I have fished, along with many others, in the Chattahoochee River, which is mostly a slow moving rivers, with a few small rapids for several years from float tubes. I have fished from doughnut tubes and currently use a Fishcat, which is near the top of the tube design in my opinion. I have been upside down in both types, only once because of water movement. Other than the loss of a couple of fishing rods and the drowning of electronics (cell phones & cameras) no permanent damage done. If money is no object check out the Scadden line of float tubes. For around $200 a Fishcat 4 is the way to go. Get a comfortable PFD and wear it.