Question 1
Approaching a starboard-hand windward mark on starboard tack, X is clear ahead of A at the two-length zone. X slows and A becomes overlapped outside her. X then luffs to tack round the mark, passes through head to wind, and her stern swing causes contact with A. X protests. What should the call be?

Answer 1
X reaches the zone clear ahead, so A becomes keep clear boat until X passes head to wind. In addition, when A becomes overlapped on the outside, she must give X room to round the mark. This includes room to tack, as tacking is a normal part of the manoeuvre of rounding the mark. Penalize A, and exonerate X under rule 64.1(b).

Question 2
Same situation as question 1, except this time A remains directly behind X. X luffs to tack, but as her stern draws level with the mark, A hails 'Don’t tack in my water' and prevents X from tacking round the mark. X protests. What should the call be?

Answer 2
When X reaches the two-length zone clear ahead, A becomes keep clear boat until both boats have passed the mark, or until X passes head to wind, when rule 18.2(c) ceases to apply and rule 13 applies instead. A can therefore change course while X remains on starboard tack, but X cannot pass head to wind unless she can do so and still keep clear of A. No penalty.

Question 3
Same situation as question 1, except this time A is further astern, and slightly to windward of X. X luffs and tacks. A luffs to round the mark, and as a result A makes contact with X while A is still on starboard tack. X protests. What should the call be?

Answer 3
When X passes head to wind, 18.2(c) ceases to apply. The boats become on opposite tacks on a beat and therefore no part of rule 18 applies. A becomes right of way boat subject to rule 16. Provided X would have kept clear of A if A had not changed course after X passed head to wind, then A fails to give X room to keep clear and breaks rule 16.1. Penalize A.