Richard Casady wrote:
On Sun, 14 Oct 2007 20:37:22 -0700, Stephen Trapani
wrote:

The advertisement never claimed to impart forward force going directly
into the wind. All they claimed was that they could somehow decrease the
load on the motor or increase the efficiency of the system.

Those two sentences mean the same thing. Raising a sail when headed
directly into the wind will increase the aerodynamic drag acting on
the boat, and reduce speed.

Putting wings on a plane increases aerodynamic drag acting on the plane,
yet it increases the speed, right?

Stephen