The Mirka class was the NATO reporting name for a class of light frigates built for the Soviet Navy in the mid to late 1960s. The Soviet designation was Storozhevoi Korabl (escort ship) Project 35 (Mirka I) and Project 35M (Mirka II).

Small fast combatant armed with 76-mm gung, torpedo tubes, and antisubmarine rocket laumchers. The machinery consisted of two shafts with diesels and gas turbines (CODAG). The propellers were in tunnels (similar to water jets). The main caliber of the ship is a paired 76-mm AK-726 in two towers on the bow and stern. The total ammunition load of 76 mm shells on board is 1360 rounds.

The ship of Project 35 had good seaworthiness: it could use weapons with sea waves up to 4 points, to reduce pitching, special pitching dampers were placed on it, and during the design a large cruising range was maintained at an economic speed (2000 nautical miles).

A total of 18 ships were built by Yantar shipyard, Kaliningrad, for the Soviet Navy. In 1970, Zelenodolsk Design Bureau proposed an improved Project 35M. According to this project, one torpedo tube was removed in front of the main mast, two more RBU-6000 were installed on the aft superstructure and the sonars were replaced with newer ones. In total, 8 ships were upgraded under Project 35M. All ships were decommissioned between 1989 and 1992.

Frigate PLK-51 laid down 17 May 1962 at the Yantar Shipyard, Kaliningrad (yard No.176), launched 10 April 1963, commissioned 29 December 1965 and was assigned to the Baltic Fleet.

From 19.05.1966 renamed to SKR-84.

31 August 1966 transferred from the Baltic Fleet to the Black Sea Fleet.

From 02 February 1978 to 12 April 1979 the ship was modernized at the Sevmorzavod named after S.Ordzhonikidze, Sevastopol, by the Project 35M.

Frigate SKR-84 was decommissioned and excluded from the lists of the Black Sea Fleet on 03 July 1992 and scrapped.