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| Project 670 Skat (Charlie I) | |
|---|---|
| Name | Project 670 Skat (Charlie I) |
| Nation | Soviet Union |
| Class | Nuclear-powered cruise missile submarine |
| Displacement | 6,200 t surfaced / 7,300 t submerged |
| Length | 107 m |
| Beam | 9.4 m |
| Draft | 6.5 m |
| Propulsion | Two pressurized water reactors, steam turbines, two shafts |
| Speed | 18 kn surfaced / 33 kn submerged |
| Test depth | 300 m |
| Complement | ~100 |
| Armament | 8 SS-N-7 SLCMs, 4 torpedo tubes |
| Built | 1970s |
| Status | Retired |
Project 670 Skat (Charlie I) is a Soviet Cold War nuclear-powered cruise missile submarine class developed to deliver anti-ship strikes with long-range cruise missiles and to perform fleet escort and patrol missions. Conceived during the 1960s under Soviet naval expansion, the class entered service in the early 1970s and represented a focused effort to match Western carrier and surface-combatant threats with submarine-launched cruise missiles. The design balanced speed, endurance, and missile-carrying capacity, reflecting doctrinal priorities articulated by Soviet naval leadership.
Design work originated in Soviet shipbuilding bureaus responding to requirements set by the Ministry of the Navy (Soviet Union), with technical contributions from the Rubin Design Bureau and the Lazurit Central Design Bureau. Influenced by lessons from Project 659 (Hotel), Project 675 (Echo II), and advances in nuclear propulsion pioneered at the Kirov-class battlecruiser program, naval architects prioritized a streamlined hull and hydro-acoustic shaping to improve submerged endurance and reduce detection by NATO ASW forces such as units from the United States Navy and the Royal Navy. The missile compartment was integrated amidships to accommodate the new SS-N-3 Shaddock derivative, while pressure hull arrangements echoed earlier designs like Project 627 (November). Political direction from leaders in Moscow and procurement oversight by the Council of Ministers of the Soviet Union accelerated construction at shipyards in Komsomolsk-on-Amur and Sevmash.
The class used two pressurized water reactors derived from reactor developments in the Soviet nuclear submarine program and shared steam turbine technology standardized across contemporary Soviet designs. The single-hull with a reinforced sail combined features seen in Victor-class submarine and Charlie II-class submarine contemporaries. Noise reduction measures referenced acoustic treatments explored at the Krasnoye Sormovo Factory and the Admiralty Shipyards research teams, while onboard command systems interfaced with tactical datalinks akin to those used on Kresta-class cruiser platforms. Habitability and crew ergonomics followed standards set by the Soviet Navy for nuclear crews, with a complement trained under programs similar to those at the Higher Naval School of Submarine Officers.
Primary offensive armament comprised eight midship-launched submarine-launched cruise missiles based on the SS-N-3 Shaddock family, intended to engage targets at sea and land under guidance regimes developed in conjunction with the Soviet Academy of Sciences aerospace divisions. Torpedo armament and countermeasures included 533 mm torpedo tubes compatible with systems fielded on Victor I-class submarine and acoustic decoys influenced by research at the Central Research Institute of Shipbuilding Technology. Sonar suites integrated bow-mounted and flank arrays developed using acoustic sensor prototypes tested at the Kronshtadt facilities, and fire-control electronics integrated components from institutes associated with the Ministry of Defense (Soviet Union).
Units of the class entered service amid heightened tensions exemplified by events such as the Yom Kippur War and ongoing Cold War confrontations with carrier groups fielded by the United States Sixth Fleet and the United States Seventh Fleet. Deployments concentrated in the Northern Fleet (Soviet Union) and the Pacific Fleet (Russia), conducting patrols, missile exercises, and monitored transits near contested waters patrolled by NATO ASW forces including assets from the North Atlantic Treaty Organization and maritime patrol aircraft like the P-3 Orion. Incidents and close encounters with ships and aircraft from the Royal Australian Navy and the French Navy informed tactical adjustments. Over time, attrition, maintenance burdens at yards such as Sevmash and changing strategic priorities influenced withdrawals from frontline service.
The initial series led to iterative improvements paralleled by a follow-on design developed to carry newer missiles and enhanced sonar arrays; these evolutions coincided with developments seen in the later Charlie II-class submarine and design directions adopted by the Akula-class submarine program. Experimental conversions explored interoperability with command-and-control suites used on surface warships like Kuznetsov-class aircraft carrier escorts, and retrofit proposals examined replacing original missiles with newer cruise missile types studied at institutes affiliated with the Russian Academy of Sciences.
Primary operator was the Soviet Navy, later succeeded in administrative lineage by the Russian Navy for residual hulls. Deployments were concentrated under commands of the Northern Fleet (Soviet Union) and the Pacific Fleet (Russia), with port visits and logistic support handled at bases including Murmansk, Vladivostok, and shipyard facilities in Nerpa and Zvezda. International encounters involved navies such as the United States Navy, Royal Navy, French Navy, and regional forces operating in proximity to patrol areas.
The class demonstrated Soviet emphasis on stand-off anti-ship strike capability and influenced subsequent submarine-launched cruise missile developments pursued by design bureaus like Rubin Design Bureau and Malachite Design Bureau. Operational experience highlighted challenges in missile reliability, acoustic signature management, and maintenance logistics at yards like Sevmash, informing upgrades in the Soviet Navy modernization programs of the 1980s and the Russian Navy reforms of the 1990s. The design's contribution to Cold War maritime deterrence is reflected in doctrinal analyses by scholars associated with institutions such as the Moscow State Institute of International Relations and historical assessments by analysts from the Center for Naval Analyses and equivalent Western think tanks.