Folding/Feathering Props

[Gerry]

What has been the group's experience with feathering/folding props?  What props have you tried (with which engine)?  2 bladed or 3 bladed? Feathering or folding?  Brand? What did it do to performance: sailing? motoring? reversing?  Meet/exceed/or fall short of expectations?  Anyone have a folding/feathering 3 blade for Universal M35 for sale?

[Randy Stolze]

Gerry,

       If you do a search on this board for propellers you will get a whole lot of information on different props. I recently purchased a Flex-o-Fold after doing the kind of research that you are beginning. I am very pleased with the performance picking up a knot of motoring speed. Sailing differential is supposed to be at least half a knot better. Backing power seems to be equivalent to the fixed three blade I replaced. Cost was about 1300.
       Used folding props are like hens teeth. I stumbled across this listing recently that looks pretty good if it is a three blade prop.

  AUTO PROP for 36' Catalina. Like new. $750.00 1" Shaft Call Bill at 270-362-8364, Ext. 36 or weg@greenturtlebay.com

Contact Phone:270-362-8364

  Happy hunting

  Randy

[John Langford]

Randy, from your note I am assuming you went for the 3 blade Flex-o-fold. Can you recall the configuration (diameter and pitch) that you installed? My guess is that you have an Universal 25 rather than 35 at the other end so the configuration you used might not work for my 35 and it particular gear box. I tried to raise Flex-o-fold through their website with no results and I have yet to find a local distributor. I would appreciate any other information that list members might have on this prop. It looks good on paper.

[sail4dale]

Just purchased a flexofold and having it installed now.  Was able to get fine dialog with them at this address:

Chuck Angle" <amsales@flexofold.com

[Randy Stolze]

John,

   I have the three blade 15 x 10 pitch. The only distributer that I am aware of is in Marblehead, Mass.

   You could be right about your engine requiring a different pitch. The person you want to talk with is Chuck Angle of Flex-O-Fold(787-631-3190). Tell him you are a member of the C34IA and ask for the "show price". It's worth a try, mabe you can save a few bucks.

   Good Luck

   Randy

[Steve S.]

John, Gerry:

I have the 25 in my 88 Catalina and the 3-blade, right handed, 15 x 9 with one inch shaft was recommended.    As Randy said, call Chuck in Marblehead.  Very nice guy.  One thing you will note with the flexofold is how much bigger and heavier than the old 3 blade prop.  Therefore it is critical that you have the minimum amount of space between the prop hub and the strut.  There are varying opinions.  I've seen tolerance should be no more than 50% greater than the diameter of the shaft (1" 1/2) and I've seen no more than 50% of the shaft (1/2").  To play it safe, I removed my drivesaver this weekend and got it down to 1/2 ".  

Steve

[jwlittle]

 Fellows,
   I recently installed a Gori 3 bladed prop on my '88 C34.  I gained a knot of sailing speed but lost half a knot motoring.  I checked with a prop shop and a university professor with engineering programs on props.  Both said the 15x9 was way under pitched. I tried for months to get A-B Marine to send me the correct blades.  I found the company completely unresponsive to my needs and arrogant in their defense of their mistake.  I offer this only as a warning to my fellow C34 owners: Buyers Beware.

[Ron Hill]

jw: Interesting about the Gori "Customer Service"!!
If you'd looked in the Mainsheet and in this site you would have found that most of us have up-pitched our 3 bladed Sailor fixed props to 15X10.   

[steve stoneback]

I have a 3 bladed Maxi-prop.  It was on the boat when we bought her so I don't know how much it improved the sailing performance.  The pitch can be set which is nice.    When I got the boat the engine wouldn't get enough rpm so I changed it to increase the rpm to 2,700 at 6 knots.  When docking in a stiff wind the prop works great in reverse but it has quite a bit of port prop walk. All in all I am pleased with it.
steve

[Marshall Tonner]

I have a 15x12  2 blade Vari Prop. Sailing speed has increased by about a knot at top end, prop walk has been elliminated , but I gave up a lot when powering into wind and waves.I should have spent the extra and bought a 3 blade.

[clifford Rieders]

I have had the 3 blade flex-o-fold for some years. great product but be prepared to replace your Cutlass Bearing much more often. the weight of the prop will eat away the thin rubber in that bearing rather quickly. Luckily a toolmaker friend of mine with help from Dave Essig at Catalina (now gone unfortunately) made me a cutlass bearing tool remover that works great.

[Ron Hill]

Guys : As Cliff mentioned "the weight of the ... prop will eat away the thin rubber ... be prepared to replace your cuttless bearing more often". 
This is the nature of a feathering/folding prop, because a larger/heavier hub is necessary to accommodate the feathering/folding mechanism !!!   

[Mark G]

Guys, I know this is a well worn topic with lots of previous info. Still, it's always interesting. But how fast are you going when you say you gained a knot or a half knot? My '91 with a wing keel and the M35 with a 3-blade fixed prop motors at 6.4 to 6.6 on the GPS with an end-of-summer bottom with ablative paint. A little faster in the spring. A little slower into a headwind or waves. Tach reads just under 2,100, which is probably wrong but works out to right around 75% of the max.

[Mike Vaccaro]

There's another prop that doesn't weigh any more than the stock prop, feathers without gearing and is mostly composite.  It's called a "kiwi feathering prop."  We recently installed one during haul-out. 

We don't have full data; but noticed that we hit cruising speed (5 knots) at 200-300 rpm lower than we did with the standard Michigan Wheel 15 x 9 three-blade that we replaced.  With the prop set at 19 degrees of pitch, we found that there is about a .7 knot improvement at full-throttle.  Overall, we estimate about a 1/2 knot improvement under power in forward (about a 10% improvement)--imagine this would be similar to a three-blade fixed prop that had been re-pitched to 10 or 11 inches. 

The "wow" improvements occur in reverse and under sail.   Prop walk is greatly reduced since the blades on the kiwi prop rotate nearly 180 degrees to provide reverse thrust.  They rotate to a setting of 23 degrees, which loads the engine a bit and is not optimized but an average setting for engines less than 50 HP, but the amount of prop walk is noticeably reduced and stopping performance is improved over the stock, fixed prop.

Under sail, the most noticeable difference is in light air--with the prop feathered, a large chute, we ran at nearly true wind speed which is an improvement of about a knot.  With just the 100% working jib under the same conditions, we noticed about a 1/2 knot improvement.  At low speeds, this equates to a 10-25% improvement, depending on sail configuration.  To feather the prop, you reduce power to idle, shift to neutral and shut down the engine.   

We chose the Kiwi since it's a dirt simple design--not without moving parts, but far less complex than other all metal feathering propellers.  It's inertial characteristics are almost identical to the Michigan Wheel prop it replaced.  Pitch is simple to adjust, if required, and may be done under water.  It is pitched and pre-greased at the factory, and does require grease at 2-3 year intervals.  The composite blades are easy to replace, but there has been no documented case of blade failure thus far.  The newer versions utilize a 316 stainless hub vs. the bronze of older versions--making the prop more electrically compatable with AQ19 or 22 stainless running gear.

The prop is priced at about half of a traditional metal feathering propeller at $1250 and is only available in a three-blade configuration.  The price included express shipping.  The manufacturer has a questionnaire that allows them to properly configure the prop.  The 19 degree pitch in forward is optimized for our 23-hp M-25 XPA.  We ordered the prop from the North American distributer, West by North Enterprises in British Columbia.  It was custom-built and drop shipped directly to our house and arrived six days after we placed the order.  The company has built numerous props for Catalina 34's and 36's with the M-25, so sizing wasn't difficult.  Kiwi props also maintains a website with the sizing questionnaire and other information about the propeller.       

Installation is very simple, only 20 minutes required (although this was simplified by the fact that we also installed a new shaft, so it wasn't necessary to clean the old one).   

Our experience is limited to the 4-hour shakedown returning from the yard; so this is just a preliminary assessment.  We did notice a distinct sound as the blades transition from forward to reverse (and vice versa)--also we are still looking at vibration patterns.  We had managed to eliminate all vibration (except at idle RPM) with our old prop and the goal is to do the same with this one.  Don't know if the transitional stress on the transmission is increased or not. 

In the spectrum of propellers, this prop would fit between a properly pitched Campbell Sailor fixed three-blade and more expensive feathering type like an Auto-prop or Max-prop.  Gains are improved light-air sailing performance, better handling under power in reverse, reduced prop drag during sailing.  Downside is increased complexity, i.e., odds something may malfunction, and cost.  Opinion:  appears to be a great "middle ground" option for an overall 10-15% increase in performance without some of the disadvantages of more complex props (cost, weight and maintenance).     

Will post a follow-up as we gain experience and I have a chance to ask the folks at Kiwi Propellers some questions.

Cheers,

Mike

[Jon Arck - Past C34IA Commodore]

Hi, Everyone

If you're interested in a Flex-o-Fold, check the Ship's Store, as they advertise with us and give C34 members a year-round Boat Show discounted price.

We're considering a three-bladed F-o-F.

Good luck and good sailing,
Jon