On 28/09/2010 8:40 a.m., Andy Champ wrote:
On 27/09/2010 10:12, The Natural Philosopher wrote:

There was one interesting idea that was mooted, that on analysis I
couldn't find a flaw with: A wind powered boat or vehicle that could
sail or drive directly into the wind using a turbine facing the wind to
drive a water prop or wheels..also said to be capable of going faster
than the wind..directly downwind..less sure about that, though.



You can go as fast as you like in any direction, provided you have one thing
moving against another that you can extract energy from.

Typically this is the wind blowing over the water, or the land.

There is no theoretical speed limit; it's just the faster you go the more the
efficiency of your aerofoils / hydrofoils / wheels matters.

Andy

OK, Einstein, when you are travelling at the same speed as the wind, in the
direction of the wind, what "thing is moving against another", except for the
vessel moving against the water, which creates drag?