12 to frame 74. It had a metacentric height of . They were considered to have good seagoing qualities, with a tactical diameter of and they could complete a full 360° circle in seven minutes and 32 seconds. Propulsion The Imperator Aleksandr II-class ships had two 3-cylinder vertical compound steam engines driving screw propellers. Twelve cylindrical boilers provided steam to the engines. The engines of the Imperator Aleksandr II were built by Baltic Works and had a total designed output of . On trials, the powerplant produced , and a top speed of . She carried of coal that provided a range of at a speed of and at a speed of . Imperator Nikolai Is engines were built by the Franco-Russian Works, but only had a designed output of . They were a disappointment on trials, only producing , and a top speed of . She carried of coal that gave her a range of at a speed of . Armament The main armament of the Imperator Aleksandr II-class ships was a pair of Obukhov Model 1877 30-caliber guns. Those in Imperator Aleksandr II were fitted in a twin barbette mount forward, but Imperator Nikolai Is guns were fitted in a turret. These guns had a maximum elevation of 15° and could depress 2° and could traverse 220°. 60 rounds per gun were carried. They fired a shell at a muzzle velocity of to a range of at an elevation of 6°. The rate of fire was one round every four to five minutes. The four Obukhov Model 1877 35-caliber guns were on center-pivot mounts in casemates at the corners of the citadel, the hull being recessed to increase their arcs of fire ahead or behind. The forward guns could traverse a total of 125°, including targets within about 4° of the centerline. The rear guns had an arc of fire of 105° and could fire on targets within about 10° of the centerline. These guns had a maximum elevation of 15° and could depress 5°. They were provided with 125 rounds per gun. They fired a 'light' shell that weighed or a 'heavy' shell that weighed . The muzzle velocity achieved depended on the shell weight and the type of propellant. A 'light' shell with brown powder reached while that same shell with smokeless powder achieved . In contrast a 'heavy' shell with brown powder could only be