Question 1
Before the start A and X, reaching on starboard tack, approach an anchored boat. When A reaches the two-length zone, she is clear ahead of X. A passes to windward of it, bears away alongside it, then gybes in order to sail around its stern. Very soon after A gybes, X is still on starboard and gains a small inside overlap. X changes course trying to avoid contact with A but there is contact. There is a protest. What should the call be?

Answer 1
Rule 18.2(c) requires X to keep clear until the boats have passed the obstruction, and she is not entitled to room to pass the obstruction if she becomes overlapped inside A. When A changes course and gybes towards the obstruction, she is subject to rule 16.1 (because rule 18.2(d) only applies at marks, not at obstructions), and must give X room to keep clear. X is able to keep clear by luffing but chooses not to, so breaks rule 18.2(c). Penalize X.

Question 3
If while keeping clear X gains the inside overlap within the two-length zone, and is sailing a parallel course to A, before A changes course and gybes, and if X is then unable to keep clear, what should the call be?.

Answer 3
X is keep clear boat throughout the passing (rule 18.2(c)). However, because the boats are passing an obstruction, A is subject to rule 16.1 even when she changes course to pass the obstruction, and must give X room to keep clear when she changes course. At position 3 A changes course and does not thereafter give X room to keep clear. A therefore breaks rule 16.1. Penalize A.