The Foxtrot class was the NATO reporting name of a class of diesel-electric patrol submarines that were built in the Soviet Union. The Soviet designation of this class was Project 641.
The Foxtrot class was designed to replace the earlier Zulu class, which suffered from structural weaknesses and harmonic vibration problems that limited its operational depth and submerged speed. The first Foxtrot keel was laid down in 1957 and commissioned in 1958 and the last was completed in 1983. A total of 58 were built for the Soviet Navy at the Sudomekh division of the Admiralty Shipyard (now Admiralty Wharves), St. Petersburg. Additional hulls were built for other countries.
The Foxtrot class was comparable in performance and armament to most contemporary designs. However, its three screws made it noisier than most Western designs. Moreover, the Foxtrot class was one of the last designs introduced before the adoption of the teardrop hull, which offered much better underwater performance. Also, although the Foxtrot was larger than a Zulu Class Submarine, the Foxtrot Class had 2 of it's 3 decks dedicated to batteries that gave it a range of 10 days but adding weight making the Foxtrot's average speed a slow 2 knots. Due to the batteries taking up 2 decks, it meant that conditions were relatively small with space comparing to older submarines such as the much older American Balao Class Submarine. The Foxtrot class was completely obsolete by the time the last submarine was launched. The Russian Navy retired its last Foxtrots between 1995 and 2000, units were scrapped and disposed of for museum purposes. The last operational unit, Zaporizhzhia, served in the Ukrainian Naval Forces until it was surrendered to Russia on March 22, 2014, as part of the Russian annexation of Crimea. Russia decided not to accept it due to its age and operational unsuitability.