USSR
The Russian battleship Oktyabrskaya Revolutsiya, formerly Gangut, in 1934 following her modernization.
Starting in 1931, the battleship was extensively modified based on experiences with her sisters that had already been modernized. Oktyabrskaya Revolutsiya saw her superstructure enlarged and strengthened to carry larger, more capable gunfire directors and rangefinders. New rangefinders were also fitted to her main gun turrets. Her gunnery was further enhanced with the fitting of new gunnery computers.
Her powerplant was also modernized. Her original powerplant of twenty-five coal-fired boilers (fitted with oil sprayers) was replaced with six oil-fired boilers. The new boilers took up less space, allowing additional bulkheads to be fitted to improve underwater protection. The forward stack was also modified to help direct exhaust gasses away from the tower.
Lastly, the hull itself was modified. The forward bow was enlarged, featuring additional length and flare to improve performance in rough seas. The new bow increased the battleship's length from 181m (594') to a new maximum of 185m (607').
While perhaps the most outdated battleships that were still in service at the start of the Second World War, the modifications still make the Gangut class battleships much more effective. In the roles that they were employed during the way, namely fire support and as floating anti-aircraft batteries, they remained valuable weapons in the Soviet arsenal.