During tournament play..when a round gets called for darkness and you have to mark your ball…how do the mowers go over the marks?
Since we would know about the coins on the greens we would find them before cutting.
When it is time to go over the marks we would replace the marks with plastic markers and press them into the greens below the height of cut. Since the markers are supposed to be placed directly behind the ball the extra depression would have no effect on the replaced ball and the regular growth and other foot traffic of subsequent play will render the location the same as the rest of the green.
We would also stage a spotter for the ball marker. An assistant or such would be watching as the mower travels over the ball mark to make sure it did not move. If by chance it would move the spotter would be able to replace it back in its location.
If we believe there would be a serious possibility where markers would be stolen or moved by intruding night-time traffic we would put a paint dot behind the ball marker. Not a preferred practice because of the possibility of distracting the golfer when play resumes.
An additional way is to double mark the ball. (The golfer can also do this.) One with a traditional plastic ball marker and just behind it place a golf tee embedded into the ground. This does two things 1) I reduces the possibility of losing the location. 2) If the mower would happen to pick up the ball marker the tee would most likely remain. If not (highly unlikely) the hole from the embedded tee would remain making it easy for the spotter to replace the marker.
Mark Novotny CGCS