Rule 12: Clear Astern Keeps Clear of Clear Ahead
Rule 12 of the Racing Rules of Sailing 2025-2028 covers two boats on the same tack that are not overlapped. The boat clear astern keeps clear of the boat clear ahead. Catching up gives the boat behind no rights until she overlaps, and then rule 11 takes over.
A boat is clear astern when she is entirely behind a line square across the stern of the boat ahead. The boat ahead sails her own course. The boat behind picks the side she will pass on, early, and leaves room.
The moment the boat behind gets her bow past that line, they overlap and rule 12 stops. Pass to leeward and you become the right-of-way boat under rule 11, though rule 15 makes you give the other boat room to keep clear at first. Pass to windward and you are the windward boat, keeping clear under rule 11 instead.
Upwind, the boat behind is often sailing in the dirty air of the boat ahead, which is why most boats tack or foot off to pass rather than sail up her stern.
Sail it
A faster boat catches a slower one ahead on the same tack. Sail the boat behind and keep clear as you overtake.
Questions
Who has right of way when overtaking a sailboat?
The boat ahead, while the overtaking boat is clear astern (rule 12). Once they overlap, rule 11 decides it: the windward boat keeps clear.
Does the boat ahead have to hold her course?
No. She can change course, but because she holds right of way, rule 16 makes her leave the boat behind room to keep clear when she does.
Does rule 12 apply between boats on opposite tacks?
No. Rule 12 is only for boats on the same tack. On opposite tacks rule 10 applies, and port keeps clear of starboard whichever boat is ahead.
Paraphrased from rule 12 of the Racing Rules of Sailing 2025-2028, not quoted. The rule text is World Sailing's, and the rulebook is what a protest hearing reads.