Understood. Boat 1 had to tack when they did. When boat 1 started their tack boat 3 was under no obligations to also tack. The wind changed before the boats were on to port tack and under the new wind direction the position of the boats would have been such that boat 3 would have been in the line of obligation to provide room. This is unless a starboard boat can force the port boat to immediately tack back into a no water or almost no water situation, because there was not room to pull off a safe duck.