Here's the scenario:
Conditions: Very light wind, almost non existent. Evening wind dying.
Situation: Club evening can racing. Two boats are approaching the finish line at a fraction of a knot, Boat A clear ahead of Boat B whose bow is only inches from the stern of Boat A.
Event: Boat A gets a horn as her bow crosses the finish line and she immediately starts her engine and aggressively powers away. The wash from her prop brings Boat B to a compete stop and with insufficient wind makes no further headway.
Question: Were any rules broken?