Folding prop question

[rbh1515]

I'm buying a new 28 foot sailboat (for daysailing/cruising), and it comes with the usual fixed prop. I've been reading up on folding and feathering props and am leaning towards a Flex-O-Fold 2 blade prop. Anyone have any experience with the Flex-O-Fold? My main goal is to give better sailing performance. I hear that it will also reduce propwalk. Rob

[haffiman37]

Have a look at my webpage:
http://www.geocities.com/haffiman37
Look in the test section: Engine and propellers.
I used (still using) a 3 blade Flex O fold an is very pleased with it.
What I do not recomend, you will find there too!

[LaLeLu]

We have a 3 blade auto prop. You can really feel a diff in speed when the prop folds. While I was in the galley when were sailing up the ICW last weekend, I could "feel" some sort of resistance under the hull. I yelled up to my husband to check that it was in gear - it was not. (On our boat the tranny has to be in gear to fold). Once he put it in gear, I could "feel" the resistance go away. We have also watched our speed go up about 1 knot as the prop folds. People either love or hate autoprops - and they are tremendously expensive, so I am not necessarily trying to sell you on that brand. You'll have to do your own research in that regard. I am just here to endorse the virtues of a folding prop in general.

[TejasSailer]

You've probably already read the article. The April 2006 issue of sailing magazine has an article on folding props. About Flex-O-Fold the article says in part:

"Flex-O-Fold folding propellers, meanwhile , are the choice fo many high-performance boat-builders, ... J-Boat, Dehler, X-Yachts, Najad and Swan."

"In addition ... to [the] standard ... models, Flex-O-Fold also offers a two blade racing model .... [that] according to the company ... will induce 20 to 30 percent less drag ...."

[Sailormon6]

Is it true, as rbh1515 says, that a folding prop reduces prop walk? Does it reduce it so much that it becomes difficult to rotate the boat in a tight radius? If so, how do you rotate the boat?

[haffiman37]

All single propellers produce 'prop walk', that is why Volvo introduced the duo prop to eliminate the effect. You have it in forward as well as reverse. The higher efficiency of the propeller (pitch and area) the more alk at low speed. You have it but rearly notice it in forward on a sailingboat. When going in reverse most boats pulls the stern to port, depending on propeller rotation. Going in reverse the trick is to get up some speed, reduce the throtle and then you may in most cases steer where you want! The more power you give at low speed, the more effect of the propwalk. Just live with it and learn how to handle it. If you want a propulsion system without prop walk go for water jet!

[Fstbttms]

Originally Posted by LaLeLu

We have a 3 blade auto prop. I am just here to endorse the virtues of a folding prop in general.

Just a gentle FYI, the Autoprop is a feathering prop, not a folder.

[Rickm505]

You might want take a few minutes and read a comprehensive technical paper and comparison on folding props.

http://home.cfl.rr.com/rickm505/propeller.pdf

[haffiman37]

To most people I think the tests at the Flex O Fold homepage is easier to read and understand.The results seems to be almost the same. However for some reason tests at sea and tests in laboratories are two different things. Remember you are to use the propeller at sea and not in a test tank! Check out this:
http://www.flexofold.com

[Rickm505]

" Remember you are to use the propeller at sea and not in a test tank! "

What an interesting observation, and one I have to comment on:

First, when comparing different brands of propellers, your test criteria have to be identical or the comparison is worthless... right? Hence the MIT test tank.

Second, Thrust is thrust. That paper does a terrific job on comparing several major brands. And ... it's unbiased.

Third, Are you affiliated with the brand you're recommending?

Thanks

Rick in Florida