PIM,

You asked for help in explaining your description of the action of a
sail and we only gave you negative comments. Let me give a try to put
you thoughts into my words and we'll let Neal pick at both of us.

It isn't going to be easy as sailors have always gotten good results
with sailing by tell-tales and stream lined flows and the Bernoulli
Theorem;
But, let's give it a try------

So, the difference in your thoughts is that the sail pushes the boat by
using the reaction of the action caused by the bending of the air on the
curved lee side of the sail. ( Action and Reaction)

This happens by the curved sail passing thru the air, or more precisely,
the air passing around the curved sail. The action being the bending
back of the air causing a drafting effect towards the windward side of
the sail. This action, created by curved section creates a reaction to
the windward side of the sail causing a drafting force to push the sail
and the boat. With the help of the Keel this reactive force is converted
to an angular force driving the boat forward.

Now, why does this happen? The cause of this leeward action is the
DEFLECTION of the air away from the curve leeward side of the sail.
This deflection creates a void which causes the air in front of the sail
to rush into the void created by the deflected air. This in turn creates
the backward draft that creates the reactive. equal and opposite,
forward draft on the windward side of the sail. This is the pressure
that drives the boat forward

Does that sound correct, PIM? That would satisfy the tell-tales and give
reason for the upper windward tell-tale to be dancing as tell-tale
sailor know is sailing in the "GROVE"

The only difference now is we are using positive pressure to push rather
negative pressure to pull. We still create a higher velocity of air on
the lee side but replace it with new air, which doesn't have to accept
the Equal Transit Time

I hope you notice I made no mention of a wing!

OK! I'm ready for the flaming replies

Ole Thom