On the Same Tack, Overlapped
Rule 11 - ON THE SAME TACK, OVERLAPPED
When boats are on the same tack and overlapped, a windward boat shall keep clear of a leeward boat.
A boat keeps clear of a right-of-way boat
(a) if the right-of-way boat can sail her course with no need to take avoiding action and,
(b) when the boats are overlapped, if the right-of-way boat can also change course in both directions without immediately making contact.
Leeward and Windward
A boat’s leeward side is the side that is or, when she is head to wind, was away from the wind.
However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side.
When two boats on the same tack overlap, the one on the leeward side of the other is the leeward boat. The other is the windward boat.
Tack, Starboard or Port
A boat is on the tack, starboard or port, corresponding to her windward side.
Clear Astern and Clear Ahead; Overlap
One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat’s hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern.
However, they also overlap when a boat between them overlaps both.
These terms always apply to boats on the same tack.
They apply to boats on opposite tacks only when rule 18 applies between them or when both boats are sailing more than ninety degrees from the true wind.
Examples: Windward (blue) must keep clear of Leeward (yellow)
Yellow (Leeward) is outpointing Blue (Windward)
Options for Blue (Windward):
Keep clear by tacking away from Yellow
Keep clear by luffing above close-hauled to then fall in behind Yellow.
Defending a passing lane
Yellow is approaching the Starting Line, with Blue to Windward.
Blue must keep clear of Yellow.
The presence of a Starting Line makes no difference in the application of this Rule.