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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > 3 blade prop or two blade folder
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Thread: 3 blade prop or two blade folder Reply to Thread
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Topic Review (Newest First)
07-10-2013 12:03 AM
TQA
Re: 3 blade prop or two blade folder

Quote:
Originally Posted by Geoff54 View Post
Let me get this straight.

You are over propped but you are happy with the sailing performance with a fixed prop. You are cruising in an area where fouling is a problem. But instead of getting a smaller or finer pitch fixed prop which is cheap, functional and can't fail (unless it falls off ), you are considering spending a bunch more on a folder (or similar), which requires more care & maintenance.. and introduces another thing that could go wrong. Hmmmmm. What am I missing here?

If sailing performance was an issue I could understand it but....
Well I think I need a new prop. As I am my current prop is over dia or overpitched I think I can drop down to a two bladed prop of the same diameter.

So I can get a folder and go a little faster under sail. I suppose that I won't see the degree of benefit that someone who sails most of the time in light airs would but it should be faster. I like fast. I mean I put up with a full batten main and fly the spi when I can.

But you are the voice of reason on fouling, four weeks in Falmouth Harbour Antigua turns a prop into a flowerpot.
07-09-2013 05:54 PM
bobperry
Re: 3 blade prop or two blade folder

Accurate prop drag numbers have been around for many years. There is a good reason why every performance oriented boat uses a folding or feathering prop. The most sophisticated high performance boats may even use retracting props. If you don't retract your prop we know that a sail drive has lower drag that a shaft and a P bracket. There is no question that your boat will sail faster with a folding or feathering prop and that's why any rating rule will credit or ding you for the type of prop you use.

If you don't care about efficiency under sail just don't sweat it. But that's a big bucket you are dragging around with a fixed blade prop. I know. I did it for three years. During that time I learned that with a fixed three blade I sailed upwind about the same speed as a Baba 40. Both boats had very good sails ands the Baba had the tall rig. But with a folding or feathering prop I would have had a definite edge. I kept the fixed blade prop because I liked its performance under power and in Puget Sound we motor a lot.
07-09-2013 04:52 PM
BarryL
Re: 3 blade prop or two blade folder

Hello,

IMHO, if it's windy where you sail (and it sounds like it is) then you won't see any significant performance improvement with a folding / feathering prop. Your boat is already sailing about as fast as possible. Changing the prop (or even removing a prop) can't make a boat that is going top speed go any faster.

If you were frequently sailing in light air, then the folding / feathering prop could make a big difference.

Barry
07-09-2013 02:45 PM
Geoff54
Re: 3 blade prop or two blade folder

Let me get this straight.

You are over propped but you are happy with the sailing performance with a fixed prop. You are cruising in an area where fouling is a problem. But instead of getting a smaller or finer pitch fixed prop which is cheap, functional and can't fail (unless it falls off ), you are considering spending a bunch more on a folder (or similar), which requires more care & maintenance.. and introduces another thing that could go wrong. Hmmmmm. What am I missing here?

If sailing performance was an issue I could understand it but....
07-09-2013 01:33 PM
bobperry
Re: 3 blade prop or two blade folder

TQA:
Yes, think that's a good way to go. Only caveat with the Gori is that growth on the prop may prevent it from opening properly. Normal care of your bottom should eliminate that problem.
07-09-2013 01:07 PM
kellysails
Re: 3 blade prop or two blade folder

I have a 4 blade MaxProp Classic II on my SD50 saildrive. I love it. I get nearly zero prop walk in reverse. The boat really behaves so well in reverse that I actually find it easier to go stern into slips.
07-09-2013 12:59 PM
TQA
Re: 3 blade prop or two blade folder

Hmm so the panel thinks going folding is a good idea with the Gori edging out the non geared types.

I will keep the 3 blader as a spare or in case I lose my marbles and decide to motor sail up wind for days at a time.
07-09-2013 12:15 PM
killarney_sailor
Re: 3 blade prop or two blade folder

I had a Maxprop on the last boat and loved it, but have not been able to justify the expensive of one for the new boat (or at least not had the money for one that could not be more usefully spent on something else. We have a standard 3 blade and it works fine. Like you we do not motor very much.
07-09-2013 12:09 PM
sony2000
Re: 3 blade prop or two blade folder

A single blade has the least loss from drag (friction), but can't be balanced efficiently. So the next best is 2 bladed.
07-09-2013 07:32 AM
Johnnycatt
Re: 3 blade prop or two blade folder

for what it's worth, I am an old evenrude mechanic.. I remember somewhere in my training one of the instructors saying that the best prop would theoretically be a "single blade." I cannot remember what the logic was, but I know two baldes was considered the best option for speed, 3 blades was for general purpose and 4 blades was typically for towing...
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