"DSK" wrote in message
. ..
I guess once people got the idea of fluid movement around restrictions
creating usable pressure differentials, it became just a matter of
experimenting with different shapes and fluids.

When you say "experimenting with different fluids" do you mean like sulfur
dioxide? Does it increase or decrease the efficiency of sails?


The USS Constitution demonstrated that in light air, the speed of the ship
could be increased by spraying water on the sails.

Documented he

http://www.history.navy.mil/photos/e...a/const-es.htm

Not only that the USS Constitution clearly demonstrated she could sail
directly into the wind:

http://www.americanheritage.com/arti...955_3_56.shtml

If that is not enough, here the USS Constitution is the first US warship to
to have propellers:

http://www.usni.org/navalhistory/art...ingtonApr.html





Think of this. The sail has the most power delivered to it when the
residual wind velocity is zero after interacting with the sail.


I think that's a mistaken assumption. The sail has the most power
delivered to it when it is developing max differential pressure
theoretically possible for it's density & initial velocity.

The maximum pressure differential occurs for any given windspeed when the
airspeed on the low pressure side of the sail is zero. If the velocity on
the "low pressure side" equals the velocity on the high pressure side there
is no lift.





The most efficient sail design reuses the wind velocity, similar to the
stages on a turbine engine.


True. That's why the America's Cup racers all have to be limited by rule
as for how many masts they can rig. It got to be a PITA inventing new
terms for the fifteenth & sixteenth mizzen.

They should be allowed to put masts out the sides.




The most efficient sail design of all time was developed in Northern
Italy. The design was lost during the early Renaissance, only to be
recently uncovered during and archeological dig in a shallow bay. The
sails reused the wind many times over with each "stage" adjusted for the
reduced wind velocity. The sails are a series of "slats" with multiple
gaps and adjustable angles of attack. They are referred to as Venetian
Sails.


Now that was a very illuminating little essay

Glaring, indeed.




Scout wrote:
One would think that the sheer volume of air would make its efficient use
a non-issue. Unless the point is the area of the cross-section of air
available to a given size boat is limited. If that makes any sense.

Congrats, you've re-invented the term "sail area"

Fresh Breezes- Doug King