Foxtrot-class submarine

Foxtrot class

A Cuban Foxtrot underway
Class overview
Builders	Sudomekh, Leningrad
Operators	Soviet Navy /  Russian Navy  Libyan Navy  Cuban Revolutionary Navy  Indian Navy  Polish Navy  Ukrainian Navy
Preceded by	Zulu-class submarine Romeo-class submarine
Succeeded by	Tango-class submarine
Subclasses	Kalvari class Vela class
Built	1957–1983
In service	1958–2014
In commission	1958–2014
Completed	75
Lost	1
Preserved	7
General characteristics
Type	Submarine
Displacement	1,952 long tons (1,983 t) surfaced 2,475 long tons (2,515 t) submerged
Length	89.9 m (294 ft 11 in)
Beam	7.4 m (24 ft 3 in)
Draft	5.9 m (19 ft 4 in)
Propulsion	3 × Kolomna 2D42M 2,000 hp (1,500 kW) diesel engines 3 × Electric motors, two 1,350 hp (1,010 kW) and one 2,700 hp (2,000 kW) 1 × 180 hp (130 kW) auxiliary motor 3 shafts, each with 6-bladed propellers
Speed	16 knots (30 km/h) surfaced 15 knots (28 km/h) submerged 9 knots (17 km/h) snorkeling
Range	20,000 nmi (37,000 km) at 8 kn (15 km/h) surfaced 11,000 nmi (20,000 km) snorkeling 380 nmi (700 km) at 2 kn (3.7 km/h) submerged
Endurance	3-5 days submerged
Test depth	246–296 m (807–971 ft)
Complement	12 officers, 10 warrants, 56 seamen
Armament	10 × torpedo tubes (6 bow, 4 stern) 22 torpedoes

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), Saint Petersburg.^[1] 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 its 3 decks dedicated to batteries. This gave it an underwater endurance of 10 days, but the weight of the batteries made the Foxtrot's average speed a slow 2 knots (3.7 km/h) at its maximum submerged time capability. Due to the batteries taking up 2 decks, onboard conditions were crowded, with space being relatively small even when compared 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;^[2] units were scrapped and disposed of for museum purposes.^[3] During the division of the Soviet Black Sea Fleet, in 1997 one Foxtrot class submarine (later renamed as Zaporizhzhia) was passed to Ukraine as it was not operational since 1991. The ship never effectively served in the Ukrainian Navy and was under repair. In 2005 Ukrainian Ministry of Defence wanted to sell it, but was unsuccessful. Following successful post-repair trials in June 2013, it was recognised as operational.^[4] However, on 22 March 2014 it was surrendered to or captured by Russia as part of the Russian annexation of Crimea.^[5] Russia decided not to accept it due to its age and operational unsuitability. Its subsequent status is unknown.