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Old 28-05-2016, 11:43   #1
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Feathering vs Folding Prop

Hello,

My girlfriend and I are refurbishing a Santana 37 for cruising and wanted to get some advice on feathering vs folding props.

The boat currently has a two-bladed folding prop which doesn't work too well in reverse. On the flip side, we are concerned about drag as we want to boat to sail as well as it possibly can.

Any insights from people who have considered switching?
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Old 28-05-2016, 11:58   #2
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Re: Feathering vs Folding Prop

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Originally Posted by sailscubasurf View Post
Hello,

My girlfriend and I are refurbishing a Santana 37 for cruising and wanted to get some advice on feathering vs folding props.

The boat currently has a two-bladed folding prop which doesn't work too well in reverse. On the flip side, we are concerned about drag as we want to boat to sail as well as it possibly can.

Any insights from people who have considered switching?
Her us a link to many previous discussions in this forum on the topic of "feathering props."

Many comments, tips, and opinions.

Good luck on your choice.

https://cse.google.com/cse?cx=011403...rop&gsc.page=1
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Old 28-05-2016, 12:43   #3
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Re: Feathering vs Folding Prop

Sailing-wise a folding one is just like a feathering one. And, as you noted, the folding ones often lack kick in reverse.

Folding and feathering propeller test

I would keep the folding thing if your only consideration is your sailing performance.

I normally do not motor sailing boats in reverse for any extended length of time ...

b.
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Old 28-05-2016, 14:19   #4
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Re: Feathering vs Folding Prop

Feathering props will have more thrust in reverse but less thrust in forward compared to props like Flexofold. I wouldn't sweat it too much, if you have a folder that works ok think of other places to spend your hard earned money.
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Old 28-05-2016, 14:59   #5
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Re: Feathering vs Folding Prop

I have had both Max Props (feathering) and folding (Flexofold). The Max props are pricy, best reverse performance (prop feather 180 degrees in reverse, give you a leading edge in reverse), and you can set the pitch. Flexofolds don't match the Max props in reverse, but are probably superior in forward - and cost less.
You need to make sure you end up with the correct pitch and diameter for the boat (ie, eng/trans), and with a prop that is not pitch adjustable that you can swap blades out until you get the correct combination.
Good luck
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Old 29-05-2016, 08:50   #6
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Re: Feathering vs Folding Prop

I had to replace a Gen 1 Autoprop (3 blade feathering) and chose a 2 blade folder. The feathering prop was roughly the same as the folder in forward, but superior in stopping and reverse....far superior in stopping. It was a simple economic choice between $1K and $4K+. If they had been close in price, I would choose the Autoprop, but they weren't. I just adjust by slowing down a bit when docking.

Good luck with your project.
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Old 29-05-2016, 10:17   #7
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Re: Feathering vs Folding Prop

I have a Gori two-blade folder on the GG sloop I'm selling and a VariProp four-bladed feathering on my steel motorsailer.

So I guess I've seen both sides.

You don't mention your displacement or motor size or prop size and pitch; I assume it's 35 hp diesel or something in that range. Things like how much you use the motor vs. sailing would affect my answer here. I certainly advocate either type for the reduction of drag.

The answer for you would depend on several factors, such as pitch: If the folder is rather flatly pitched in order to meet the power curve of the engine (a rather complex subject) and to give best economy at cruise speeds, you can't really improve that. You may not be aware, however, that some feathering models allow diiffering pitches in forward and reverse, to wit: a flatter pitch in forward and a coarser, more assertive pitch in reverse for effective stopping power. It's not a CPP, but it's a solution for some.

By the way, I dock the folder-prop boat by going dead slow, making a turn into the line of slips in neutral, and barely touching the reverse. A few seconds' worth of time beats the possibility of dinging the bow. You can always add speed, but if you have to redline in reverse, you're probably going too fast. In other words, practise on a clear sea wall until you learn how much "glide in neutral" matches your need to use just a touch of reverse to, say, prop-walk the stern in. I do this all the time with my heavy steel boat. I'm at a dock finger end, so I also let the wind push me in as I "station keep", but my solution may not be necessary for you with some techique.
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Old 29-05-2016, 10:27   #8
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Re: Feathering vs Folding Prop

There are reportedly some decent folding props out now days. Your old Santana likely has one of those terrible folders for racing... useless. I'm a feathering fan. Great performance with zero issues IME.
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Old 29-05-2016, 10:50   #9
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Re: Feathering vs Folding Prop

I don't understand the big deal about reverse

If you have a prop that means stopping distance is longer, learn your boat and understand when you need to start reversing or perhaps give it more revs.

I think it's better to get a prop that allows you to travel forward faster or the same speed with less revs and accelerates better so that when you are motoring into some chop you lose less speed. After all most of us probably motor forward 99.9% of the time and reverse the other 0.01%

I'm happy with my Flexofold 3B as it does all of that.
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Old 29-05-2016, 11:47   #10
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Re: Feathering vs Folding Prop

Hoppy,

Some of the older folding props are all but useless in reverse. A J-35 I race on has one, and maximum sped in reverse is about 1kn, and it takes 30-45 seconds to bring the boat to a halt. In any type of a crosswind it becomes all but impossible to back in so we bow in when we have too. At least here we have enough man power to stop the boat by hand, but on a cruising boat it would be a disaster.

Modern feathering props are better in reverse than a fixed prop, and almost as good in forward. We have the an Autostream and love it.
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Old 29-05-2016, 12:09   #11
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Re: Feathering vs Folding Prop

I raced boat with folding props and never liked them... Don't get me wrong, they do what they are designed to do, decrease drag, but I never understood why you would want give up reverse thrust and prop walk for one.

Also, some Gori Prop owners reported transmission problems, mostly as a result of overly aggressive shifting into the over drive function. Basically, they were shifting into reverse without allowing the prop shaft to spin down. Rookie mistake, but costly replacing the transmission.

On my own C-47, I had a 3 bladed fixed blade prop and converted to a MaxProp VIP about two years before we started cruising.

The change over was easy and I set the prop to the recommended pitch the first time.

The new Max Prop feathering prop matched the old fixed prop for hull speed/RPMs, but I gained a full knot of sailing speed from the fixed blade to the feathering prop. In addition, the prop walk was similar to the fixed blade and the reverse thrust was excellent.

If I had to do it over, especially for cruising, I would still buy a Feathering Prop.
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Old 29-05-2016, 12:15   #12
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Re: Feathering vs Folding Prop

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Hoppy,

Some of the older folding props are all but useless in reverse. A J-35 I race on has one, and maximum sped in reverse is about 1kn, and it takes 30-45 seconds to bring the boat to a halt. In any type of a crosswind it becomes all but impossible to back in so we bow in when we have too. At least here we have enough man power to stop the boat by hand, but on a cruising boat it would be a disaster.

Modern feathering props are better in reverse than a fixed prop, and almost as good in forward. We have the an Autostream and love it.
Ok, I didn't know that some could be that shocking.

My Flexofold has a so so reversing score in the test that was linked to, but whilst it's lowly ranked I certainly have no problems reversing in the marina and into town quays whatever the wind conditions.

I'll qualify my earlier comment to say that when choosing a new prop, any of those in the test will be satisfactory for reversing, so concentrate on the forward performance



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Old 29-05-2016, 12:34   #13
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Re: Feathering vs Folding Prop

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I raced boat with folding props and never liked them... Don't get me wrong, they do what they are designed to do, decrease drag, but I never understood why you would want give up reverse thrust and prop walk for one.
I have plenty of reverse and prop walk with my Flexofold, it's 2nd fastest in the test, maintenance free and cheaper than a lot of the feathering props.


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Old 29-05-2016, 13:07   #14
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Re: Feathering vs Folding Prop

This topic has been thoroughly discussed in another thread, so I will only add a little to this thread (please read what already exists first).

The main reason that feathering props tend to be less efficient than fixed props (and folders) is that the blades are flattened. In the quest for speed under sail (the market is mostly for racers) the drag is kept down by flat blades - twisted blades in the feathered position have a bit more drag. That is a sensible trade-off for racers, but less so for cruisers. The ideal feathering prop for cruisers would have curved blades like a fixed prop, thus losing a tiny bit of speed under sail and picking up motoring performance. As it happens the Luke feathering prop, originally designed about a century ago, does meet this requirement and is significantly more efficient under power than other feathering props. It is a simple and robust design, but lacking in field adjustability. This is what I chose to use with the new engine.

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Old 29-05-2016, 13:56   #15
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Re: Feathering vs Folding Prop

FWIW, I've had 3 boats with folding props, never had any reversing problems and if they are pitched right, no forward drive problems either. Significantly, they don't pick up weed and plastic trash which I can imagine a feathering prop doing.
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