We know, we know. It sounds too much like the little yellow ducky you had as a kid or the blow-up doll you got your boss for his retirement party. All are watercraft that must be filled with air before they float. The first step is deciding what you need the boat to do. Answer these questions and you're well on your way to picking your craft.
Rafts are a configuration of tube chambers and a floor.
Catarafts consist of two tubes attached with a frame between them, and are popular among river runners, safety boaters, and fishermen. Because they don't have a floor, they're lighter and more maneuverable than conventional rafts. They can also carry a substantial amount of gear but are more cumbersome for carrying people. You can get a good deal and a good fit by buying a frame from the dealer where you purchase your boat. Most raft builders offer rowing frames designed around specific-sized tubes.