Good input. And collisions will inevitably occur.
But better, further reaching wisdom is for each and every paddler to cultivate some ettiquette regarding spacing. I am lucky my whole face didn't explode like sam's did back in the late 90's while five of us were surfing alongside each other on a five boat wave. The Jack ass who hit me lost control of his boat and it charc'ed over toward me at a very high rate of speed and the bow (He was paddling a Mongoose, I think) was blunt enough to knock me hard in the cheekbone. Nothing broken, but based on how I felt I am surprised. Bruised up pretty good.
Seriously, boaters simply follow too close most of the time. Another time I was the offender, dropping in on Rob after he unexpectedly took a deep surf at Miracle Fabric on Robe. My fault though, I was following too close. He nailed my arm and it hurt for two weeks. But hey, I should have known better.
A really awesome creeker/raft guide I know was following me too close as I approached the Initiation boof on the Top Tye. I happened to find a pocket of slow water that killed my speed and shifted me to the right of where the Money Boof is. His boat plugged the drop, diving beneath mine. His mouth was bleeding and he ended up with an expensive dental bill. I felt horrible, on account that I botched my line, causing him to end up right on my tail as I plunged over the wrong part of the drop. But he was following way closer than necessary and therefore wasn't accounting for random, less ideal outcomes...
fu*kin Hawthorn boofed onto my chest once
In that manky little entrance slot above Gettin Busy. I got pinned, upside down, with my chest on a flat rock the size of your average coffee table, with my boat over top me. He should have waited till he saw me completely out of the channel, in the eddy below looking upstream at him before he even entered. Instead he boofed onto my hull, squashing my torso between my deck and the rock I was draped over. I can laugh about it now, and he is definitely a conscious individual whom I have a ton of respect for, but that sh*t knocked the wind out of me. Those are just the examples that come to mind.
Sorry to take the thread in a different direction, but the following too close is the issue. Avoiding these circumstances is why our parents (hopefully) raise us to be thinking, considerate critters. This sh*t is avoidable 90% of the time.
Mike does illustrate a certain level of awareness by sharing his experience though. My take is however that if a boater has those reflexes and awareness to begin w/ they should be able to avoid collisions. Once its occuring, though, and it will happen to all of us if we boat long enough, those insights are to be heard. Even in the split second before impact, choices can be made to minimize the damage.