As I'm sure we all know, that when you go sailing your fastest speed isn't directly downwind but when you are traveling at an angle to it. This allows sailboats and iceboats to go several times faster than the wind speed that is powering them. But how is it that a vehicle such as http://www.boingboing.net/2007/02/06/video-can-a-vehicle-.html", that is powered by the wind, can go DIRECTLY downwind faster than the wind that is powering it? Apparently, this is true of iceboats as well. Could someone please explain this so me.