Flexofold Prop

Dean Gillies

Interesting thread. 

I'm also changing out my fixed prop, but was leaning towards the Autoprop which was specified by Amel on other 54's.  Was there any compelling reason you chose flexofold over the Autoprop Patrick?

The Autoprop is priced around 2700GBP+VAT. Not sure how that compares to the flexofold?

SY Stella
Amel 54 #154


I don't know the price in GB, but the US price for a MaxProp feathering prop is about the same as the price you quoted for the Autoprop at current exchange rates.  

My understanding is that an older SM can't fit an Autoprop (they were delivered with a MaxProp) because the shaft is so short the blades can hit the c-drive housing as they flop around.

The Autoprop is certainly in theory (and in their advertising) more efficient, but there is no real-world difference I have ever heard of in boat speed and engine RPM between SM's with an Autoprop and a properly pitched MaxProp at cruising speed.

Also in theory, the Autoprop is more efficient when motorsailing.  I can't speak to that, I haven't ever motorsailed for any distance, if the sails are working, I am sailing. If you do a lot of motorsailing, it might be important.

Anecdotally, the Autoprop is more sensitive to fouling which unbalances the blades and prevents them from taking the right pitch.  All props are MUCH less efficient with even very light fouling, but the Autoprop seems to load up the engine significantly rather than just slowing the boat down.  Again, that is just a summary of my take on the flavor of posts here.

If I had an Autoprop I'd certainly keep it.  If I needed a new prop, I'd likely stick with the kind of Maxprop that come with my SM (even if an Autoprop could fit!)  It is simple (no bearings), grease can be renewed underwater, and I have many years of experience with it--for what that's worth.

But if an Autoprop was significantly cheaper, I'd go that way.

Bill Kinney
SM160, Harmonie
Fort Lauderdale, FL


Another consideration:  On KAIMI we have a 4 BLADED VARIPROP "BLUE WATER" MODEL.  This "unboxing video" shows the shape and operation of the prop and its SIZE.  Ours is a DF112 as well https://www.youtube.com/watch?v=C3RvbX1Oa54

After operating it for over 4 years I am sold on it.  Its reverse seems as powerful as its forward force.  Solid power in fwd or rev from a dead stop or at slow speeds.  In motoring or motorsailing it provides good, fast propulsion and during sailing very little drag.  Easy prop removal and bomb proof attachment to the shaft--see brochure.  Seems well matched to the Amel with good cruising speeds from 1600-2700, quite a bit of our cruising motoring is up and down from 2000  It will let you go above 3200 with no problem--can't remember how high it goes.  It seems to like motor sailing as well when there is lower load for a given rpm.  Works well with our shaft brakes. The German based company will immediately respond to emails or phone calls.  http://www.spw-gmbh.de/en/features-of-the-variprop.html   also  http://www.spw-gmbh.de/en/variprop-2-3-and-4-blade.html

2 Years in the water (boat is presently on the hard) and no need to change the prop nose cone zinc (or our rudder zincs), perhaps due to a galvanic isolator.

A video on their site is informative https://www.youtube.com/watch?time_continue=22&v=-CqLFaM3qvc  If you look at the design in action you can see why it is powerful in both fwd and rev, why it has a lot of blade and why it has low drag when feathered.

Variprop propaganda--

"4-Blade-Power — the VARIPROP 'Blue Water'
Especially in blue water conditions, excessive blade loading causes cavitational noises, bubbles on blades and resulting loss of power, just when you need it most in the trough.

The solution is the VARIPROP 4-Blade — to-date worlds most modern 4-blade feathering propeller, with 30% larger blade areas, less blade loading, much greater thrust and undiminished power."

They are worth a call at least I think.  They will definitely have our 2004 SM Redline on file (Yanmar).

Bob and Suzanne, Colorado
KAIMI SM 429, Malta


VARIPROP--This is follow-up on the model, size and pricing information that I received back from the German company S.P.W. GmbH  .   The size used on our Redline SM was a DF-112, ø 22" x 16" pitch ahead x 14" pitch astern LH rotation for ISO 35.  The current pricing is €4.469,80.  I had asked them about other Amels and their response was "
Yes, we fit... mostly 4 blades onto AMEL Yachts. Some were smaller sizes, some same DF-112 types  as well, depends on the Yacht and engine details."

Hope this is helpful to anyone inquiring regarding the Variprop.  I do have their pdf price list if anyone needs it.

Bob, KAIMI SM429