Getting a rope and keeping it handy is part of becoming a responsible whitewater paddler. You obviously need to practice throwing it, but most self/assisted/swiftwater rescue classes are going to give you a lot of opportunity. Or go to any easy popular Class III drop with easy access and pull people out all day (Nantahala Falls for example).
Always talk to the victim before you offer yourself or your boat. If they cannot comprehend and follow directions, stay back and let them come to their senses or drown (once they drown, they are easier to deal with than a panicked swimmer).
Rescue people first, but evaluate them before you get close. If they are purely freaking out, they will try to stand on your head. The worst rescuers are those who act to fast in many situations... Never put yourself in serious danger to rescue someone who is floating along without a vest in an obvious panic.
Look them in the eyes, talk to them. If they can't follow instructions and converse with you, do not let them get to you. If they do, I was taught to dive deep and push off of them with my legs -- very effective at serparating them from you if you are both in the water, but swimming out to them is a last resort. Even then a live-bait type rescue is preferred (rope attached to a rescue vest so others can haul you in from shore).
Some rescues require immediate action, but not generally in a pool after a rapid. If a non-swimmer has no vest on going through a Class II and almost dies, I'm going to let him go before I put myself too much at risk. Throw him a rope, sure. Let him have the front of my boat -- only if he can talk and listen to me. Swim out to him -- no. I'd go get him after he stops thrashing around and then administer CPR before I let him grab me and try to drown me.
Full Size Sail Rig
Recreational Kayak Paddle
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