If a boat clear astern becomes overlapped within two of her hull lengths to leeward of a boat on the same tack, she shall not sail above her proper course while they remain on the same tack and overlapped within that distance, unless in doing so she promptly sails astern of the other boat. This rule does not apply if the overlap begins while the windward boat is required by rule 13 to keep clear.
Luffing rights (ie the right to force a windward boat head to wind):
(i) a leeward boat has luffing rights before the start signal;
(ii) a leeward boat also has luffing rights after the start signal EXCEPT where the overlap is established from clear astern closer than two boat lengths away from the windward boat in any direction.
Note, a leeward boat has luffing rights when the overlap was established due to a tack by either boat (but not when the leeward boat tacked under the windward boat inside the zone).