Y reaches the zone of a starboard-hand windward mark clear ahead of B and slightly above the layline. Both boats are on port tack. The next leg is a beam reach. Y stops with her bow 1½ lengths to windward of, and level with, the mark. B, on the port tack layline, tries to sail between Y and the mark. However, Y bears away below her proper course and there is no longer space for B to pass between Y and the mark. B makes contact with Y and the mark and protests. What should the call be?

Penalize Y.

When Y enters the zone she is clear ahead of B and is entitled to mark-room under rule 18.2(b). Mark-room includes room for Y to round the mark as necessary to sail her course and, when B becomes overlapped inside her, rule 18.2(c)(2) requires that B also gives Y room to sail her proper course. B does so and complies with rules 18.2(b) and (c).

After B becomes overlapped to leeward of Y, Y is required to keep clear. She fails to do so and breaks rule 11. She is not entitled to exoneration under rule 21(a) because she is not sailing her proper course or within the mark-room to which she is entitled.

B breaks rule 31 but was compelled to touch the mark as a consequence of Y’s breach of rule 11. Exonerate B under rule 64.1(a).