They were just plain wrong, especially since they did it twice. They should've either fished behind you or asked you where you were planning on fishing so they would'nt get in your way. The distance thing depends on how crowded the area is, but the 100 yards Redge mentioned would be the minimum. Some people are just inconsiderate... I've been bass fishing before and had someone cast across the bow of my boat as they pulled in front of me.