1) While sailboats must tack to go upwind, they can tack[1] downwind also. 2) Hull speed is a limitation for displacement sailboats. Sailboats that plane or us

1) While sailboats must tack to go upwind, they can tack[1] downwind also. 2) Hull speed is a limitation for displacement sailboats. Sailboats that plane or use hydrofoils or have long skinny hulls (e.g. catamarans) do not have the hull speed limitation of a displacement hull. While the article uses sailboats as their sailing example, a much better example would be iceboats[2] which have extremely low friction. They can go up to 10x the speed of the wind. According to google, the record is 143MPH. Iceboat racers definitely tack downwind and definitely go faster than the wind by jibing ("tacking") downwind. The key to understanding the "faster than the wind" car is to realize that, because the propeller is spinning, the apparent wind for the propeller is no longer coming from directly behind the car. The propeller is cutting across the wind and thus the apparent wind is coming at an angle "across the car". (Since the propeller is spinning in a circle, it never has to jibe - iceboats have to jibe because otherwise they would run out of ice.) [1] Technically sailboats will jibe rather than tack downwind. Tacking is when you pivot the bow into the wind, jibing is when you pivot the bow away from the wind. [2] https://en.wikipedia.org/wiki/Iceboat https://en.wikipedia.org/wiki/Iceboat