CALL UMP 22              

Rule 18.1, Passing Marks and Obstructions: When This Rule Applies
Rule 18.2(c), Passing Marks and Obstructions: Giving Room; Keeping Clear

Question 1
Blue and Yellow approach the windward mark on port tack with Blue clear ahead at the zone. The mark is to be rounded to starboard. Blue immediately gybes onto starboard tack. There is a Y flag. What should the call be?

Answer 1
Rule 18.2(c) requires Yellow to keep clear. Under rule 18.1, this requirement continues to apply 'until they have passed' the mark. Display the green and white flag.

Question 2
How far past the mark may Blue sail, gybe and remain protected?

Answer 2
As long as Yellow is still passing the mark, 18.2(c) continues to apply and Blue remains protected. The use of 'boats' and 'they' (plural) in rule 18.1 means that rule 18 continues to apply until both boats have passed the mark.