The established course may be shortened at the discretion of the Race Committee. If the lead boat has not crossed the finish line by a designated time (generally an hour), the race may be abandoned. Any boat not completing the race within thirty minutes of the first boat to cross the finish line shall be scored DNF (did not finish).

The course may be shortened by the Race Committee at any turning mark of the course. However, this must be done before any of the boats reach the mark. Three sound signals shall be given to alert the skippers of the changed location of the finish line.