 Key elements of sailing a ship are setting the right amount of sail to generate maximum power without endangering the ship, adjusting the sails to the wind direction on the course sailed, and changing tack to bring the wind from one side of the vessel to the other.A sailing ship crew manages the running rigging of each square sail.Each sail has two sheets that control its lower corners, two braces that control the angle of the yard, two clewlines, four buntlines and two reef tackles.