Ronald Raygun wrote:
Wilbur Hubbard wrote:

"Steve Firth" wrote in message
.. .
Wilbur Hubbard wrote:
Among other things, they claim to be able to create something from
nothing. The advert states, "Even in dead air the apparent wind when
motorsailing generates lift and reduces the amount of engine power
needed to maintain the same speed the engine would produce on its
own."
Huh? Tell me I ain't dreaming . . .
You're not dreaming, they're right and you don't understand physics.

Is there any more help that you need?
I had the utmost confidence that the post would usher forth the Looney
bin, perpetual motion crowd! Welcome, to you, sir. It's good to see a
Brit is the first to insert his foot into his mouth.

Well, perhaps the idea is that when sailing into a "dead" wind, the
sails be set horizontally, so that the lift generated by them is in
the direction which is traditionally associated with "lift", i.e. "up".
Like hydrofoils, these aerofoils would cause the hull to ride a fraction
of an inch higher in the water, reducing water resistance.

Alternatively, the idea might be to back the sails, which would generate
a sideways force on the boat, so that it actually travels with some
leeway. If the leeway angle is big enough, and the drag from all this
doesn't slow down the forwards speed much, the effective speed will be
enhanced by the Pythagoras effect. The helm must be instructed to steer
a few degrees off the intended destination, to compensate for this
beneficial leeway.

Ronald Raygun might be right, if the boat is designed in such a way to
take advantage of these effects. The actual effect proposed by NORDHAVN
will have to be known to know if Wilbur is entirely wrong, but we do
know that Wilbur is partly wrong because NORDHAVN doesn't claim any type
of perpetual motion, just that they can return *some* energy back to the
system to *lessen* the energy needed to propel the boat.

Stephen