Rule C2.6 Tacking at a Mark
Question
Yellow tacks within the two-length zone and Blue becomes overlapped on the inside.
The umpires are not certain Blue could avoid becoming overlapped by luffing.
Yellow displays a Y flag. What should the call be?
Answer
Green and white flag. When the umpires are not certain that Blue could avoid
becoming overlapped by luffing, they shall presume that she could not.