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