Question 1
B reaches the two-length zone of a port-hand windward mark on starboard tack clear ahead of X. A approaches on port and tacks inside the zone ahead of X. A reaches a close-hauled course and X has to bear away to avoid her because of the presence of B. As a result X passes the wrong side of the mark. X protests. What should the call be?

Answer 1
As B reached the zone clear ahead of X, X has to keep clear of B. After A’s tack X must keep clear of her too, and can only do so by passing the wrong side of the mark. A’s tack prevents X from passing the mark. A breaks Rule 18.3(a). Penalize A.

Question 2
The situation is the same except that A tacks slightly further to windward and X establishes a leeward overlap on A. The presence of B prevents A from giving X room, and X makes contact with A and the mark. X protests. What should the call be?

Answer 2
A tacks inside the zone and X is fetching the mark. When X establishes an inside overlap, A is required to give X room, and rule 15 does not apply to X. A fails to give X room and breaks rule 18.3(b). Penalize A.