Port-Tack Layline at the Windward Mark
Rule 18 does not apply between boats on opposite tacks on a beat — a port-tack boat at the windward mark gets no mark-room and must keep clear.
Rule 18 (mark-room) does not apply between boats on opposite tacks on a beat to windward (rule 18.1(a)(1)). So a boat approaching the windward mark on the port-tack layline gets no mark-room from a starboard-tack boat — it's a straight port/starboard situation under rule 10. The port boat must keep clear by ducking or tacking; she can't demand inside room.
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How it interacts with other rules
- Rule 10 — On Opposite Tacks · see also
With rule 18 off, the port-tack boat simply keeps clear of starboard.
- Rule 18 — Mark-Room at a Windward Mark · see also
Between same-tack boats, mark-room does apply at the windward mark.