the high speed of the Iowa class, or maintain the 27-to-28-knot speed of the North Carolina and South Dakota classes, the lower speed was chosen in order to rein in size and displacement. Design study of the BB-65-8 scheme for a 33-knot battleship resulted in a standard displacement of over , a waterline length of , and a requirement of ; by returning the BB-65 design to the slower maximum speed, the standard displacement and waterline length of the ships could be reduced to a more practical and , respectively, as exemplified by the BB65-5 scheme. In practice, the 27-to-28-knot speed would have still been enough to escort and defend the Pacific-based Allied fast aircraft carrier task forces, although the Montanas ability in this regard would be considerably more limited compared to the Iowas as the latter could keep up with fleet carriers at full speed. In September 1940, the 58,000-ton BB65-5A preliminary design scheme with a powerplant, the same as the one on Iowa class, was refined and subsequently named BB-67-1 after hull numbers BB-65 and 66 were reallocated as Iowa-class ships Illinois and Kentucky. Waterline length was reduced from for BB65-5 to for BB65-5A and then increased to for BB67-1. By January 1941, the design limit for the 58,000-ton battleship plan had been reached, and consensus among those designing the battleship class was to increase the displacement to a nominal to support the desired armor and weaponry on the ships. At the same time, upon discovering that the propulsion plant was more powerful than needed, planners decided to reduce output from 212,000 shaft horsepower in BB67-2 to in BB67-3 for a better machinery arrangement and improved internal subdivisions. The secondary armament battery of ten two-gun turrets was also changed to mount the /54 cal guns instead of the 5-inch/38 cal guns used on the Iowas. The number of 40-mm Bofors anti-aircraft gun mounts also increased, while protection of the propulsion shafts changed from the extension of the belt and deck armor aft of the citadel to armored tubes in an effort to control weight growth. By 1942, the Montana class design was further revised to BB-67-4. The armored freeboard was increased by , while the propulsion plant had its power reduced again to ; the standard displacement became and full load displacement was . Aesthetically, the net design for the Montana class somewhat resembled the Iowa class since