Kiwi Feather Prop

[Steve Sayian]

Just got my Feb '07 issue of Mainsheet yesterday and under the C34 section there was an article about the Kiwi Feathering Prop from West by North Enterprises.
I'm in the market for a 3-blade feathering prop and am wondering if anyone out there has the Kiwi and how it performs.

Steve

[sail4dale]

I have a Flexofold (and love it) but a boat pal has had a Kiwi for three years on his 37ft sloop.  He loves it and it also backs very well.  He does extensive cruising on the California coast.

[Stu Jackson]

Steve, there's been some discussion about props over the years.  Because of the rather unique name, a search on "kiwi" got about 9 hits. FWIW, I agree with the KISS theory, with our 3 bladed prop it's like draggin' a bucket, but with our outboard motor and barbecue hangin' off the rail, and our dodger puttin' up even more wind resistance, I'm happy knowing there's no more moving parts underwater than are basically required.   

[Mike Vaccaro]

Steve,

We've been running a Kiwi prop on our 34 for about six months now.  This is an outstanding prop.  Here's the original post we made:

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. (Haven't done this as of 15 Feb 07!)

Addendum:  The prop has a tremendous amount of thrust in reverse compared to a fixed pitch prop.  The performance of the boat, especially in light air and when tacking is noticably improved.  No issues getting prop to feather properly.  Although max speed isn't increased by more than about 10%, thrust into chop is noticiably better than our old 15 x 9.  We haven't had the prop long enough to have gone through a service cycle, but it will require minor maintenance during the next haul-out.  Incidentally, we had intended to order an extra blade; but after discussion with the folks at Kiwi decided not to when we found that there have been no documented cases of blade failure.  We had the old 15 x 9 refurbished and carry it on-board with a spare key and installation nut as a spare.  We got great service from the folks at West by North (North American dealer).  It was a toss-up between a new fixed Sailor prop or the Kiwi.  No regrets about selecting the Kiwi. 

Please drop a line if you have any specific questions. 

Cheers,

Mike

[John Langford]

I have had a Kiwi prop since last spring and the performance is everything Mike says it is. One small point. I (and a friend who has a Kiwi on a C400) have found that if you shift into neutral and turn off the engine, the prop continues to turn. The Kiwi rep and the manual describes this as "rotating slowly" but I was unable to stop the prop by grabbing the shaft (with a good glove on). It appears that you can stop the rotation by shifting into reverse and then shifting back to neutral. I am assuming that you want to stop the rotation to gain full advantage of the feathering.

[David Sanner]

John, it sounds like when you lock it in gear it feathers and
your good to go but it's suppose to feather in neutral.

You may want to make sure all of your blades are free
to rotate properly.  I was just reading an article about the
Kiwi Prop and apparently the owners did some minor sanding
on one of the blades/mounts to get it to move easier. 

The manual says:
"AUTO ROTATION:
If high speed autorotation occurs when sailing check for freedom of movement of each blade
and the presence of foreign objects – typically fishing lines or pieces of rope, flotsam etc that
has been picked up by the propeller.
Each unit is biased by modifying the last few millimeters of the trailing edge on one side to
provide a slight camber to each blade so that any tendency to auto rotate will always be
against the normal ahead direction. Normal operation will be for the prop to slowly slow down
and then stop.
If it continues to turn slowly, there is no problem putting it into gear to prevent this. The
blades are still feathered. The water flows around the propeller of any yacht are very complex
and turbulent. Lee way and disturbances from the shaft and strut make specific predictions
very difficult. Eliminating rotation will minimise any potential blade movement and thus wear
over time."

[Tom Lanzilli]

At some point I would like to upgrade to a feathering prop, does anyone know of an article that compares the various models available on the market?

[Steve Sayian]

Hi Mike,

Just tried to send you mail about how the Kiwi is doing and what you had for a prop before switching (2 or 3 blade).
The email address in the database bounced when I used it.
If you can send me your email address I'd appreciate it.

Mine is: ssayian@hotmail.com

Thanks,
Steve

[Steve Sayian]

Hi John,

I tried to also send you mail using the address in the Database and it too bounced (same problem I had with Mike).

Wanted to see how the prop did in 2-3 foot head seas and what you were running before you switched (2/3 blade).

Can you send your email address to: ssayian@hotmail.com please?
Thanks,
Steve

[Steve Sayian]

Hi John and Mike,

Ordered the Kiwi prop last Monday and it came yesterday.

Snazzy looking and the following edges on the blades are quite sharp! (liked the free hat they included)

Going to give the blades a very light scuffing w/180 grit like they recommend and paint it and install it.  Going in the water in May 18 and am looking for some big improvements in reverse as well as sailing speed.

Will let you know how I fare.

Steve

[George Pyrpiris]

Just installed the Kiwi prop and I must say.....WOW.....  I'm not kidding! In light to moderate winds boat speed is better than it ever was with the fixed 3 blade...I can't imagine sailing again without a feathering prop.   I was out this past Sunday in 10-12 knots and I was passing everyone even the new Tartans and H. Rassy's in the 40' range.  Those guys are probably having nightmares trying to figure out what's wrong with their boats.  Back to the prop, it's excellent, if you're going to spend money on any one thing go for the this prop.  It's the biggest bang for the performance buck!  A clean and smooth bottom also help.  Backwards can be tricky until you get used to the increase in thrust even at idle.  Be ready to engage in spurts between reverse and neutral, there really is that much power.  No prop walk at all, the boat just starts moving straight back.
New Member,
Just joined and bought the boat end of January, had been on the hard grinding and painting for 6 weeks! New Rudder also.  Even awlgripped the topsides.  Working on the insides now.  The group probably remembers the boat as Loco Viento from the Voyages section.  I'm bringing her back to life (more like back from the dead, no offence to the previous owner) but man was she in disarray.  Couldn't resist though since the price was right and the hull and rig still in one piece.
George Pyrpiris
Viento Loco,
1986, #195 Fin Keel

[Steve Sayian]

Put the Kiwi on and launched last Friday in NE 28 knots of wind and 2.5 foot seas (not at the launch site but in the bay running to the yacht club).

The prop was pitched at 23 degrees (or about 10.5 inches) from the factory.

My M35B with the old 15X9 Michigan 3-blade and a clean bottom would give me about 7.2 knots at 2100 RPM.
The current pitch of 10.5 inches is way too high.  The max RPM with full throttle was 2000 and the speed was only 6.5 knots.  Lots of black smoke coming from exhaust.  Guys at the club said the engine was loading up from the high pitch.

Going to have a diver go over the side and drop the pitch down and see how it goes.  May take a few tries to get it where the RPMs go back up and performance returns.

The reverse on this thing is everything people say!  Coming up to a slip, going from forward to reverse to maneuver the boat is fantastic!   Boat stops on a dime and has immediate response.

Just got the sails on so haven't had a trial sail yet. 

So far, I'm happy with it and see nothing to keep it from getting better.  Highly recommend it if you're looking for an affordable 3 blade feathering prop.

[tonywright]

Feathering prop is definitely the way to go. Having previously used a Maxprop on my Mirage 29, it was a no brainer to go for another feathering prop on my new to me C34. This time I was persuaded to get a J-Prop. Similar marvelous Italian craftmanship in bronze, but much easier to install and adjust than the Maxprop. I have a 3 blade 16 inch. On two outings so far, very impressed with its performance, and judging by Steve's report, the pitch seems about right, permitting the engine to achieve its maximum revs of 2900-3000, but cruising comfortably at 6.7 knots at about 2100-2200 rpm. The power at idle speed in either forward or reverse though does mean shifting into neutral frequently to keep speed low when maneuvering in tight quarters ( a function of the relatively high idle speed of about 900 rpm).

Here is a question for the more experienced. Under power, the stern sits down. The faster you go, the more it sits. We had three people at the stern of the boat last weekend. (Two in the stern seats and me at the helm). At 7+ knots under power, the lower part of the swim platform (is this the right term?) was awash. Is this normal for a MKII? (I quickly eased the speed). Maybe too many folks at the back?

Thanks

Tony

[Wayne]

I have a flexofold.  Really makes a big difference under sail,  Power is revers is weak.  Very weak.  I do still have some prop walk which I like.  Not excessive, but enough to let me drift my stern to port when I want to.

[sail4dale]

I too have a Flexifold.  Love it it is a 15" x 10 which limits my max RPM to about 2400 but pushes me at 7 knots in smooth water.

A nine pitch would allow full RPM. 

It does back beautifully with all the power/speed I need.