CALL MR 37              

Rule 11 On the same tack, Overlapped
Rule 18.2(a) Giving Mark-Room
Rule 21.2 Taking Penalties

Question
Yellow, ahead of Blue, is taking a penalty around the finishing mark. As Yellow tacks and bears away on port, Blue, approaching the mark on starboard, bears away and gybes to port. There is a Y flag. What should the call be?

Answer
When Yellow passes head to wind, she begins taking a penalty and must keep clear under rule 21.2 until she completes her penalty by bearing away to a downwind course. In addition, rule 18.2(a) applies, since the boats are overlapped and in the zone. An alteration of course by Blue may be either to keep clear of Yellow, or to give Yellow mark-room, or both.
If Blue is required to alter course before Yellow completes her penalty, Yellow is not keeping clear under rule 21.2 even if Blue is altering course to give markroom.
Signal that Yellow has completed her penalty and penalize Yellow again for breaking rule 21.2. See Call MR 28.
If Blue’s alteration of course is not required until after Yellow completes her penalty, display the green and white flag.