my statement was in respone to the secondary posting that said understanding
wing arifoils was 3/4 of understanding sail airfoils.

no, the keel has not a thing to do with understanding how a sail works.
nothing.

it does have something to do with how a sailboat works, but not a thing on
how
a sail works.


You are correct.

But the initial posting was :"I'm trying to understand how a boat can
sail against the wind."

Understanding the sail as airfoil is not 100% of the answer. One must
also consider the effect of the keel.

Jack

_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
_________________________________________________ _

Jax,
Maybe I didn't word it clearly. I said "A boat goes to windward by
generating lift from its sail, just like an aircraft's wing. If you
understand a wing you are 3/4 of the way there."

I meant 3/4 of the way towards understanding how a boat goes to windward
- not 3/4 of understanding sail airfoils. The other 1/4 being to turn
it on its end and match it with a keel, centreboard etc.

But this isn't helping Axel very much. Do you know of any good online
diagrams we could point him at? I admit I can't be bothered to search
for one...

And.

JAXAshby wrote:

my statement was in respone to the secondary posting that said understanding
wing arifoils was 3/4 of understanding sail airfoils.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.

Jax,
Maybe I didn't word it clearly. I said "A boat goes to windward by
generating lift from its sail, just like an aircraft's wing. If you
understand a wing you are 3/4 of the way there."

I meant 3/4 of the way towards understanding how a boat goes to windward
- not 3/4 of understanding sail airfoils. The other 1/4 being to turn
it on its end and match it with a keel, centreboard etc.

But this isn't helping Axel very much. Do you know of any good online
diagrams we could point him at? I admit I can't be bothered to search
for one...

And.

JAXAshby wrote:

my statement was in respone to the secondary posting that said
understanding
wing arifoils was 3/4 of understanding sail airfoils.

On 16 Aug 2004 01:38:25 GMT, (JAXAshby) wrote:

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
__________________________________________________
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
__________________________________________________

jack, you also need air breath, a hull that floats, a rudder, sunscreen
protection and maybe condoms if you might get lucky.

However, none of those in anyway affect how the airfoil on a sail works, which
is 100% the same as the way the the airfoil on a wing works.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
_________________________________________________ _

You guys are getting boring. Maybe the two of you can get together by
ganging up on me!

:-)


"JAXAshby" wrote in message
...
jack, you also need air breath, a hull that floats, a rudder, sunscreen
protection and maybe condoms if you might get lucky.

However, none of those in anyway affect how the airfoil on a sail works,
which
is 100% the same as the way the the airfoil on a wing works.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol
or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
_________________________________________________ _

Hey Guys,

Don't you know Jax well enough by now. If he has an answer, he'll sure
hell modify the question to fit his answer. Re-quoting the original
question does absolutely no good.

OT

if you know the olde fart well enough, you notice olde thom doesn't make much
sense in any post after about 4:00 in the afternoon.

From: (Thom Stewart)
Date: 8/17/2004 ------------------ 10:26 PM -------------------- Eastern
Daylight Time
Message-id:

Hey Guys,

Don't you know Jax well enough by now. If he has an answer, he'll sure
hell modify the question to fit his answer. Re-quoting the original
question does absolutely no good.

OT