Feathering or Folding Props - Increase Performance?

[Elie]

I have experienced all types of props with my various boats. - Folding racing type are almost useless trying to backup, but are acceptable motoring forward, exept in heavy sea; - Feathering like Maxprop is slightly less efficient than a fix prop going forward, but much better while going backward. This can be explained by the fact of symetrical shape of the blades(not as good as a cupped one but going backward, is as as going forward, with no prop walk. In my present boat, I use a Brunton Autoprop. Amazing adaptability to different conditions by its clever self piching ability. The best when going against head winds and big seas, motorsailing or going in flat waters. However, it is a bit complicated piece of machinery, and any slight imbalance in the drive shaft components creates tremendous vibrations. And the bearing need to be replaced regulary.

[mark_morwood]

You might want to also look at the autostream feathering prop. Seahawk: Autostream Self Feathering Propellers for Sailing Yachts & Sailboats

I just ordered a pair after also looking at the kiwi prop and others.

Mark.

[fastcat435]

On the prototype FastCat 435 we started out with 2 blade fixed props because the flex o fold racing props had not arrived yet, The speeds has increase with 5 to 10 % while sailing depending on the winds after changing to the folding props with 10 knots of wind 90 degrees app from 8 to 9.2 knots , the motoring speed dropped from max 8.8 to 8.4 knots , we can point higher and on the ocean crossings it makes a real difference. If price is no issue I would recommend the 3 blade gori folding props with overdrive setting , I have these on my St francis and they work great , excellent handling under power and folded when sailing , otherwise the flex o fold 2 blade folding are good.

[fastcat435]

hello mark we just installed a pair of autostreams to a fastcat and they work great, make sure that they are adjusted to the right max rpm setting , otherwise you will not get the right speed and install rope cutters because they like rope a lot

[Moby Dick]

Mark_moorwood : why Autostream?

Elie: Are you using 2 or 3 blade autoprop? New design (less frequent bearing replacement) or old?

Fastcat 435: Autostream 'work great' but 'like rope' Any details ?

Fastcat 435: well yes folders would work best when sailing or (when new) not too badly motoring ahead. How about reverse, which you need a LOT in a cat of course?

Thanks

[fastcat435]

Because of the blade shape they tend to grab ropes fast so that is why I would advise to get rope cutters for the rest these props are great make sure to renew your anodes in time .

[The South African]

Be aware of locking a Volvo's engine's prop in reverse when sailing - the manual warns against that - it could damage the engine because of water intake - ot something like that.

[fastcat435]

Motoring astern with the flex o fold racing folding props is fine, no problems there, just the stopping distance is a little longer so go slow if you can. Maneuvering works fine with these props you need to rev a little higher in order to get moving

[Elie]

My Autoprop is a 3 bladed design, and I replaced all the bearings and the races(not from Autoprop!). On top of that I have installed a shaft coupling that absorb large shaft movements and vibrations. I believe that the choice is base on what you intend to do. In my case the most important wast not the drag, but rather good control to back up(no prop walk) and power going forward, even in strong winds and sea. This auto pitch feature works quite well. In fact, I believe that there is no perfect solution : Fixed prop is the simplest, most has the most drag, lots of prop walk and in fact is perfect only at the speed it is made for; Newer folding props like Gori, Flex-o-fold, are very good forward, so so going astern, and the need serious maintenance after a while; Feathering props are very powerful going back, have little drag, but are a bit inefficient forward, and sometimes jam !. Autoprop are very good going forward and astern, but the shaft alignment need be perfect, the maintenance may be expensive(bearing replacement!). An imperfect world, full of compromises! http://www.cruisersforum.com/images/...n_rolleyes.gif http://www.cruisersforum.com/images/...n_rolleyes.gif

[ireaney]

Thanks for all the input, this is very informative for me, but again I go back to the VARIFOLD prop that Bruntons do which is different from the Autoprop but is it similar to the Gori - or am I just being thick - any views on the Varifold and it's performance. Thanks in advance - Ian

[Elie]

Hi, I have no experience with Varifold, but I heard lots of good thing about them from a racer that uses it on its Beneteau 47.7, equiped for serious racing. So it most be very good drag wise, and it seems to do the job motoring. Have a good day.

[mark_morwood]

Originally Posted by fastcat435

Because of the blade shape they tend to grab ropes fast so that is why I would advise to get rope cutters for the rest these props are great make sure to renew your anodes in time .

Which rope cutters did you install with the Autostreams? I have saildrives and it was not obvious how to do a reasonable install with the combination of sail drive and feathering prop.

Mark.

[mark_morwood]

Originally Posted by Moby Dick

Mark_moorwood : why Autostream?

Thanks

1st. I was looking for feathering not folding. I wanted reduced drag under sail, with good handling in close quarters in reverse and forward. I'm a great believer when maneuvering around docks and other boats in slow speed with liberal applications of power.

2nd. Not having had real experience with any, it was a decision based on the info I could glean from others. The final straw for the Autostream was what seemed like an honest and straightforward overview of them and other props from the manufacturers rep at the Newport boat show as well as a good discount.

Kiwi props cost a lot less, but they were sufficiently different to everything else that I was nervous. I was however very interested. I think if I had a smaller boat I wouldn't have gone with them.

Maxprops seem reliable but I liked the evolution of the Autostream design.

Autoprops cost more and I wasn't convinced about the self pitching being a big benefit.

Mark.

[fastcat435]

The
following ropecutters work fine with both yanmar and volvo saildrives
http://www.ropestripper.com

Make sure you order the type for 3 bladed props
Good luck and greetings

[Yotboss]

I installed 3-blade Flex-O-Folds on my Lagoon 42 about five years ago. Speed gain under sail was about 10% with the transmissions locked in reverse. (Yes, free-spinning props DO create drag). There was a huge improvement in reverse over the original 2-blade fixed props and she does much better at powering through big chop.

I found the Flex-O-Folds easy to install and the only maintenance has been a good cleaning at haul-outs and zincs. The zincs were expensive at first, but now an after-market company makes them, so it's tolerable. As was mentioned here before, getting the correct pitch is critical so that your engine gets up to speed. All in all, it was a great investment and the improvement in sailing, motoring and close-in maneuvering has been well worth it.

Tom