Rule 15: Acquiring Right of Way
Rule 15 of the Racing Rules of Sailing 2025-2028 covers the moment right of way changes hands. A boat that gets right of way has to give the other boat room to keep clear at first, unless she got it because of what the other boat did. The boat that just lost her rights gets time to respond.
Right of way changes hands all the time: a boat overlaps to leeward from clear astern, or finishes a tack onto starboard. Each time, the new right-of-way boat cannot demand an instant response. She leaves room to keep clear: the space and time the other boat needs to respond promptly, in a seamanlike way.
The exception is when the other boat hands you your rights. If a boat on starboard tacks onto port across your bow, you got right of way from her tack, not your own action, and rule 15 does not bind you.
Rule 15 sets how fast new rights take effect. Rule 16 then limits how the right-of-way boat uses them when she changes course.
Sail it
A boat sails up from clear astern and overlaps you to leeward. Sail the windward boat: she now has right of way, and rule 15 gives you room to respond.
Questions
How much room does rule 15 give?
Room to keep clear: the space and time the other boat needs to respond promptly and in a seamanlike way. It is not open-ended. Once she has had that chance, she has to keep clear.
Does rule 15 apply after a tack?
Yes. A boat that tacks onto starboard ahead of a port-tacker, or to leeward of a starboard-tacker, gains rights by her own action. Once she is close-hauled she has to give the other boat room to keep clear.
Does a leeward boat coming from astern have to give room?
Yes. Overlapping to leeward from clear astern gives her right of way by her own action, so she gives the windward boat room to keep clear first. If the overlap began within two of her hull lengths, rule 17 also holds her to her proper course.
Paraphrased from rule 15 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.