Question of the week:
The Red boat entered the zone clear ahead of Yellow boat. After rounding the mark, Red boat attempts to tack. Can Red boat tack in the zone or must she wait until she is out of the zone?

Answer: It depends
Red boat entered the zone clear ahead, Rule 18.2b requires Yellow boat to give Red boat Mark-Room.
Mark-Room does not include room to tack for a boat clear ahead. When Red passed head-to-wind, Rule 13 required her to stay clear of the Port tack Yellow boat as Yellow boat becomes the ROW boat. When a clear ahead boat passes Head to Wind inside the zone, Rule 18.2c turns off Mark-Room for that boat under Rule 18.2b. Until Red boat is ON a close hauled course, she cannot cause Yellow boat to alter her course to avoid her she must keep clear of Yellow boat as that would break rule 13. The word ON in Rule 13 does not mean that the boom on Red boat has passed to the port side of the boat. Red boat can be on a close hauled course even if her sails are luffing. A close hauled course would be a course the boat would sail with her sails close hauled to windward. If the wind was light, she could still be on a close hauled course with luffing sails and bearly moving.
After Red boat is ON a Starboard close hauled course and now the ROW boat again, she is required by Rule 15 to provide room and opportunity at that point for Yellow boat to keep clear of her. Yellow boat does not have an obligation to anticipate Red boat tacking in front of her and as the ROW boat, while Red is tacking, Red must stay clear of Yellow and not force Yellow boat to alter course to avoid Red boat. This situation with a clear ahead boat on a beat to windward does not change outside the zone. When the clear ahead boat passes head to wind, she is no longer the ROW boat and Rule 13 applies. A clear ahead boat tacking can cause several Section A rules to change. Rule 12 (Clear Ahead), Rule 13 (Tacking), Rule 10 (Opposite Tack), can happen very quickly!
18.2 Giving Mark-Room
(a) When boats are overlapped the outside boat shall give the inside boat mark-room, unless rule 18.2(b) applies.
(b) If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room.
(c) When a boat is required to give mark-room by rule 18.2(b), she shall continue to do so even if later an overlap is broken or a new overlap begins. However, if the boat entitled to mark-room passes head to wind or leaves the zone, rule 18.2(b) ceases to apply.
(d) If there is reasonable doubt that a boat obtained or broke an overlap in time, it shall be presumed that she did not.
(e) If a boat obtained an inside overlap from clear astern and, from the time the overlap began, the outside boat has been unable to give mark-room, she is not required to give it.
13 WHILE TACKING
After a boat passes head to wind, she shall keep clear of other boats until she is on a close-hauled course. During that time rules 10, 11 and 12 do not apply. If two boats are subject to this rule at the same time, the one on the other’s port side or the one astern shall keep clear.
Mark-Room
Room for a boat to sail to the mark, and then room to sail her proper course while at the mark. However, mark- room does not include room to tack unless the boat is overlapped to windward and on the inside of the boat required to give mark-room.





