CALL UMP 28              

Rule 15 Acquiring Right of Way
Rule 17 On the Same Tack; Proper Course

Question
On a downwind course Yellow establishes an overlap to windward of Blue with her spinnaker. Yellow bears away, without breaking the overlap, and overlaps to leeward.
Do rules 15 and 17 apply?

Answer
Yes. At the moment Yellow becomes right of way as the leeward boat, rules 15 and 17 begin to apply.