Your best leebow defense
The basic defense is to tack away, get up to speed and tack back. Wait until the port boat has completed its tack underneath you, and then tack away. If you still want to go left, as you were before the encounter, then get to speed and tack back. Now you have a blocker to take care of any future leebow situations, and they cannot cross you. You're in control.

Remember also that just because you are the starboard boat, doesn’t mean you have to use your starboard tack rights. If you are bounding along, heading the way you want and happy to stay on your tack, the last thing you want is someone stealing your lane by leebowing you. Think ahead and make a plan. Just because you are on starboard tack doesn’t mean you are strong.

One possible option is to let the port boat cross, especially if they are close to crossing anyway. This works early in the leg when you are trying to escape the pack and sail your shift. Have the crewmember that’s most visible to them wave them across and call, “Okay,” or, “Go Ahead!” Do this early enough so they can process it, turning down at the same time making it clear they can cross. If you are close to the port-tack layline, there’s no need in letting them cross (thereby giving them control going into the mark), particularly if there are no other close competitors. But when you’re happy to keep going straight on the open course, it can work well to wave other boats across.

When the port-tack boat is in a weaker position, and therefore controllable, a defense against the leebow that often works is to sail a few degrees lower and build extra speed. Put the bow down a little with a small ease of the sails when you are 10 to 20 seconds away from getting leebowed. Your speed comes up, and the closing period shortens between the two boats, putting increased pressure to tack on the port boat. Be sure to hold a constant course as the boats gets close. When the other boat commits to its tack, trim back in to normal upwind settings and gently return to your upwind course. The extra speed developed can propel you to a position that leaves you unsusceptible to the effects of the leebow. If it doesn’t work, you can tack away with no real loss.

Leebowing from starboard tack
The trickiest leebow maneuver is tacking under a port-tack boat. The starboard boat has rights, but also responsibilities. The goal of this move is to get the port boat to commit to turning down to duck the starboard one, and then tack before it gets too close. The challenging part is to avoid fouling the port boat by tacking too close. As a starboard boat, remember that you can’t make any turns that leave the port boat with no option to avoid you. You also have to finish your tack before they have to avoid you as a new port tack boat yourself.

Generally, when you leebow a port-tack boat, you have to start your turn earlier, which can leave you uncomfortably far to leeward when you’re back up to full speed. So you should plan to allow more time to scrape off your opponent after the tack (presuming that’s your goal). Also remember to be full speed in and full speed out.

One of the very coolest moments in sailing is when, after a lee-bow, you realize that your opponent is not going to tack away immediately. This allows you the few seconds you need to get up to speed. As your opponent slows, and then tacks away, you can often match immediately, or a length later, and finish in a strong position abeam and to windward. If you listen carefully, you might even hear the last person who gets on the rail of the leeward boat say, “How’d they do that?”

Good luck. Have fun with this, and remember to keep those smiles of satisfaction to yourself so you’re not the next target.