On 14 Oct, 14:17, Andy Champ wrote:

An apparent wind from dead ahead can add nothing but a force directly
astern.

The case where a true wind from ahead can be used to drive a windmill
that can drive a propeller to propel the vessel is different; but this
requires a true wind.

Care to explain why a windmill which is capable of powering itself
forward against it's own drag can only do it with a true wind? How
does it know if the wind it is 'feeling' is true or not, it has no
concept of true wind which is merely the wind speed and direction at
an arbitary stationary point.

As far as the windmill is concerned it has a 20kt headwind and
(alledgedly) it can take that energy, use some of it to hold itself
stationary against the wind and _still_ have surplus energy to drive
forwards. If it can do that you could gear it to the engine of the
20kt powerboat and save petrol equivalent to the surplus power that is
left over once you subtract the energy required to overcome the
windmill's own drag from the total energy harnessed by the windmill.

"Andy Champ" wrote in message
news:j-idnSDiMoeUio_anZ2dnUVZ8q-
An apparent wind from dead ahead can add nothing but a force directly
astern.

The case where a true wind from ahead can be used to drive a windmill that
can drive a propeller to propel the vessel is different

I have such a vessel you can buy, she's called "Bhaskara's Wheel".

Andy Champ wrote:

BTW ice yachts cannot make 146mph *directly* upwind.

I didn't say they could, in fact close hauled at those speeds they are
usually sailing close to downwind, an apparent wind close to directly
ahead.

Nor in the case of the motorsailer will the apparent wind be from dead
ahead.

toad wrote:

On 14 Oct, 14:17, Andy Champ wrote:

An apparent wind from dead ahead can add nothing but a force directly
astern.

The case where a true wind from ahead can be used to drive a windmill
that can drive a propeller to propel the vessel is different; but this
requires a true wind.

Care to explain why a windmill which is capable of powering itself
forward against it's own drag can only do it with a true wind? How
does it know if the wind it is 'feeling' is true or not, it has no
concept of true wind which is merely the wind speed and direction at
an arbitary stationary point.

As far as the windmill is concerned it has a 20kt headwind and
(alledgedly) it can take that energy, use some of it to hold itself
stationary against the wind and _still_ have surplus energy to drive
forwards. If it can do that you could gear it to the engine of the
20kt powerboat and save petrol equivalent to the surplus power that is
left over once you subtract the energy required to overcome the
windmill's own drag from the total energy harnessed by the windmill.

MY recollection of this is that with a windmill it's simply not possible
to reduce the drag sufficiently to get a sufficient energy to make it
useful. Wingsails are much better at it or even even proeprly trimmed
sails.

ASCII news isn't the best medium to get the point across, but I'll try.

If one is motoring in a calm on a flat millpond then there is an
apparent wind equal to the speed of the boat from dead ahead. Hoist a
sail and you can make no use of that wind, agreed. However that only
applies if you maintain the same course. Now do what any sensible bloke
would do and adjust your course to make use of the wind as well as the
motor. You now have wind in your sails and you still have an apparent
wind. If you look at the force triangle there is still a component from
the apparent wind.

No doubt the craptain also doesn't beleive in back EMF or any of the
other phenomena which appear to produce "something from nothing" however
it's not the case that something is being produced from nothing and in
this case the extra energy is achieved at the usual expense of not being
able to sail directly into the apparent wind.

On 14 Oct, 15:16, (Steve Firth) wrote:

Nor in the case of the motorsailer will the apparent wind be from dead
ahead.

Oh yes it will!

On 14 Oct, 15:28, (Steve Firth) wrote:

If one is motoring in a calm on a flat millpond then there is an
apparent wind equal to the speed of the boat from dead ahead.

Yet you've just twice denied that to be the case:

"Nor in the case of the motorsailer will the apparent wind be from
dead
ahead."

"they're right and you don't understand physics. "

If you must troll pick a consistent line of argument.

On 14 Oct, 15:28, (Steve Firth) wrote:

If one is motoring in a calm on a flat millpond then there is an
apparent wind equal to the speed of the boat from dead ahead. Hoist a
sail and you can make no use of that wind, agreed. However that only
applies if you maintain the same course. Now do what any sensible bloke
would do and adjust your course to make use of the wind as well as the
motor.

Umm. What happens to the apparent wind from dead ahead when you turn
and make "dead ahead" a different direction?

Ian

On 14 Oct, 15:16, (Steve Firth) wrote:

Nor in the case of the motorsailer will the apparent wind be from dead
ahead.

It's flat calm. Where does the sideways component of the apparent wind
come from?

Ian

On 14 Oct, 16:12, Ian wrote:
On 14 Oct, 15:16, (Steve Firth) wrote:

Nor in the case of the motorsailer will the apparent wind be from dead
ahead.

It's flat calm. Where does the sideways component of the apparent wind
come from?

I fear that the Craptain has finally flipped and has created the Steve
Firth ID in order to argue with himself.

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