eroyd where was the incident? You mentioned a harbor, of which there are none in elk lake. If they hit your line they probably didn't even notice. Rowing shells cannot travel in shallow water due to a fin and in some boats a rudder. How close did they actually come to you?
Not accusing you of exaggerating but it would be nice to know where and how this happened exactly. That way if I am ever bowing a boat that gets into a similar situation I can take measures to avoid hitting you or your line.