You can use your boat's wind wash to disturb the air of a sailboat by tacking directly underneath them, and slightly ahead of their bow. This is the "lee bow zone", and is a great way to catapult yourself to a better position in the race. In order to lee bow someone, you must tack directly underneath them, as close as physically and legally possible. When you complete the tack, your boat should be very close to the competitor, and about a half of a boat length ahead of them.