When can I stop a race or order a re-row?

The Race Umpire ensures the proper conduct of the race and the safety of rowers (rule 11.15). If necessary, the Race Umpire may:

• stop the race (red flag waved and an audible signal, rule 10.10.5), impose any necessary penalties, and order the race re-rowed from the start, either immediately or later. For a later re-row, the Race Umpire and Starter decide the new start time in consultation with the Chief Umpire, and inform the crews concerned;
• let the race continue and exclude crews after it has finished;
• confine a re-row to the crews the Race Umpire designates, considering the crews' relative placings and any relevant progressions;
• decline to order a re-row if the effect of the impediment is immaterial to the order of finish or the progression of crews.

If a crew has been materially impeded, its chance of winning or progressing must be fully restored. Once the race has started, the Starter and the Judge at the Start are subordinate to the Race Umpire (rule 11.16).