What part of the starting mark is 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.
Interests in your thoughts.
12.3 J2.1(5)* [The starting line is between staffs displaying orange flags on the starting marks.][The starting line is between a staff displaying an orange flag on the [starting mark][signal vessel] at the starboard end and the course side of the port-end starting mark.][The starting line is .] See RRS Race Signals Orange flag
As such, it sounds like your text would be: The starting line is between a staff displaying an orange flag on the signal vessel at the starboard end and the course side of the port-end starting mark.
That would make your line the upwind side of the mark.
However, it makes no sense for tetrahedron buoys in choppy seas where the course side (the windward corner of the base of the tetrahedron) is not visible.
Nor does it make sense for any buoy distant from the line caller. In these cases, the midpoint (= the top) is a better target.
Define the line in your sailing instructions as you see fit!
On the course side is the operative wording. "The course side," in practice, is the part of the mark usually to windward the RO can see (or estimate at the start of an offshore race with 6' seas running), instantaneously at the starting gun/whistle. This is an eyeball, judgement call, sometimes made on a very unstable platform, in less than two seconds. If the RO, with her/his eyeball on the signal boat line flag staff, sees any portion of the mark at the gun, the boat is not on the course side. If the mark is covered by the bow, the boat is on the course side, "over the line." Don't blink.
It's why tetrahedrons - with a constantly changing course side / non-vertical aspect as they rotate - are less than ideal as starting marks. Cylinders or spheres ("tomatoes") are much better. An anchored boat with a flag/staff is the best - plus you have another set of eyes on the line.
As to whether tetrahedrons, cylinders, or flagstaffs are better, A tetrahedron, like a sphere, is very unlikely to pitch such that it moves its line. A cylinder or staff can readily lean out over its own footprint, which might be confusing. Especially if you run your races outside. In the wind.
Thank you.
Jerry