CALL UMP 40          

Rule 11 On the Same Tack; Overlapped
Rule 17 On the Same Tack; Proper Course
Definitions Clear Astern and Clear Ahead; Overlap

Question 1
Yellow and Blue are sailing downwind with Yellow overlapped to windward of Blue. Rule 17 does not apply. Both boats are sailing well above what the umpires consider a proper course. Yellow is keeping clear. Green, a boat in another match, is sailing lower and slower than Blue and Yellow.
Yellow establishes an overlap on Green from clear astern. Because Yellow is between Green and Blue, all three boats now become overlapped. Blue continues to sail what the umpires consider to be above her proper course.
Green luffs to avoid Yellow and displays a Y-flag. What should the call be?

Answer 1
When the overlap is established (by Yellow) Blue is more than two of her hull lengths from Green and therefore has no proper course restriction. Yellow is sailing a proper course to keep clear of Blue. No rule is broken. Display the green and white flag.

Question 2
Would the answer be any different if only Yellow displayed a Y-flag?

Answer 2
No