Inside overlap at the leeward mark
The situation
Two boats run down to the leeward mark on the same tack. As the first of them reaches the three-length zone, Green is the inside overlapped boat (closer to the mark) and Blue is outside.
The question
What must Blue give Green, and what if the overlap later breaks?
The ruling
Blue must give Green mark-room (rule 18.2(a)): room to sail to the mark and then to round or pass it on the required side. The overlap is locked in the moment the first boat reaches the zone — even if it later breaks, Blue still owes the mark-room. Green, for her part, must not take more room than her mark-room allows and must keep to the other rules while inside.
Inside overlap at the zone means mark-room, decided when the first boat reaches the zone — and it isn't lost if the overlap breaks.
Opens the situation on the boat-length grid — scrub it and see exactly how the boats meet. Free, no account needed.
Rules cited
See the underlying rule: Rule 18 — Mark-Room.
Related cases
- Clear ahead at the zone · Leeward Mark
Running down to the leeward mark, Green is clear ahead of Blue as the first of them reaches the three-length zone. Blue then lunges for the inside at the last second.
- Overlap obtained too late · Leeward Mark
Blue is clear astern as Green reaches the zone, then ranges up and gets an inside overlap once they're already inside the zone, and calls for room.
- The overlap breaks before the mark · Leeward Mark
Blue is the outside overlapped boat as they reach the zone, so she owes Green mark-room. Then Blue drops back and the overlap breaks before they get to the mark.
- “The overlap broke — so I shut the door” · Leeward Mark
Blue is the outside overlapped boat as the two reach the leeward-mark zone, so she owes Green mark-room. Coming in, Blue drops back, the overlap breaks, and Blue closes the door at the mark, sure she now owes nothing. The boats touch and Blue protests Green for forcing in.
Related guides
- Racing Rules of Sailing explained: a beginner's mental model
The Racing Rules of Sailing 2025-2028 keep boats apart and racing fair. Here's the mental model: right of way, keep clear, marks, the zone and penalties.
- What is mark-room? Rule 18 explained simply
Mark-room is the room an inside boat is owed to sail to and round a mark under rule 18. Learn the zone, who owes it, and the common reversals.