Project 122bis (NATO codename Kronshtadt class) submarine chasers were a Soviet design which were exported throughout the communist bloc in the 1950s. The first ship, BO-270, was built at Zelenodolsk in 1945-1947 and a total of 227 were built for Soviet Navy (175) and border guard until 1955. As well as this, twenty Project 357 (Libau class) despatch vessels were built on the same hull, but were lightly armed. Service history The ships served in 1950s–1960s on all Soviet fleets and flotillas in the Baltic Sea, Black Sea, Caspian Sea, Arctic Ocean and Pacific Ocean as part of Soviet coastal anti-submarine defences. Ships were also given to the Soviet Border Guards and were used actively as border patrol ships. Most of the Soviet sub-chasers were decommissioned between 1958 and 1970, although some were in service until the 1990s as training stations. Thirteen of the decommissioned and disarmed ships were delivered to the DOSAAF Voluntary Society for use as training ships. Ships Built in 1946 (launching year): BO-270 (laid up 30.06.1945, launched 27.04.1946, commissioned 27.09.1947 on Caspian Flotilla) BO-171...BO-173 1947: BO-181...BO-187 1948: BO-187...BO-195 1949: BO-196...BO-201 BO-247...BO-255 BO-271...BO-276 1950: BO-277...BO-300 BO-334...BO-338 1951: BO-339...BO-354 BO-356...BO-379 1952: BO-371...BO-402 1953: BO-403...BO-437 1954: BO-438...BO-440 BO-446...BO-453 PSKR-444...PSKR-451, PSKR-436, PSKR-437 BO-454...BO-469 1955: BO-470...BO-480 BO-155 PSKR-424, PSKR-418, PSKR-407 BO-157 PSKR-408, PSKR-419, PSKR-425, PSKR-426 BO-159...BO-163 Export and transferring Albania: MPK-345 (1951), MPK-346 (1951) in 1958 (both returned in 1960), MPK-388 (1952), MPK-389 (1952) in 1958, MPK-394 (1952), MPK-450 (1954) in 1960. Bulgaria: 94 (ex-MPK-160) (1955) and 95 (ex-MPK-162) (1955) in 1957. China: BO-379 (1952), BO-380 (1952), BO-393 (1952), BO-395 (1952), BO-396 (1952), BO-397 (1952) in 1955. In addition, 6 hulls were built at Zelenodolsk in 1954, transferred in parts by railway to Guangzhou (2) and Shanghai (4) and commissioned into the People's Liberation Army Navy, and were designated as the Type 6604 submarine chaser. China had made minor changes during the construction of these boats, the only significant difference between Type 6604 and the original Project 122bis being in the galley, which was modified to better fit Chinese usage. The original electric stove was replaced by an oil stove, so Chinese foods such as stir fry can be cooked more efficiently; the bread storage cabinet was modified to store rice instead. In addition, some empty areas were fenced up to store canned food. Furthermore, 14 built in China with the assistance of Soviet specialists, with 12 completed at the end