Rule 12; On the Same Tack, Not Overlapped
Definitions; Clear Astern and Clear Ahead; Overlap
Whether one boat is clear astern of another or overlapped with her does not depend on the direction of either boat.
Question
In the pre-start, Blue and Yellow are both on the same tack with Yellow clear ahead. Both boats start moving astern and are still not overlapped.
Which boat has the right-of-way?
Answer
According to the definition Blue is clear astern and therefore required by rule 12 to keep clear.
Whether one boat is clear astern of another or overlapped with her does not depend on the direction of motion of either boat.