Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?

If so, and if water is non-compressible, then what is its effect and how
does it work?


--
Wally
www.makearatherlonglinkthattakesyounowhere.com
Things are always clearer in the cold, post-upload light.

Wally wrote:

Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?

It can if you want it to.


If so, and if water is non-compressible, then what is its effect and how
does it work?

Well, for the best explanation, ask Navvie©. Then he can start an
incomprehensible argument with Gilligan and they can both make up obscure
references and flex their vocabularies.

Probably the definitive reference AFAIK is 'The Aero-Hydrodynamics Of Sailing'
by A.J. Marchaj; you can browse the library or second-hand store and come up
with either that or Marchaj's earlier edition titled 'Sailing Theory &
Practice.' It's pretty heavy going unless you've studied at least some college
level physics. Another option is to spend some time browsing the web. Here's
one of my recent faves.

http://web.mit.edu/2.972/www/reports...sail_boat.html

But the best alt.sailing.asa answer is... what do *you* think it is? Explain
your theory in 300 words or more, and be sure to insult any who dare disagree.

Fresh Breezes- Doug King

Wally,
What does being incompressible have to do with the situation?
Hydrofoils sure generate lift.
So does the keel of most modern boats, but it is "lift" to weather.
This is why you want to set up a little weather helm so the keel (foil)
has some attack angle.
Matt Colie A.Sloop "Bonne Ide'e"

Wally wrote:

Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?

If so, and if water is non-compressible, then what is its effect and how
does it work?


--
Wally
www.makearatherlonglinkthattakesyounowhere.com
Things are always clearer in the cold, post-upload light.

DSK replied:
Wally asked:

Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?
....snip...
If so, and if water is non-compressible, then what is its effect and how
does it work?
....snip...
Probably the definitive reference AFAIK is 'The Aero-Hydrodynamics Of Sailing'
by A.J. Marchaj; you can browse the library or second-hand store and come up
with either that or Marchaj's earlier edition titled 'Sailing Theory &
Practice.' It's pretty heavy going unless you've studied at least some college
level physics. Another option is to spend some time browsing the web. Here's
one of my recent faves.
....snip...

I second the recommendation for Marchaj; I recommended him in this ng
once before when Jax was blathering about "vectors." I find _Sailing
Theory and Practice_ more approachable than _The Aero-hydrodynamics of
Sailing_ but if ya wanna be "scientific"...

They're a lot cheaper from the library.

Frank

On Thu, 20 Nov 2003 13:52:41 GMT, "Wally" wrote:

Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?

If it didn't steering would be difficult wouldn't it?

If so, and if water is non-compressible, then what is its effect and how
does it work?

Higher forces on one side than the other. The same effect that keeps a
water skier on the surface and the reason symmetrical airfoils work.

Rick

If water is non compressible then sound waves would travel though it
instaneously.

RB

"Wally" wrote in message
...
Does the concept of 'lift' apply to the fins or other underwater structure
on a sailboat?

If so, and if water is non-compressible, then what is its effect and how
does it work?


--
Wally
www.makearatherlonglinkthattakesyounowhere.com
Things are always clearer in the cold, post-upload light.

If water is non compressible then sound waves would travel though it
instaneously.


Hibily Dibily Duh?

Bwahahahahaha!

RB

Sound is a longitudinal pressure wave, whereby the energy is propagated as
deformations in the media but the molecules then return to their original
positions and are not propagated. The propagation of a sound wave depends on
the transfer of vibration from one molecule to another.

The speed (u = [¶r/¶P]S) is inversely proportional to the square root of the
adiabatic compressibility times density term.The anomalous nature of both
these physical properties are described above (compressibility, density). At
low temperatures both compressibility and density are high, so causing a
lower speed of sound. As the temperature increases the compressibility drops
and goes through a minimum whereas the density goes through a maximum and
then drops [67]. Combination of these two properties leads to the maximum in
the speed of sound. Increasing the pressure increases the speed of sound and
shifts the maximum to higher temperatures, both in line with the effect on
the density.

It's quite obvious, if compressibility = 0 then the sound of sound is
instantaneous.

"Bobsprit" wrote in message
...
If water is non compressible then sound waves would travel though it
instaneously.


Hibily Dibily Duh?

Bwahahahahaha!

RB

On Fri, 21 Nov 2003 17:22:32 GMT, "Bobsprit" wrote:

Sound is a longitudinal pressure wave, whereby the energy is propagated as
deformations in the media but the molecules then return to their original
positions and are not propagated. The propagation of a sound wave depends on
the transfer of vibration from one molecule to another.

The speed (u = [¶r/¶P]S) is inversely proportional to the square root of the
adiabatic compressibility times density term.The anomalous nature of both
these physical properties are described above (compressibility, density). At
low temperatures both compressibility and density are high, so causing a
lower speed of sound. As the temperature increases the compressibility drops
and goes through a minimum whereas the density goes through a maximum and
then drops [67]. Combination of these two properties leads to the maximum in
the speed of sound. Increasing the pressure increases the speed of sound and
shifts the maximum to higher temperatures, both in line with the effect on
the density.

It's quite obvious, if compressibility = 0 then the sound of sound is
instantaneous.

"Bobsprit" wrote in message
...
If water is non compressible then sound waves would travel though it
instaneously.


Hibily Dibily Duh?

Bwahahahahaha!

RB
True, I think.
Seawater is compressable but not much.
I read somewhere (Bowditch?) that if water was not compressable the
Atlantic would be 78 feet higher. Or was it 400 feet? lol Somewhere
in that range. )
Mark E. Williams