June 21, 1955. Sam Gray, David Rutford, and Fred Hallberg begin their cruise down the Mississippi River from Saint Paul Minnesota on a homemade raft. The raft was built of barrels and planks. Power for the propeller was provided by a 1939 Chevrolet they had paid $ 15 for. the car had 172,000 miles on it. The rear wheels of the car ran against another set of wheels which turned the propeller. The car's steering wheel turned the raft's rudder.