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DSK
 
Posts: n/a
Default Sail Aerodynamics

MC wrote:


....Never seen the main luff
rising to windward? It's due to the slot and the mast.


Why, no, Navvie, I never have!

Are you *sure* that a luff (or 'bubble' as it's often called) along the main
luff is due to the slot & the mast? Who'd a thunk it?



Also if you look at the photos of the sail, they are much flatter than
often said to be ideal (there is no reference to wind speed, it might
be light air) and the drafts are aft.


Yes they are flat, but these sails are trimmed for very very close
sailing -probably much closer than most of the nags sailed here could
achieve.


If that's true, then why are the photos of your mainsail, that you're so
proud of, not shaped at all like the ones in the sailmakers web site?

...Note also that the apparent wind is 22 degrees


Gee, Navvie, do you hold a protractor up to your computer screen?




....Also it shows a vortex off the
head of the jib.... now the question is, does a frac rig benefit
because the mainsail supresses the jib's tip vortex, or does the jib
vortex hurt the drive of the mainsail?


Yes, the benefit is from the greater adjustability of the frac. rig.


And the adjustability has *what* to do with the vortex?

I was hoping that somebody might like to discuss rig tuning & sail trim.
Navvie, you are a font of meaningless, self-congratulatory prattle. And
you're not as funny as Boobsie.

DSK