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Folding vs Feathering Prop - views requested

16K views 58 replies 26 participants last post by  dantaden 
#1 ·
I am looking for your views, pros/cons, experiences and recommendations for selecting a type and model of prop.

My Celestial 48' is powered by a 72hp Merecedes Diesel with a fixed 3 blade 18" 18RH12 prop.

I am considering changeing this to either a folding or feathering prop -leaning more towards Gori's 3 blade at this point.

It would be much appreciated as well if you could include your sales and service experience with the dealer who sold you the prop.

Thanks and look forward to views.
 
#3 ·
Why are you looking at a prop change? Are you racing and want to get maximum performance or are you cruising and want a good compromise of sailing and powering?

For all out racing, a folding prop is best generally. However, the propeller will not do a very good job trying to power into rough weather and will make the boat hard to control in reverse. The units do also have wear parts which means they will need rebuilding from time to time.

For cruising, a compromise prop would be a feathering one. They have significantly less drag than a conventional fixed blade unit but still provide good motoring performance. One drawback that I have run into is that they cost a lot and need to be rebuilt from time to time. The max props seem to hold up for a while before needing rebuilding but my experience with a luke prop was that it needed rebuilding quite often. The luke wheel is not a common unit but it did actually fail a couple of times (it is a 32X20 so the smaller ones might be better). These feathering units also have the tendency to hook on lines so if you sail in places like Maine, you have to be careful.

Another option if you are looking for improved cruising performance is the campbell sailor. I have no experience with this propeller but it gets good reviews and may fit your circumstances well.
 
#4 ·
I'll also vouch for the Max Prop; you should be able to find a lot of information on it and the Auto Prop by searching older posts here at Sailnet (I find doing a Google search with " site:www.sailnet.com/forums" appended works well --- eg. http://www.sailnet.com/forums/gear-maintenance/51249-maxprop-autoprop.html ).

One thing I like about the Max Prop is that it's quite effective when backing the boat out of the slip (its blades reverse direction so it has a good bite on the water) and has significantly reduced prop walk compared to the same boat with fixed 2 or 3 blade props. This can be very helpful if there's a good crosswind at your slip or for other tricky situations. I've read that folding props are poor in this regard.
 
#8 ·
Thanks for your experience. I'd like to keep discussion open for more advise on these and other models.

Autostream - first I have never heard of these guys but there product looks interesting. The folding props looks very similar to Gori's. What was your experinece dealing these guys during the sale and delivery and have you experience there service yet - is it global.

Autoprop - always been curious about this prop. Can you advise your experience with fwd/reverse prop walk and if you found the blades move and noisey under sail. As well, any trouble with blades not opening under fwd/rev. And as above your sales & service experience, how was it ?

Please forgive the interogating questions, but I'm a little more cautious with this than normal boat stuff since it is far more costly to change a second time.

Can you advise if the your new prop was sized right the first time ?

Thanks for your comments and I look forward to more.
 
#11 ·
Thanks for your experience. I'd like to keep discussion open for more advise on these and other models.

Autoprop - always been curious about this prop. Can you advise your experience with fwd/reverse prop walk and if you found the blades move and noisey under sail. As well, any trouble with blades not opening under fwd/rev. And as above your sales & service experience, how was it ?
Very little prop walk, the efficiency is the same, backwards or forward, you don't hear nothing and no problem at all. I had never need any exterior service. the maintenance is very simple and I have done it myself (5 minutes).

This is not just a folding propeller, but an automatically adjustable pinch propeller. It´s biggest advantage it's the cut on fuel consumption and the increased autonomy.

It is especially efficient while motorsailing. Suppose I have wind to make 3.5 knots and I want to make 6 knots. With the standard propeller I would have to put the motor at 2000rpm. With an Autoprop, to do the same, I only need 1000rpm. There is almost no noise and the autonomy increases almost twice, not to mention costs and motor life. The only problem is that when the wind picks up and you don't need that extra push to sail at more than 6K, sometimes you forget to turn the engine of, because you cannot hear it.

It is also very efficient if you have flat seas, or just small waves. In those conditions I could make the same speed with less 800rpm, comparing with the standard propeller.

Minus:

Price

In stormy or very agitated seas probably this propeller is marginaly less efficient than the standard one. On those rare conditions were the speed of the boat varies constantly because big waves are stooping the boat I believe that there is some loss in efficiency (because the pinch is changing all the time), but I am not sure.

The other only propeller I would consider to replace an Autoprop would be a Gori with and overdrive. They were also impressive on that test that I had mentioned.

Regards

Paulo
 
#9 ·
I bought my Autostream prop directly from the USA distributor, which is Martec. Gary, who I believe is the son of the original Martec designer, spent about two hours going over both the Martec folding and the Autosteam feathering. Customer service was outstanding.

Autostream is made to order in Australia by Skyhawk Ltd. They have a really good website which goes over their product. I like mine.
 
#10 ·
I have had good experience with Maxprop. I had a two blade design on my previous boat and have a three bladed for my current boat. In both cases the boat is was easy to control in reverse while giving good performance overall. The folding props, as someone mentioned earlier, are really only of interest to racers.
 
#12 ·
VariProp

Got a Variprop for my CS34 last year to improve the sailing performance and help with a little local racing. I have been very impressed with this prop.

Pros:
  1. Easy to install
  2. Very easy to adjust pitch, both forward and reverse
  3. Excellent power in reverse, better than my old 2-blade fixed with less propwalk
  4. Good power through rough seas (3-blade model)
Cons:
  1. Expensive (consistent with other feathering props)
  2. Defective screws detected by manufacturer, but they changed out the entire prop-head for a new one at no cost - even offered to pay the haul-out fee
  3. Not quite as efficient as a fixed prop
I went with feathering over folding because I have to reverse our of a slip in a narrow channel. Folding definitely has lower drag, but not as much thrust effeciency.
 
#15 ·
Most of the feathering props are 'pitch adjustable' .... some can either have their pitch adjusted while the prop is still installed and the boat is IN the water. With most feathering props, you can OPTIMIZE the prop's pitch to optimized engine rpm for best power/efficiency,etc.

Folders while having much better drag characteristics, cant be easily pitch adjusted.
 
#18 ·
Most of the feathering props are 'pitch adjustable' .... some can either have their pitch adjusted while the prop is still installed and the boat is IN the water. With most feathering props, you can OPTIMIZE the prop's pitch to optimized engine rpm for best power/efficiency,etc.

Folders while having much better drag characteristics, cant be easily pitch adjusted.
This is precisely why I chose a four-blade feathering VariProp for the steel cruiser (I want a far more torque-y bite in reverse) and a Gori folder for the racer.

I have yet to install the VariProp as I am repowering this year, but the Gori's been on a number of seasons and you can read my positive remarks (and a few reservations) using "Valiente" and "Gori" in the search function.
 
#16 ·
We had an Autoprop on our Northsea 34 for 15 years and never had a problem with it. No prop walk and lot's of thrust in forward and reverse made close quarters maneuvers easy. You do need to use more throttle from a stop compared to a fixed blade, but you get used to it. Our sailing speed in light winds increased at least 1/2 knot compared to the three blade fixed and our motoring speed increased almost 3/4 knot at the same rpm so we reduced the rpm to cut down on engine noise and still maintained a higher speed. The only contact with the dealer was to order the little zincs, which we received promptly. Wish I could afford one for the current boat.
 
#20 ·
Had an Autoprop on a 36'er and loved it. The pitch was perfect from the beginning but the boat did prop walk something terrible but I'm not sure if it was the boat or the prop. I got used to it and used to my advantage when approaching or leaving docks. Picked up apx 3/4 kt of speed under sail alone and suspect an equal amount under power. Always drove the boat consistently strong. The worst conditions were 30kts on the nose, 5-6' chop for 6hrs and never a problem. You do need to make sure you grease the hubs when you haul the boat for painting, etc. Otherwise a blade can hang up and cause vibration at low speeds. The only real issue was longevity. Seems the prop we had experienced some corrosion to some internal portion of the bearing race. As it was not a replaceable part it's expected that prop at some time will have to be replaced. Not sure if this was an issue with this particular prop or not. Traded the boat so will never know.
 
#22 ·
Thanks again everyone for your comments.

I have read on other threads that most featuring props require periodical maintenance, Variprop, Maxprop etc.. I have also heard the same with Autoprop, but requireing annual maintenance (bearing replacement) and overhaul. Some owners had experienced losing Autoprop blades.

and other owners have experienced no or very little problems or maintenance with their feathering or Autoprop.

I suspect these are extreme cases and/or perhaps some impact from salt water.

Is the above a valid concern - can anyone share further experiences ???
 
#23 ·
Dan - Your summary seems about right from the reading I've done as well. One other item I can add about the MaxProp . . .

The MaxProp on my boat was corroded because the zinc was allowed to be completely consumed. In addition, the prop was a little oversized for the boat and was not allowing the engine to reach its proper full RPM (this was observed in the survey when I purchased the boat). Adjusting the pitch was not sufficient to overcome the problem in my case. The prop was sent back to PYI for refurbishing, and they were able to reduce the prop diameter, polish it back to like-new condition, lube it, etc.. PYI was very knowledgeable about the use of their product in a wide range of circumstances, and was very customer focused. It was nice experiencing such competent and truly helpful support from the vendor.

Here are the before - after pic's . . .
 

Attachments

#24 ·
Dan - Your summary seems about right from the reading I've done as well. One other item I can add about the MaxProp . . . .
MC - can you expand on the annual maintenance required on the Max if you've had it long enough?

I have an opportunity for a pretty good deal on a used Max - so I'm curious as to what's involved on an on-going basis...
 
#25 ·
Faster - From reading other threads, I believe annual maintenance may be required for the AutoProp. Regarding MaxProp maintenance, re-lubing is recommend every 2 years, as per the following from the PYI web site . . .

PROPELLER MAINTENANCE
The Max-prop needs to be degreased a minimum of once every two years. We recommend Lubraplate “130 AA” grease.

There are two holes in the spinner of the propeller to grease. Remove the set screw from the forward holes with a #3 metric Allen wrench and screw in the zerc tower, attach your grease gun and fill the propeller with grease until the grease starts to come out between the hub (1) and the spinner (7). Replace the set screw and remove the set screw from the more aft hole. Reinstall the zerc tower and attach your grease gun and fill the propeller with grease until the grease starts to come out between the blades and the spinners. Remove the zerc tower and reinsert the set screw into the propeller. Do not leave the zerc tower in the propeller.
• With each pump of the grease gun rotate the propeller from forward to reverse to allow the grease to work through the propeller.
• The numbers above are from Figure 2 at the beginning of this Max-prop Manual
• Make sure that you always keep the zinc anodes in good condition. They must be replaced at least once a year. The propeller must be protected by a lot of zinc, so also use a zinc on the shaft when possible. When replacing it make sure that you clean the contact point between the zinc and propeller. Use a wire brush or fine sandpaper to clean the aft of the end cap and the forward face of the zinc to give the zinc good contact with the propeller.
 
#26 ·
Thanks for that... had found it myself just this morning and have printed it. Seems straightforward enough.

I take it you've not done this yourself yet.
 
#27 ·
Correct, I'll be doing it myself for the first time this coming spring. I'm wondering if the recommended grease (Lubraplate 130 AA) is available generally (e.g., at WM), since they make a point of stating not to use Teflon grease as it will wash out easily.
 
#28 ·
Let's hope so.. esp since one of the reasons for recommending it was lower cost!:)
 
#29 ·
I installed a Flexofold on my 40' Beneteau Oceanis 2 months ago. Since then we have sailed 300 miles with the new prop.

I ordered straight from the US distributor here:
Flexofold Low Drag Folding Sailboat Propellers for Racers and Cruisers

Beautiful prop (I had it on my desk for a few weeks at work before the install!).

Performance wise there is a .5 to .6 knot difference between it folded and not folded. If I am sailing VERY slowly and I slowly motor down to neutral I can trick the prop into "windmilling" like my fixed prop used to with the sails driving the boat. I can be sailing 2.5 knots in light wind and hear it turning (if I managed to motor down correctly). Once I go down and grab the prop shaft and slow it slightly you can hear the blades fold and the boat accelerates .5 to .6 knots. I have done this a few times to verify the results and to prove the difference to friends.

Motoring is more efficient (same hull speed with 300-400 RPM less engine speed) and backing is identical to my old fixed prop.

Customer service was excellent.

The anode covers the working parts and pieces thereby reducing the likely hood of the prop being fixed by marine life.

Hope this helps.

Brian-
 
#30 ·
I too noticed such an improvement in sailing qualities with my Gori folder in terms of acceleration in a puff that I had to revise at what apparent wind speeds I would change my sails (I have hank ons).

Basically, I got the better part of a knot for "free" and while I haven't noticed much change in "top speeds" for a given sail area, set and similar apparent wind speed, I get there quicker and the whole motion of the boat is "sprightlier" if that makes sense.

I can't necessarily attribute this to the folder, but my hull speed is, in theory, 6.9 knots on a 26 foot LWL. My GPS in current-free water once recorded 7.3kn on a close reach on a day with 25 knots, a No. 3 and a single reef set. Last Sept. 28th, with 25-28 knots, a No. 3 and a full main set, we hit 8.9 knots SOG on a beam to broad reach. I've never surfed for so long in this boat, and while I can't credit having a folding prop, my gut says that taking that resistance out of the equation allowed us to get surfing sooner.
 
#31 ·
As most think folding props are designed for racers - this is not necessarily true. Now, with more cruising in mind, I see the benefit of a folder, getting to destination quicker under sail, leaving less mileage for motoring.

Valiente, just curious why you decided on a 4 blade feathering and not a 3 or 4 blade folder ?

Back from the Toronto boat show and still the Gori 3 blade folder w/overdrive is top of mind for my 48' Celestial (34,000lbs).

Please advise and share comments.
 
#41 ·
Valiente, just curious why you decided on a 4 blade feathering and not a 3 or 4 blade folder ?
My boat's a steel motorsailer with a full keel, and I am going to a slightly larger engine (from 52 to 60 HP). The full keel "blankets" the stern somewhat in a way a cutlass bearing aft of a fin keel does not. My shaft angle is near zero degrees.

When I shut off the engine, the four blades will feather to a very small frontal area, and I can rotate the prop shaft to "top center up" to orient the blades for the most minimal of drags. Seems fussy, perhaps, but we are going well offshore and every mile made good will be in part about reducing drag.

The VariProp will allow different pitches in forward and reverse, and I want a relatively shallow pitch for forward that matches the new engine's power curve for economy. In reverse, I want full-on torque for stopping and maneuvering ability. This meant, perhaps ironically, that I wanted a lot of prop blade area for low speeds.

I'll let you know how it all turns out...;)
 
#32 ·
Folders

Many previous designs of folders allowed marine life to foul the working of the simple (and fairly open) folder. This meant that they were only really a viable choice for guys who were very maintenance conscious or didn't keep their boat in the water (like racers).

The Flexofold's design significantly reduces that likelihood (as does many of the newer other brands).

I bought the folder because of the lack of maintenance required, greater reduction in drag and the great reviews it had been given along with some very good customer service.

The benefit had been our ability to sail when previously I would have motored. The Puget Sound had very weak winds in the summer months.

Brian-
 
#33 · (Edited)
I believe that the Gori with overdrive and the Autoprop have some advantages over the others in what concerns cruising...if their prices are not a problem.

I failed to mention an useful feature on the Autoprop propeller. If you see a rope too late to stop or change direction and run over it, if you have time to shift to neutral, probably you don't get stuck (the blades move freely and avoid getting caught). It seems a small thing, but saved my day at least three times in the last 5 years.;)
 
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