When my partner and I fish a river, which is rare, we usually don't know the holes that hold fish. We may see someone catching fish, so we'll try that same spot. If he is drifting, we will get in line 50 yards or so above him and let him drift through first. Sometimes it is ring-around -the-rosie with several boats drifting through, and then cruising up to the top of the hole to start drifting again. Kinda' like a dosey-doe. The thing we try to do is see how far they are casting and try to stay up stream twice that amount. There is really no excuse to snag someone else's line on a river unless you are just too close. If someone gets annoyed at us, depending on their tone and attitude we will either leave them to fish the hole or remind them that it is a public river and they don't own it and they can simply plant a juicy one where the sun don't shine! No one owns the river, nor should anyone act as they do no matter what they are fishing in. I give plenty of way to smaller boats and drifters because I realise they can't get out of my way near as easy as I can get out of theirs.