Why do sailboats zigzag all over the place?

Question from Disgruntled Powerboater, Lake Norman, NC

-Disgruntled Powerboater, Lake Norman, North Carolina Sailboats can't sail directly into the wind. When a sailboat aims directly into the wind, it stops moving. This is called "irons." In order to move upwind, a sailboat must sail at an acute angle to the wind direction and "tack" back and forth in a zigzag manner. -Ed.