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Alfa class

Nuclear-powered attack submarine

Alfa class submarine

The Alfa class boats are the fastest attack submarines ever built

Country of origin Soviet Union
Entered service 1971
Crew 31 men
Diving depth (operational) 350 m
Diving depth (maximum) 750 m
Sea endurance 50 days (stores)
Dimensions and displacement
Length 81 m
Beam 9.5 m
Draught 8 m
Surfaced displacement 2 800 tons
Submerged displacement 3 680 tons
Propulsion and speed
Surfaced speed 20 knots
Submerged speed 42 knots
Nuclear reactors 1 x 155 MW
Steam turbines 2 x 40 000 hp
Torpedoes 6 x 533 mm torpedo tubes for conventional or nuclear-tipped torpedoes
Other up to 36 mines in place of torpedoes


   The second Soviet titanium-hulled submarine design, the Project 705 Lira, known in the West as the Alfa class, came to light in December 1971, when the first unit was commissioned. Six more followed in 1977-81.

   The Alfa class was the world's fastest and deepest diving submarines as of their time. An extensive automation allowed to reduce crew to only 30 men. These advanced submarines had their crews completed exclusively from officers and warrant-officers. It also featured an advanced low drag configuration and was extremely maneuverable. The Alfa class submarines were significantly smaller than contemporary attack submarines.

   A single reactor and turbine plant driven the boat at the phenomenal 42 knots (78 km/h) under water. Reactor's power could be rapidly increased, as well as the submarine's speed. However what was not realized at the time was that there was a serious flaw in the lead-bismuth system of the Alfa's 40 000 hp reactor cooling system. The plant was very unreliable, and the cost led to the Project 705 Lira boats being nicknamed the 'Golden Fish'.

   Alfas also had sophisticated crew rescue system. It provided safe exit for entire crew from maximum depth.

   When British and American submariners first encountered the Alfa they were astounded. The result that NATO navies allocated massive funding to the development of new deep-running torpedoes.

   During the Cold War Soviet titanium technology was far in advance of the West, requiring fewer passes to achieve a successful weld. Successors of the Alfa class became the Sierra I class (2 boats built) and further improved Sierra II class (2 boats built). These were also extremely expensive titanium-hulled boats. However the cost of the hulls limited the numbers built, despite advantages in depth, underwater speed and resistance to damage.

   The last Alfa class boat was decommissioned in 1996.


Name Laid down Launched Commissioned Status
K-64 1968 1969 1971


K-123 1967 1976 1977 decommissioned
K-316 1969 1974 1978 decommissioned
K-432 1967 1977 1978 decommissioned
K-373 1972 1978 1979 decommissioned
K-493 1972 1980 1981 decommissioned
K-463 1975 1981 1981 decommissioned



Alfa class submarine

Alfa class submarine

Alfa class submarine


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