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11-02-2013, 16:41
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#61
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Registered User
Join Date: May 2006
Location: Nicholasville, Kentucky
Boat: 15 foot Canoe
Posts: 14,191
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Re: Settle an argument
Wing shaped sails are all "bunk?" That's why racer's sails are all completely flat, right?
There are some boats, such as Sunfish, that basically have a flat sail but they are few and far between. Sunfish is a simple lateen design that sails pretty well for being a flat sailed lateen but if you put a marconi laser sail which has a win shape on a Sunfish hull it sails very much better to windward even though they have the same sail area.
__________________
John
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11-02-2013, 16:47
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#62
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Marine Service Provider
Join Date: Aug 2010
Location: north carolina
Boat: command yachtsdouglas32
Posts: 3,113
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Re: Settle an argument
Quote:
Originally Posted by RainDog
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My all time favorite is the flying toilet seat!
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11-02-2013, 16:52
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#63
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Registered User
Join Date: Sep 2012
Location: Washington State
Boat: Colvin, Saugeen Witch (Aluminum), 34'
Posts: 2,275
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Re: Settle an argument
Quote:
Originally Posted by Tscott8201
Ok, had a friendly argument with my father in law this weekend. Last time we rented a sailboat for a day the instructor commented on the importance of sail trimming due to the fact the sail is basically a wing. Later on that day my father in law brings up that he believes this is all mumbo jumbo and that the "wing effect" is basically oversold. He claims that a perfectly workable sail could be made out of a flat solid sheet of material with no curve and you would get decent performance out of it. Not as good a a curved sail, but almost as good. I told him it might work but would basically be crap and give little to no forward thrust. Who is right?
Tom
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I think they are both right - or wrong. It depends what value you assign to the words "decent" and "crap".
The aerobatic aircraft analogy is not the best because even the symmetrical wings have a large radius leading edge. This helps tremendously in keeping flow attatched at higher angles of attack. Then again, If the father-in-law is assuming that the sailboat mast (large radius leading edge) is in place ahead of the flat sail, then he is a little bit more correct.
Plane is an early model of the iconic "Pitts Special". Wings are asymmetrical. Flies fine inverted although it loses about 20 knots if I do not add power.
Water in background is the Strait of Juan de Fuca.
Steve
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11-02-2013, 17:04
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#64
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Registered User
Join Date: Nov 2011
Location: Montegut LA.
Boat: Now we need to get her to Louisiana !! she's ours
Posts: 3,421
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Re: Settle an argument
I know from beans about airplanes!! My question is where do ya stand wirh Junk sails ?? flat? curved, in between? I just wonder?
__________________
Bob and Connie
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11-02-2013, 17:20
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#65
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Registered User
Join Date: Sep 2012
Location: Washington State
Boat: Colvin, Saugeen Witch (Aluminum), 34'
Posts: 2,275
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Re: Settle an argument
Quote:
Originally Posted by bobconnie
I know from beans about airplanes!! My question is where do ya stand wirh Junk sails ?? flat? curved, in between? I just wonder?
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I know from beans about Junk sails!! I dont even know witch is better - mast on the windward side or downwind side?
In-spite of the stiff, full length batons, It seems there is still a fair bit of camber in between them.
Do the gaff rigged gazelles sail to windward better that the Junk rigs?
Steve
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11-02-2013, 18:54
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#66
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Registered User
Join Date: Mar 2008
Location: Calgary, AB, Canada
Posts: 6,252
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Re: Settle an argument
Tom Whidden, in the Art and Science of Sails, questions the "popular theory". I won't go through the whole chapter.
__________________
CRYA Yachtmaster Ocean Instructor Evaluator, Sail
IYT Yachtmaster Coastal Instructor
As I sail, I praise God, and care not. (Luke Foxe)
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11-02-2013, 20:31
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#67
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Moderator Emeritus
Join Date: Nov 2008
Location: Lived aboard & cruised for 45 years,- now on a chair in my walk-in closet.
Boat: Morgan OI 413 1973 - Aythya
Posts: 8,466
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Re: Settle an argument
Quote:
Originally Posted by Bash
Thinking of the latter as the application of the former. ...............................
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I know this concern doesn't merit time on this post, but your description confirms my thoughts. Engineers are applying science and engineering is a scientific endeavor. Engineers are working at a level of understanding that is not rote application worker bee,- "hook the red wire to terminal B". Engineering is science, no less than a duck is a bird. Engineers are required to be physicist to a great degree. Scientists are not all in the "Irvory Tower". .......but this all comes down to a consensus that we are probably in total agreement.
Anyway, as with the other agreement, the sail is a "wing" and increasing behaves as a "wing" as the heading is closer to the wind.
__________________
Take care and joy, Aythya crew
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12-02-2013, 04:18
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#68
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Registered User
Join Date: Aug 2009
Location: Hudson Valley N.Y.
Boat: contessa 32
Posts: 826
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Re: Settle an argument
Huh??.......I thought sails worked by magic.
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12-02-2013, 04:32
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#69
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Registered User
Join Date: Dec 2012
Location: New Orleans
Boat: Bruce Roberts 44 Ofshore
Posts: 2,859
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Re: Settle an argument
Quote:
Originally Posted by mrohr
Huh??.......I thought sails worked by magic.
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Oh, but it IS magic! I thought everyone knew this from the first time they saw burbling wake astern, felt the heel of the boat and the little tugs from the tiller and heard nothing but water rushing by, pausing to give a friendly slap to the hull now and then.
__________________
GrowleyMonster
1979 Bruce Roberts Offshore 44, BRUTE FORCE
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13-02-2013, 05:30
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#70
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Registered User
Join Date: Nov 2012
Location: North Florida
Posts: 104
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Re: Settle an argument
Wow, I had no idea a simple question would spark so much debate. I also had no idea the theory for the cause of lift was in question. Great information guys.
Thanks,
Tom
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