If a boat passes head to wind from port to starboard tack in
the zone of a mark to be left to port, rule
18.2 does not apply between her and another boat on starboard tack that
is then fetching the mark. If the
other
boat has been on starboard tack since entering the zone, the boat that passed
head to wind
(a) shall not cause the other boat to sail above close-hauled to avoid contact,
and
(b) shall give mark-room if the
other boat becomes overlapped inside her.