Naval historian N. J. M. Campbell assessed her as a considerably better fighting ship than the Imperator Aleksandr II class. Dvenadsat Apostolov had a pair of three-cylinder vertical triple-expansion steam engines built by the Baltic Works and had a total designed output of . Eight cylindrical boilers provided steam to the engines, which drove two screw propellers. During her sea trials in September 1894, the powerplant produced and a top speed of using forced draft; at normal draft the ship reached about . After her initial engine trials, the ship's funnels were raised by to improve their draft and to keep the superstructure clear of funnel gases. She carried of coal at full load that provided a range of at a speed of . Dvenadsat Apostolov had six Siemens dynamos with a total output of . Armament and protection The main armament of Dvenadsat Apostolov consisted of two pairs of 30-caliber Obukhov Model 1877 guns mounted in twin barbette mounts forward and aft. They had a maximum elevation of +15° and could depress to −5° and traverse 270°. 66 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 five minutes, but the loading machinery would not work if the ship was heeled more than 5°. The four 35-caliber Model 1877 guns were placed on pivot mounts in the central casemate. The sides of the hull were recessed to give them axial fire. They could traverse a total of 100°. Each gun had an arc of fire of 130°. The ship carried 130 rounds for each gun. They fired a shell that weighed with a muzzle velocity of . For defense against torpedo boats, the ship was fitted with a dozen Hotchkiss guns mounted in embrasures in the hull or superstructure. They fired a shell at a muzzle velocity of . Two 5-barrel Hotchkiss revolving cannon were mounted at the forward end of the superstructure and two others on the platform just abaft the second funnel. Six single-barrelled versions were fitted in the fighting top on the foremast and two were in small embrasures at the after end of the superstructure. The locations of the other two guns are unknown and they may have been intended to arm the ship's boats. Dvenadsat Apostolov carried six above-water torpedo tubes. One