10 ON OPPOSITE TACKS
When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.
Animate!!

11 ON THE SAME TACK, OVERLAPPED
When boats are on the same tack and overlapped, a windward boat shall keep clear of a leeward boat.
Example #1 -- Animate!!
Example #2 -- Animate!!

12 ON THE SAME TACK, NOT OVERLAPPED
When boats are on the same tack and not overlapped, a boat clear astern shall keep clear of a boat clear ahead.
Animate!!

13 WHILE TACKING
After a boat passes head to wind, she shall keep clear of other boats until she is on a close hauled course. During that time rules 10 11 and 12 do not apply. If two boats are subject to this rule at the same time, the one on the other's port side shall keep clear.
Animate!!

14 AVOIDING CONTACT
A boat shall avoid contact with another boat if reasonably possible. however, a right-of-way boat or one entitled to room:

   (a) need not act to avoid contact until it is clear that the other boat is not keeping clear or giving room, and

   (b) shall not be penalized unless there is contact that causes damage.
Animate!!

15 ACQUIRING RIGHT OF WAY
When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat's actions.
Animate!!

16 CHANGING COURSE
When a right-of-way boat changes course, she shall give the other boat room to keep clear.
Animate!!

17 ON THE SAME TACK; PROPER COURSE
17.1 A boat that establishes a leeward overlap from clear astern within two of her hull lengths of a windward boat shall not sail above her proper course during that overlap while the boats are less than that distance apart, unless as a result she becomes clear astern.
Animate!!

17.2 Except on a beat to windward, while a boat is less than two of her hull lengths from a leeward boat or a boat clear astern steering a course to leeward of her, she shall not sail below her proper course unless she gybes.
Animate!!

18 PASSING MARKS AND OBSTRUCTIONS
18.1 When this rule applies

Rule 18 applies at a mark or obstruction to be left on the same side when boats are about to pass it until they have passed it. However, it does not apply:

   (a) at a starting mark or its anchor line surrounded by navigable water from the time the boats are approaching them to start until they have passed them,
  Animate!!

   or (b) between boats on opposite tacks when they are on a beat to windward or when the proper course for one of them to pass the mark or obstruction is to tack.
  Animate!!

18.2 Giving room; Keeping clear

  (a) When boats are overlapped before one of them reaches the two-length zone, if the outside boat has right of way she shall give the inside boat room to pass the mark or obstruction, or if the inside boat has right of way the outside boat shall keep clear. If they are still overlapped when one of them reaches the two-length zone, the outside boat's obligation continues even if the overlap is broken later. This rule does not apply if the outside boat is unable to give room when the overlap begins.
  Animate!!

  (b) If a boat is clear ahead when she reaches the two-length zone, the boat clear astern shall keep clear even if an overlap is established later. Rule 10 does not apply. If the boat clear ahead tacks, rule 13 applies and this rule no longer does.
  Animate!!

  (c) If there is reasonable doubt that a boat established or broke an overlap in time, it shall be presumed that she did not.
  Animate!!

18.3 Tacking

If two boats were on opposite tacks and one of them tacked within the two-length zone to pass a mark or obstruction, rule 18.2 does not apply. The boat that tacked:

  (a) shall not cause the other boat to sail above close-hauled to avoid her or prevent the other boat from passing the mark or obstruction, and
Animate!!

  (b) shall keep clear if the other boat becomes overlapped inside her, in which case rule 15 does not apply.
Animate!!

18.4 Gybing

When rule 18.2(a) applies and an inside overlapped right-of-way boat must gybe at the mark or obstruction to sail her proper course, she shall pass no farther from the mark or obstruction than needed to sail that course.
Animate!!

18.5 Passing a continuing obstruction

At a continuing obstruction, rule 18.2 is modified so that while boats are passing the obstruction an outside boat's obligation ends if the overlap is broken, and a boat clear astern may establish an inside overlap provided there is room at that time to pass between the other boat and the obstruction. If she does so, her obligation under rule 18.2(b) ends.
Animate!!

19 ROOM TO TACK AT AN OBSTRUCTION
19.1 When safety requires a close-hauled boat to make a substantial course change to avoid an obstruction and she intends to tack, but cannot tack and avoid another boat on the same tack, she shall hail for room to do so. Before tacking she shall give the hailed boat time to respond. The hailed boat shall either:

  (a) tack as soon as possible, in which case the hailing boat shall also tack as soon as possible, or
  Animate!!

  (b) immediately reply 'you tack', in which case the hailing boat shall immediately tack and the hailed boat shall give room, and rules 10 and 13 do not apply.
  Animate!!

19.2 Rule 19.1 does not apply at a starting mark or its anchor line surrounded by navigable water from the time boats are approaching them to start until they have passed them or at a mark that the hailed boat can fetch. When rule 19.1 applies, rule 18 does not.
  Animate!!

20 STARTING ERRORS; PENALTY TURNS; MOVING ASTERN
A boat sailing towards the pre-start side of the starting line or its extensions to comply with rule 29.1 or rule 30.1 shall keep clear of a boat not doing so until she is completely on the pre-start side. A boat making penalty turns shall keep clear of one that is not. A boat moving astern by backing a sail shall keep clear of one that is not.
  Animate!!

21 CAPSIZED, ANCHORED OR AGROUND; RESCUING
If possible, a boat shall avoid a boat that is capsized or has not regained control after capsizing, is anchored or aground, or is trying to help a person or vessel in danger. A boat is capsized when her masthead is in the water.
  Animate!!

22 INTERFERING WITH ANOTHER BOAT
22.1 If reasonably possible, a boat not racing shall not interfere with a boat that is racing.

22.2 A boat shall not deliberately interfere with a boat making penalty turns to delay her.

31 TOUCHING A MARK
31.1 While racing, a boat shall not touch a starting mark before starting, a mark that begins, bounds or ends the leg of the course on which she is sailing, or a finishing mark after finishing.
Animate!!

31.2 A boat that has broken rule 31.1 may, after getting well clear of otherboats as soon as possible, take a penalty by promptly making one complete 360 degree turn including on tack and one gybe. When a boat takes the penalty after touching a finishing mark, she shall return completely on the course side before finishing. However, if a boat has gained a significant advantage in the race or series by touching the mark she shall retire.

Abandon A race that a race committee or protest committee abandons is void but may be resailed.

Clear Astern and Clear Ahead; Overlap One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat's hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern or when a boat between them overlaps both. These terms do not apply to boats on opposite tacks unless rule 18 applies.

Finish A boat finishes when any part of her hull, or crew or equipment in normal position, crosses the finishing line in the direction of the course from the last mark either for the first time or, if she takes a penalty, after complying with rule 31.2 or rule 44.2.

Interested Party A person who may gain or lose as a result of a protest committee's decision, or who has a close personal interest in the decision.

Keep Clear One boat keeps clear of another if the other can sail her course with no need to take avoiding action and, when the boats are overlapped on the same tack, if the leeward boat could change course without immediately making contact with the windward boat.

Leeward and Windward A boat's leeward side is the side that is or, when she is head to wind, was away from the wind. However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side. When two boats on the same tack overlap, the one on the leeward side of the other is the leeward boat. The other is the windward boat.

Mark An object the sailing instructions require a boat to pass on a specified side, excluding its anchor line and objects attached temporarily or accidentally.

Obstruction An object that a boat could not pass without changing course substantially, if she were sailing directly towards it and one of her hull lengths from it. An object that can be safely passed on only one side and an area so designated by the sailing instructions are also obstructions. However, a boat racing is not an obstruction to other boats unless they are required to keep clear of her or give her room.

Overlap See Clear Astern and Clear Ahead; Overlap.

Party A party to a hearing: a protestor; a protestee; a boat requesting redress; any other boat or a competitor liable to be penalized, including under rule 69.1; a race committee in a hearing under rule 62.1(a).

Postpone A postponed race is delayed before its scheduled start but may be started or abandoned later.

Proper Course A course a boat would sail to finish as soon as possible in the absence of the other boats referred to in the rule using the term. A boat has no proper course before her starting signal.

Protest An allegation by a boat, a race committee or a protest committee that a boat has broken a rule.

Racing A boat is racing from her preparatory signal until she finishes and clears the finishing line and marks or retires, or until the race committee signals a general recall, postponement, or abandonment.

Room The space a boat needs in the existing conditions while manuevering promptly in a seamanlike way.

Rule (a) The rules in this book, including the Definitions, Race Signals, Introduction, preambles, and the rules of an appendix when it applies, but not titles;
      (b) the prescriptions of a national authority, when they apply;
      (c) the sailing instructions;
      (d) the class rules except any that conflict with the rules in this book;
      (e) any other documents governing the event.

Start A boat starts when after her starting signal any part of her hull, crew or equipment first crosses the starting line and she has complied with rule 29.1 and rule 30.1 if it applies.

Tack, Starboard or Port A boat is on the tack, starboard or port, corresponding to her windward side.

Two-Length Zone The area around a mark or obstruction within a distance of two hull lengths of the boat nearer to it.

Windward See Leeward and Windward.