When a boat reaches the zone and she is clear ahead, any trailing boat is required thereafter give mark-room. When a trailing boat establishes an inside overlap, she must still give mark-room to the boat ahead to sail her proper course.
Question
Three boats B, X, and Y are approaching an off-wind mark to be left to starboard. The proper course after the mark is a broad reach on port tack. Rule 17 does not apply to B. When B reaches the zone, Y is clear astern. When Y is alongside the mark, B bears away and gybes to prevent Y from passing between her and the mark. Y touches B and the mark and protests. What should the call be?
Answer
Penalize B.
When B reaches the zone she is clear ahead of Y who is required thereafter give B mark-room. When Y establishes an inside overlap, she shall also give B room to sail her proper course. Y does so and does not break r18.2(b) or (c).
When B gybes she must initially give Y room to keep clear; she fails to do so and breaks rule 15. After position 4, B is not entitled to exoneration under rule 21(a) because she is no longer sailing her proper course or within the mark-room to which she is entitled. Y is exonerated under rule 21(a) for breaking rule 10 and under rule 21(b) because she was compelled to break rule 31.
When B gybes she must initially give Y room to keep clear; she fails to do so and breaks rule 15. After position 4, B is not entitled to exoneration under rule 21(a) because she is no longer sailing her proper course or within the mark-room to which she is entitled. Y is exonerated under rule 21(a) for breaking rule 10 and under rule 21(b) because she was compelled to break rule 31.