Typical of side wheel steamers, the Maple Leaf's engine room is located amidships between the paddle wheels. The machinery layout for a walking beam engine is generally standardized and found in many sources (Lardner 1848; Hawkins 1904; Ward 1860). Evidence from the site indicates the A-frame supporting the walking beam was located forward of the paddle shaft. It follows that the engine, including the condenser, air pump and hot well, was placed in front of the A-frame. A boiler is located on each side of the A-frame and extend aft under the paddle shaft. Fuel bunkers are probably forward near the deck hatch. The actual location of the engine room along the length of the hull is hard to determine. The aft edge of the engineering space is marked by the termination of deck planking at 121 feet. This position is further supported by the interior cargo hold excavation. The cargo space has been excavated to a point approximately 124 feet aft of the stem without encountering a bulkhead marking the end of the hold. The edge of the planking combined with the Maple Leaf's engine room length given in the 1851 Certificate of Ownership provides the most accurate means to locate the machinery spaces. The stated length of the engine room is 71.7 feet, placing the forward end of the room 49.3 feet aft of the stem or just behind the forward cargo hatch.
Results of the 1992 forward cargo hold excavation make this location suspect. Tent poles and other containers extended into the west (aft) wall far beyond a supposed bulkhead indicated by the engine room measurement. It is possible the bulkhead was damaged or destroyed by the torpedo explosion or later environmental processes. Any conclusions can only be determined after further excavations to examine this specific question.
The 1993 investigations in the engineering spaces located one boiler, the paddle shaft, the paddle shaft connecting rod and walking beam fragment, A-frame timbers, and fragments of the air pump. The engine is missing, including the engine cylinder, condenser, hot well and valve chest. Timbers and other debris fill all open spaces of the engine room restricting access to lower areas. This material was left in place limiting documentation to the intact deck and upper levels of the engine spaces. Each major component will be discussed separately.