The Corps of Discovery's keelboat was specially constructed for Lewis and Clark in Pittsburgh in 1803. Essentially, it was a 55-foot barge filled with supplies underneath the deck and along the sides. It needed a crew of 22. It was roughly half the size of the Pirate ship inside the Tampa Bay Buccaneers stadium, and very rarely shot footballs to Native Americans on the riverbank.
The Corps also took two smaller, but still rather substantial, boats that they called pirogues (similar to the boat you see in the painting of Washington crossing the Delaware). They took the keelboat as far as Fort Mandan in North Dakota, then sent it back down-river in the spring of 1805, when they proceeded on to the rougher portion of the Missouri.
There is a half-replica of the keel boat at Camp River Dubuis outside of St. Louis that shows how the boat was packed. There normally is a full replica at St. Charles as well, but that is the one being used this summer by the re-creation crew.
The best replicas, however, are two versions at Lewis and Clark State Park near Onawa, Iowa, on I-29. They are so splendid it's almost worth driving to the Iowa-Nebraska border just to see them.
I do not have any sort of water vessel on my journey. I have only a 2003 Chevy Malibu. But it can easily do 90 miles an hour (as far as I've pushed it so far, but I haven't reached Montana yet) and very rarely needs to be towed by rope (at least so far -- cross fingers).