 Missouri was 183 feet (55.8 m) long overall, had a beam of 53 feet 8 inches (16.4 m) and a draft of 8 feet 6 inches (2.6 m). Her casemate extended for most of the length of the ship and was 130 feet 6 inches (39.8 m) long. It partially enclosed her 22-foot-6-inch (6.9 m) diameter center paddle wheel in a recess at the aft end of the casemate; the upper 8 feet 4 inches (2.5 m) of the paddle wheel protruded above the casemate and was totally unprotected. The stern wheel was powered by two steam engines taken from the steamboat Grand Era; four boilers provided steam to the engines and were connected to a single funnel. The ship had a maximum speed of 6 miles per hour (5.2 kn).
