Practice self rescue techniques every now and then. It is surprising how many class IV boaters don't know how to self rescue these days. Many also lack aggressive swimming skills as well. They are a danger to themselves and others. When swimming with a boat and paddle, hang on to both in one hand and drag to swim while swimming with the rest of your body. It is important to stay upstream of the boat, the last thing you need is to get caught between a swamped boat and a rock. Set an appropriate ferry angle to make it easier to get to shore. If you are quickly approaching a strainer, push off the boat and swim away from the danger. When close to shore, toss the paddle like a javelin onto shore. You can also push the boat quickly in easier water and swim to catch up. This can be faster than towing. Here is an video that demonstrates the technique: Self Rescue.