A cart, wagon, boat, or ship moves as you command. The vehicle can be no larger than 10 feet long + 2 feet long per level (a 10th-level sorcerer can steer a 30- foot-long vessel). The craft must have its normal means of locomotion . You do not need to concentrate to maintain this effect, so you could cast it on a horse-drawn wagon, command it to “go straight,” and take your eyes off the road. The horse will pull the wagon straight until you tell it otherwise or the spell’s duration ends. The spell does not imbue a craft (or the animals pulling it) with intelligence. It cannot avoid obstacles that you do not tell it to avoid. Nor can it follow a command that requires intelligence, such as, “Sail to the port city of Andrecon” or even, “Follow the road.” Only simple instructions work, such as “straight,” “left,” “right,” and so on.