"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.