in brick acid, rinse, do whatever antifoul you like, grease the spline and back on with a new locking tab washer. No bearings, no adjustment.
 
A few things to consider. I like to quantify things.

The benefits of folders and feathering props are most relevant and noticeable at lower speeds, below a relative speed of 0.9.

The maximum efficiency for a prop in a "good" displacement hull is about 60% That is for a fixed 3 blade. All others, with the possible exception of a variable pitch (overall), are less efficient.

The loss of speed for various props at a relative speed of 0.9 (in my case with a 28.2' waterline, 4.77kts.)

Fixed 3 blade - 0.8 kts
Fixed 3 blade left to spin freely - 0.4 kts
Feathering prop - 0.2kts
Folding prop about - 0.1kts

Many traditional designs don't have the room to swing a folder; I don't.
If your gearbox can be left to spin ( my PRM can), you can reduce the drag by half.
My max gain would be 0.2kts with a feathering prop.

Hmm ...
 
johnalison said:
........................... I don't regard performance in astern as critical since I usually spend more time going ahead.
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If you sail in the Med where you moor stern to, then the ability of the prop to get you going astern from a standstill so that you can back into a space with enough way on to be able to steer becomes vital.
 
I’ve got a Brunton Autoprop fitted to my Bavaria 38. It makes two differences to two things.
Firstly, when compared to the normal Volvo prop, the motor runs at 1800 rpm instead of 2200 rpm for a boat speed of about 5.5 knots.
Secondly, I get slightly I proved performance under sail than with the Volvo standard prop.
However, it’s an expensive beast and I doubt I’d have bothered with getting one if it hadn’t been fitted to the boat when I bought it!
It also needs greasing every year and it usually uses an anode every season or two.
 
I know tht this has all been covered before, my direct experience.
Volvo three blade, several Volvo 2 blades and currently Flexofold thee blade. The three blades do help motoring perfomance considerably perhaps a knot or 17.5% differrence in speed. The Volvo looks sophisticated and does well but the small collar anodes struggle to last a year and are only available in zinc or magnesium. The Flexofold seems to perform just as well and is available with a bigger cone hub anode which is available in aluminium as well as the other two metals, I hope to get 2 years out of the current aluminium anode but I have started painting the prop to ensure this. Darglow are knowledgeable and easy to deal with but insist on using a very expensive carrier for deliveries to Scotland which just about doubles the cost of an anode.
I have had a couple of folders rebuilt when they got floppy, with enlarged pins etc. not too difficult a job for a good workshop but you have to be careful that they use the right metals for everything.
 
Norman_E said:
If you sail in the Med where you moor stern to, then the ability of the prop to get you going astern from a standstill so that you can back into a space with enough way on to be able to steer becomes vital.
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Ditto for Holland and Northern Europe without the steadying effect (I found) of the bow anchor in a Med situation.
In Scandinavian countries they like to go bow first, but our bow is some 2m high and the missus not a member of the alpine team, so again, stern to.
Trying to maintain position in high winds in the narrow confines of a canal, while waiting for a lock or bridge to open quickly demonstrates the desirability of some degree of reverse function and maneuverability.
I know a Dutch gentleman who kept two props on hand for his boat, depending on the main cruising area he had in mind. A Brunton for open water, ( he said it was not so good for maneuvering) and a Max prop for inshore work involving close maneuvering, canals and locks.
 
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