Land / Ice Sailing Explanation Required

[sami325]

Folks :

I am looking for a layman explanation of why the speeds attained by land / ice sailing vehicles approach 3-5 times the wind speed.

Thank you

Sami

 

[knobhead]

Short answer based on my limited sailing experience: The wind doesn't 'push' the sail as you might expect, (if it did, tacking would be impossible) what happens is it bends the sail into an aerofoil shape. So the speed you get relies less on the windspeed than the efficiency of the aerofoil shape that you create. The more effiecient the shape for a given wind speed, the faster you'll go. When you consider that you also havn't got any resistance from water displacement on a land vehicle, you can really get some speed up!