17 ON THE SAME TACK; PROPER COURSE

17.1 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 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.

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.