Defining the start line with start marks

The racing rules allows for fair competition, but it is a challenge to understand every scenario. To help facilitate the process, the Racing Rules of Sailing Forum offers an opportunity for experts to voice opinion. In a post by Doug Ryan, he was asking what part of the starting mark was the official end of the starting line:

We have a round ball as a starting “pin”. Looking down the line from the pre-start side of the RC flag staff, a boat had its bow directly in line with the center of the “pin” ball.

Is she OCS because she was over the line to the pre-start side of the ball? Starting clear because half the ball was still visible when the start horn/flag was sounded/dropped? Does the RC need to sight to the middle of the ball which is the hardest position to actually determine?

Curious as I have not faced this situation before. We can find nothing in RRS on this and there are no appeals we can find as OCS is not something you can protest. Interested in your thoughts…

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