Propeller Size


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Hello all.
I recently bought a new Beta Marine 35 saildrive engine.
i am now in need of a new propeller.
I have a 43ft 'Gitana 43 ' sailboat.
There seem as many propellers as there are opinions on propellers.
However I am seeking your opinions now!
questions, 2 or 3 blade
fixed or folding (almost certainly folding)
supplier?
Type/pitch?
Thoughts on how to come up with the answers to the above questions also very welcome!
Many thanks in advance to you all.
Fair winds.
James
edited by 0 on 26/05/2017
Simon Currin
Simon Currin
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James sorry can 't advise on props but I need to let you know that the Forum will be taken off line from tomorrow (Monday) whilst it is migrated to our new website. So folk won 't be able to respond from tomorrow.
Simon
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hold that thought as they say!
i 'll head to good old Facebook and pop the question.
thanks and good luck with the migration to the new server and website.
Dick
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Hi James,

Complex question(s).

First you must answer for yourself some of the following in no particular order:

Weight of your boat?

Do you race?

Do you run your boat like a motor sailor (turn on your engine below 4-5 knots) or do you like to sail in light airs?

How much thrust do you want from your drive train?

There are fixed and folding, but some of the best props are feathering?

How much do you need reverse and prop walk for maneuvering around marinas?

Then you can go to a prop expert like Chris at Darglow (google Darglow in UK) who is very knowledgably and was very helpful when I addressed some of the same questions a few years ago.

My best, Dick Stevenson, s/v Alchemy
edited by 0 on 26/05/2017
Daria Blackwell
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We just fitted a new feathering prop (MaxProp) and were amazed at how much better propulsion we have in forward gear and dismayed that we now have no prop walk in reverse. In reading the literature that came with the prop, we learned that the new props do not have significant prop walk, which we used very effectively to maneuver in tight spaces in marinas before. :(
edited by DariaBlackwell on 5/27/2017

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Daria Blackwell
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Just found this article on prop comparisons. http://www.yachtingmonthly.com/gear/folding-and-feathering-propeller-test-29807 Perhaps that will give you some ideas.

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Ginger
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[quote=DariaBlackwell]We just fitted a new feathering prop (MaxProp) and were amazed at how much better propulsion we have in forward gear and dismayed that we now have no prop walk in reverse. In reading the literature that came with the prop, we learned that the new props do not have significant prop walk, which we used very effectively to maneuver in tight spaces in marinas before. :(
edited by DariaBlackwell on 5/27/2017[/quote]
Ginger
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Hi Daria and all,
I find your report somewhat curious. I am on my 4th Max-prop over 2 boats and a number of decades and I have found usable prop walk on all of them. I do admit, that it has been too long to remember whether my fixed prop had more prop walk, but I am clear that I have enough for reasonable maneuvering in marinas (without a bow thruster).
I will attest that the vastly increased power in reverse over fixed props (the blades feather so thrust in reverse equals thrust in forward) is a terrific benefit in maneuvering in tight spaces.
It may be that one needs to be more aggressive with the throttle (from a stand-still position or when going from reverse to forward or vice versa) to maximize prop walk in tight places.
Our latest MaxProp is a four bladed one of a larger diameter and quite a bit more blade acreage, bought so we have more thrust in adverse conditions. This is our third season with this prop and we are very happy.
BTW, the go-to book on props is, appropriately, called the Propeller Handbook (or something like that) by Dave Gerr. It is superb, and maybe a bit technical.
My best, Dick Stevenson, s/v Alchemy
Daria Blackwell
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Dick,
We are just as nonplussed as you. We had major prop walk on our old prop -- which was an older MaxProp design and much smaller blade area than the new one. We tried everything in testing this new one. No matter how hard or fast we pushed it in reverse, it did not swing the stern. I do not have the literature at home as it's on the boat, but it does say that the new design eliminates prop walk. In a few days, I'll post their notes here for reference.

There is a note on another Forum that people overpitch their MaxProp to create prop walk -- apparently the Dashews used that effectively instead of a bow thruster on one of their boats.

BTW, we also found that in order for it to feather after shutting the engine down, we had to keep the engine in forward gear at fairly high rpms or it didn't work.

Daria

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Ginger
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Hi Daria,
Nonplussed is such a great word. I look forward to hearing about your researches. Ours is 4 years old and I had not heard about any claim of “no prop walk” and it would not be a selling point for me. I over-pitch a little and will do a little more. I had not heard about it affecting prop walk, so that may contribute some to what I experience.
I would call Chris at Darglow. I would except I am no longer in the UK. I found him very knowledgeable about props and especially Max Props.
My best, Dick
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