"Gilligan" wrote in message
. ..

"Scout" 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.
Scout



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

Any leftover wind velocity is wasted energy, just like left over stean in
a steam engine.

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

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.

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.
Scout