Four submerged torpedo tubes were fitted with three torpedoes for each tube. Two Zeiss rangefinders were fitted on the conning towers and there was also a Barr & Stroud instrument, possibly for precise stationkeeping on the master ship when concentrating fire. Two Krylov stadimeters were situated in the lower level of the forward conning tower. These would provide data for the central artillery post to calculate with its imported Pollen Argo Mark V Clock, a mechanical fire-control computer, and then transmit the gun commands via the Geisler transmission system for the gun crew to follow. During the winter of 1915–1916 the Zeiss rangefinders were transferred to armored hoods on the rear of the fore and aft turrets and, at some point, Barr & Stroud rangefinders were added to the roofs of the middle turrets. received a Pollen rangefinder in the spring of 1916. The armor protection of the "Gangut"-class ships had to protect against two different threats as revealed during the Russo-Japanese War. Japanese high explosive shells had riddled the unarmored portions of Russian ships and had even sunk several ships with their heavy armor belts unpenetrated. The Russians decided that the entire side of the ship needed to be armored, even though this would limit the thickness of the main belt. They developed a system where the outer armor would break up or at least slow shells down and burst immediately behind the outer armor and an inboard armor bulkhead would stop the splinters and shell fragments from reaching the vitals. This system likely would have worked against the British armor-piercing shells that performed so badly at the Battle of Jutland, but would have failed against the improved shells introduced afterwards with their redesigned fuses. A related weakness was that the turrets and conning towers lacked the inboard splinter bulkhead even though they used armor thickness roughly equivalent to that of the main belt. The waterline belt, made of Krupp cemented armor (KCA), had a maximum thickness of , but tapered to about on its bottom edge. It was long and had a total height of , of which was above the design waterline and below. However, the ship's draft was almost deeper than intended, which meant that much less was above water. The remaining portion of the waterline was protected by plates. The upper belt, which protected the casemates, was 125 mm of KCA over the citadel and high. It thinned to a thickness of 75 millimeters forward of the citadel.