Anyone using a flexofold 2 blade feathering prop

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

Well, on the issue of maintenance of a feathering prop---I would offer this: I have had an Autostream feathering three bladed prop (sold by Martec) on my boat for more than 15 years with no more maintenance than greasing and new zincs at haulout. This included a two year 7500 mile cruise (about 50% motoring) on both sides of Central America with a couple of incidents. My prop picked up a 1" poly propylene line in the water in Miami harbor that sheared all the bolts in my coupling, and tore the cutless bearing out of the shaft strut, but there was no damage to the prop. I have also ingested a log that stopped the engine and, again, no damage to the prop.

I am sure the CS is an improvement over the stock Michigan prop that came with most of the Tartan 37s (which was grossly over pitched on my boat for the W-50), but I highly value the ability to tune the prop to the engine so that it reaches max output at full throttle (pitch is externally adjustable in forward and reverse on the Autostream), the .4 kt sailing improvement, the ability to back with less walk. I think it is the most important improvement I made to my T37 in terms of performance in the 20 years of ownership.

FWIW.

Ray

Tortuga's Lie · **Joined:** 27 Oct 2006 10:32 **Posts:** 827

Ray, what diameter and pitch do you have on your Autostream?

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

It is a 17". Martec told me that other T37s had used that size and it works.

Ray

curriernh · **Joined:** 14 Jul 2011 07:14 **Posts:** 60

Dan over at Flexofold recommends the 17 x 11 for the T37 with a Westerbeke 33. My current prop is a two blade fixed 16 x 11 and seems to work well.

Velera · **Joined:** 29 Dec 2006 09:38 **Posts:** 656

David Gerr's book (Propeller Handbook) is really excellent on these matters. As I understand, you want the biggest diameter you can swing with blade clearance from the hull, but the pitch will vary on each boat depending on the specific engine torque, transmission type, and max rpm. You want to be able to reach max RPM with the boat in flat water (but not more) and then cruise at 80% power so as not to lug your engine. It would be hard to do this without the ability to adjust the prop pitch easily and externally. It took me a few adjustments to get it perfect. I would think that repitching a fixed propeller to get to this point would cost a lot.

solen · **Joined:** 17 Sep 2009 00:00 **Posts:** 34

I just added a Flex 16-11 in June. It works much better than the old (probably) stock unit and has little prop walk. I am still not getting much in the way of RPM and my WB50 - only 2000 or so at hull speed. The engine sounds great and runs "free" at 7 knots but the numbers are nowhere near specs unless my tach is off.

Backing up still seems to works in mysterious ways though.

solen · **Joined:** 17 Sep 2009 00:00 **Posts:** 34

Solen now has a 16x11 (not 17x11) - the results:

forward is excellent with somewhat better rpm - I am now on the flat part of the torque curve but the rpm is low

reverse sucks worse w/o the prop-walk - it needs to idle for a bit to set up the flow over the skeg - unfortunately the wind and inertia does not idle when you need them too - roundabouts are the likely result.

I will be working on a skeg mod either to the shaft support skeg or the rudder skeg

Ardea · **Joined:** 19 Mar 2007 16:40 **Posts:** 195

Do you have your board down when you are backing? Makes a big difference especially in a cross wind.

solen · **Joined:** 17 Sep 2009 00:00 **Posts:** 34

Thanks for the pointer. I usually had it up most of the way in "last years" marina due to lack of clearance. I will experiment.

Tortuga's Lie · **Joined:** 27 Oct 2006 10:32 **Posts:** 827

Tortuga's Lie has launched! And........she has a new prop. I went with a 2 blade Varifold 16 X 11 instead of the Flexofold. The old prop was a Martec two blade folding and the new Varifold has made a huge difference in backing up and stopping Cheers

In forward, she can make hull speed at full throttle and about 6.4 knots at 2200 RPMs. I was real tempted to go with Flexofold but I never got a response form them. I filled out the online inquiry form.....they e-mailed me an automated acknowledgment, but no response after that. I sent two e-mails to their US e-mail address...again nothing! Varifold on the other hand, every e-mail was quickly responded to, and their sales went through without a hiccup.....so Varifold it was and I have no regrets Very Happy

Disclaimer: I have no connection with either Varifold or Flexofold.

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Anyone using a flexofold 2 blade feathering prop

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