18.2 Giving Room; Keeping Clear
(a) overlapped - basic rule
When boats are overlapped the outside boat shall give the inside boat room to round or pass the mark or obstruction, and if the inside boat has right of way the outside boat shall also keep clear. Other parts of rule 18 contain exceptions to this rule.
(b) overlapped at the zone
If boats were overlapped before either of them reached the two-length zone and the overlap is broken after one of them has reached it, the boat that was on the outside shall continue to give the other boat room. If the outside boat becomes clear astern or overlapped inside the other boat, she is not entitled to room and shall keep clear.
(c) not overlapped at the zone
If a boat was clear ahead at the time she reached the two-length zone, the boat clear astern shall thereafter keep clear. If the boat clear astern becomes overlapped outside the other boat, she shall also give the inside boat room. If the boat clear astern becomes overlapped inside the other boat, she is not
entitled to room. If the boat that was clear ahead passes head to wind, rule 18.2(c) no longer applies and remains inapplicable.
(d) changing course to round or pass
When after the starting signal rule 18 applies between two boats and the right-of-way boat is changing course to round or pass a mark, rule 16 does not apply between her and the other boat.
(e) overlap rights
If there is reasonable doubt that a boat obtained or broke an overlap in time, it shall be presumed that she did not. If the outside boat is unable to give room when an overlap begins, rules 18.2(a) and 18.2(b) do not apply.