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Old 01-05-2014, 14:58   #16
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Re: Sail Trim Article about Twist

Perhaps the core misunderstanding in the blog article is to assume that the geometrical centre of the sail is the centre of effort.

Whenever this happens to be even approximately true, it's only by a fluke. It's a simplifying assumption of the gross variety, useful only for qualitative comparisons between sailplans, or crude assessments of rig balance (relative, rather than absolute)

It's particularly unhelpful when (as here) assessing the influence of twist, and of such things as the fore and aft location of deepest camber.

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Old 01-05-2014, 15:00   #17
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Re: Sail Trim Article about Twist


It ties into the assumption by many that the sails work as seperate foils when in fact they are effectively a aingle surface

"So, rather than appear foolish afterward, I renounce seeming clever now."
William of Baskerville

"You will do foolish things, but do them with enthusiasm."
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Old 01-05-2014, 15:19   #18
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Re: Sail Trim Article about Twist

Hmm, FS, I kind of see what you mean ... I think?

I agree that interaction of adjacent foils is typically overlooked - are you saying this is a similar instance of simplifying assumptions being so misleading as to render conclusions invalid?

- - - - -

I checked another article from the site the OP links to, to see if the twist misexplanation was aberrant. I picked this one at random:

How to handle wind gusts and prevent rounding up | Sailing Blog by NauticEd

Unfortunately, this one is much worse. It appears to have been written by a charlatan.

This writer works backwards from the (correct) 'answer', that heeling causes weather helm, to a (fanciful) explanation, to do with mast rake.

NOT mast inclination to leeward (taking the Cof E with it, which is the major part of the correct explanation) but mast rake AFT !!!

I guess their tagline: "The world's most advanced online sailing education" says it all.


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