Rules 14 through 17 make up section B of the Racing Rules called “General Limitations”. The idea is to apply some limitations to the Right of Way rules from Section A in order to close some loopholes and make everything more fun. One of the most important is Rule 17 which covers interactions between overlapped boats on the same tack.

When two boats are overlapped on the same tack the windward boat must keep clear of the leeward boat, but based on Rules 17.1 and 17.2, there are some significant limits on the course each boat can sail. Basically, Rule 17.1 says that a leeward boat that came from behind is limited to sailing no higher than its Proper Course. But if the windward boat came from behind, the leeward boat can sail as high as head to wind. Rule 17.2 limits the windward boat to sailing no lower than its proper course while near a leeward boat.

Let’s say you are sailing along and are catching a boat ahead. At some point you will have to choose to go below or above the other boat. If you go to windward, then the other boat can head up as much as they want to keep you from passing and you will have to stay out of the way. If you go to leeward, you become the right of way boat, but you are limited – you can’t sail higher than your “proper course”. On an upwind leg that means you can’t "luff up" the windward boat. But if your boat points higher than the one you are passing, you can still pinch them off so that they might have to tack to stay clear. On reaching and running legs, the limited leeward boat is not allowed to sail higher than they would have without the other boat there. A straight line to the next mark is a proper course, but you are allowed to sail higher than that if you have a good reason. It is important to note that it is the proper course of the leeward right of way boat that matters for Rule 17.1 and that the windward must change course to keep clear, even if it means sailing above their own best course.

Now let’s change boats and say that you are sailing along on a reach or run and a boat is catching you from behind. While you are still clear ahead, you are the right of way boat. If the other boat tries to sail to windward of you, Rule 17 doesn’t apply and you are not limited. However, if the boat coming up from behind is heading to leeward of you, once they get within two boat lengths (even before they are overlapped) you become limited by Rule 17.2 and you cannot sail below your proper course. Basically it means that you can’t head down to keep them from passing you, and once they become overlapped, you can’t sail down closer to them. Proper course again means the course you would sail if the other boat was not there. A course straight to the next mark is almost always proper, but you may legitimately sail lower if for example you are trying to go to leeward of some boats ahead. Just remember that once the passing boat gets a leeward overlap that they become right of way and you must keep clear even of you have to sail higher than your desired course.

That leaves one other big question for windward/leeward right of way situations: when can the leeward boat tack? If there aren’t any other boats or obstructions around, the simple answer is that the leeward cannot tack if there is a windward boat in the way. This is due to Rule 13. If Rule 17.1 does not limit the leeward boat, then they are free to head all the way up to head to wind and the windward boat must keep clear. However, once they pass head to wind, Rule 13 turns on and the tacking boat must keep clear of all others and they aren’t even entitled to “room to keep clear”. If they can’t clear the windward boat, they can’t tack. There is one fairly common exception that is covered by Rule 19. For example, on an upwind leg two port-tack boats are heading towards a starboard tack boat and the leeward boat won’t be able to cross safely ahead. In this case, the leeward gets to decide if they want to duck below the starboard boat or tack. If they choose to duck, they must give the windward boat room to duck as well. If they choose to tack they must hail the windward boat for “room to tack” and the windward boat must promptly tack or hail back “you tack” and then keep clear while the leeward boat tacks. It’s important to remember that “room to tack” only applies at obstructions such as a right of way boat or the shore. Just because the windward boat is sailing past the layline to the mark doesn’t give the leeward boat any right to tack. Likewise, another boat that is not right of way is also not an obstruction. A starboard tack leeward boat cannot hail a windward starboard tack boat for room to tack when approaching a port tack boat because the port tack boat is required to keep clear of both starboard boats.

At this point I want to recommend two books to fill in the many details too numerous to cover here. First, if you don’t have a copy of the “Racing Rules of Sailing”, go to the ussailing.org web site and order one. The language is fairly straightforward, and sometimes it’s just better to go straight to the source. Second is “Understanding the Racing Rules of Sailing Through 2004” by Dave Perry. He spends, for example, nine and a half pages covering Rule 17 in far more detail than I can possibly include here and the diagrams are great. As an added bonus, he includes the entire text of the official racing rules as an appendix, so it really is the only book you need.