Russian ironclad Petropavlovsk

The Russian ironclad Petropavlovsk (Петропавловск) was ordered as a 58-gun wooden frigate by the Imperial Russian Navy in the early 1860s, but was converted while under construction into an 22-gun armored frigate. She served as the flagship of the Baltic Fleet during the 1860s and 1870s. The ship was decommissioned in 1885, but was not sold for scrap until 1892.

Description
Petropavlovsk was 300 ft long between perpendiculars, with a beam of 50 ft and a draft of 22 ft (forward) and 24 ft (aft). She displaced 6040 LT and was fitted with a blunt iron ram at her bow. Petropavlovsk was considered to be seaworthy; her total crew numbered 680 officers and enlisted men.

The ship was fitted with a horizontal return-connecting-rod steam engine built by the Baird Works of Saint Petersburg. It drove a single four-bladed propeller using steam that was provided by an unknown number of rectangular boilers. During the ship's sea trials, the engine produced a total of 2805 ihp and gave the ship a maximum speed of 11.8 kn. The ship carried a maximum of 375 LT of coal, but her endurance is unknown. She was ship rigged with three masts.

As a heavy frigate, Petropavlovsk was intended to be armed with 54 of the most powerful guns available to the Russians, the 7.72 in 60-pounder smoothbore gun, and four long 36-pounder smoothbores. Her armament was revised when she was converted to an ironclad and she was completed with an armament of twenty 8 in rifled guns and two 60-pounder guns; all of the 8-inch guns were located on the lower deck and the 60-pounders were mounted on the upper deck as chase guns. Later another pair of 60-pounder guns were added on the upper deck. In 1877, the armament on her upper deck was changed and consisted of one 8-inch, one 6 in and ten 3.4 in rifled guns.

The entire ship's side was protected with wrought-iron armor that extended 5 ft below the waterline. It was 4.5 in thick amidships, backed by 10 in of teak, that reduced to 3 in, backed by six inches of teak, in steps beginning 50 ft from the ship's ends.

Construction and service
Petropavlovsk, named for the Siege of Petropavlovsk during the Crimean War, was laid down on 12 January 1861 as a 58-gun heavy frigate at the New Admiralty Shipyard in Saint Petersburg. She was reordered as (converted into) a 22-gun armored frigate on 29 October 1861 while still under construction. The ship was launched on 15 August 1865 and commissioned on 1 August 1867. During the 1860s and 1870s, Petropavlovsk served as the flagship of the Baltic Fleet. She was decommissioned on 15 June 1885, stricken from the Navy List on 4 January 1892 and subsequently sold for scrap.