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Project 945 Sierra class
Attack Submarine (Nuclear Powered)

The Sierra class has a light and strong titanium pressure hull, enabling these boats to dive to depths of up to 550 meters (1800 feet) and enhancing their survivability, as well as having a low magnetic signature. Designed to engage surface task forces and launch cruise missiles at coastal facilities, the Sierra Project 945 class submarines represented the apex of Soviet attack submarine design. Project 945 was initiated in March 1972, under the direction of Chief designer N.E. Kvasha of TsKB-112 Lazurit. The new Sierra-class submarines were intended to be the primary Soviet attack submarine, incorporating a variety of new sensors, silencing equipment, command systems and countermeasures. The Sierra-class uses a single OK-650 pressurised water reactor, of the same model used in Project 971 (Akula) and on the Mike class submarine Komsomolets.

The Project 945 was generally comparable in performance to early Los Angeles class, though with an arguably superior non-acoustic detection system and integrated acoustic countermeasures system. They were apparently based on the design experience gained with the Project 685 Plavnik [Alfa], although a much larger torpedo room with capacity of up to 40 rounds was provided. Noise levels were reduced by Cluster Guard anechoic tiles on the outer hull.

The boat is outfitted with six 533 mm torpedo tubes capable of using a combination of Granat cruise missiles, torpedoes, antisubmarine missiles, and mines. As with the Alfa, the hull is constructed of titanium alloy, providing deep diving capability and the ability to avoid magnetic anomaly detection. The Sierra-I class had six major compartments: (1) the torpedo room, and battery, (2) crew quarters, officers mess and galley, (3) command center, computer complex, and diesel generators, (4) reactor, (5) main switchboard, pumps and geared turbines, (6) electric motors, steering gear and pumps. The double-hull reduces possible damage to the inner hull's compartments, and the outer hull is coated with anti-hydroacoustic materials making the Sierra more difficult to detect. A crew escape chamber is capable of bringing up the entire crew from a depth of 1,500 meters.

The Sierra-II was an improved and slightly version of the 'Sierra-I' class. The 945.A project (Sierra II) differs from the Sierra I in that the sonar capability of the Sierra II is better and has a reduced acoustic signature. It is five meters longer overall, with a larger blunt sail that is six meters longer than the Sierra I sail. The enlarged sail accommodates two rescue chambers, versus the single chamber on the Sierra-I. The increased hull size provided improved living quarters and quieting measures. It was also equipped with a new American-style spherical bow sonar. This filled the bow section, and the torpedo tubes were moved farther aft and angled out from the centerline. The torpedo room was modified to accomodate the S-10 Granat strategic cruise missile. In contrast to the six compartments on the Sierra-I, the Sierra-II had seven compartments: (1) the torpedo room, and battery, (2) crew quarters, officers mess and galley, (3) sonar room and command center, (4) computer complex, and diesel generators, (5) reactor, (6) main switchboard, pumps and geared turbines, (7) electric motors, steering gear and pumps.

The hulls were built at the factory Krasnoye Soromovo in Nizhny Novgorod and towed in dock via inland waterways to Severodvinsk where construction and testing were completed. By 1976 it had become evident that existing industrial infrastructure was inadequate to mass produce the expensive titanium hulls of this class, and that consequently production rates would not meet force level requirements. Consequently, the Akula attack submarine project using a steel hull was initiated. Construction of the Sierra class was halted in favor of the [probably] less expensive 'Akula' class.

Some analysts suggested that as many as 26 units of the Sierra II class may have been planned. It is generally accepted that one Project 945A Sierra-II unit was laid down [possibly with the name "Mars"] but cancelled prior to completion. This unit may have been the first of a further modified design, designated Project 945B Mars. According to some sources, three units of the Project 945B series were scrapped on the stocks.

A total of four Project 945 and 945A submarines were built in Russia. Authoritative sources provide substantially conflicting information concerning the chronology of this class. More significantly, while some sources [ warships1.com , World Navies Today and USNI Military Database ] suggest that only two units of the Sierra-I class were built, other sources [Bellona and Russia's (USSR) Arms Catalog ] suggest that in fact four units were constructed, a claim which is bolstered by the apparently precise construction chronology for the units. One source of potential confusion is that no sources report pennant numbers for the Barracuda or Kondor, which would appear to reflect a confusion between the class name and the name of individual units. The chronology in Russia's (USSR) Arms Catalog evidently is partially derived from that of Bellona, which is suspect because of the discrepancy between the apparent "as of" date of the document and the reported dates of the chronology. Closer inspection reveals greater consistency in reported milestone dates than in the units or events to which these dates are attributed.

The Project 945 boats were deployed with the Red Banner Northern Fleet, and based in Ara Bay at the Vidyayevo Naval Base. On 11 February 1992, the K-239 Tula [ex-Karp] collided with the American submarine Baton Rouge just off Kildin Island near the Kola Coast. After the collision, the submarine returned to base, but it was later transferred to Zvezdochka Shipyard in Severodvinsk for upgrades, maintenance and repair. As of April 1995, K-239 was still at the shipyard in Severodvinsk.

K-276 Krab was decommissioned in 1997, after only seven years in service, due to a lack of funding for a needed overhaul. Most sources report that both Project 945A class submarines were decommissioned in 1997 as a result of high operating costs, though some sources suggest they may remain in service.

As of January 2003, Janes thought that only one Sierra was thought to be operational, while USNI Military Database thought there were 3 in service [2 SIERRA-II-class and 1 SIERRA-I-class]. As of 2007 the International Institute of Strategic Studies reported that there were two SIERRA-II-class boats in service, with one SIERRA-I-class unit reported "in reserve". The "in reserve" construct can be difficult to understand at times. The Soviets seemed never to throw anything away, but at least followed much the same practice as the US Navy, namely that older warships that were inactive and unlikely to return to service were stored in separate anchorages from ships which remained part of the active fleet, even if currently undergoing maintenance. The post-Soviet Russian Navy has not been quite so fastidious, possibly not itself knowing or being able to acknowledge the mid-term fate of many ships. The result was submarine bases at which evidently active boats were moored along side submarines that had not gotten under way for some years. Even during the Soviet era, the Red Fleet spent far more time in port than at sea, and more recent Russian practice may represent a sensible extension of an operational lethargy focused more on preserving difficult to maintain hardware than on honing crew skills. During the 1990s the status "in reserve" was frequently taken as the equivalent of "stricken" but as some long-dormant vessels returned to life in the new century, "in reserve" may simply mean awaiting reactivation.

The Russian Navy will refit, modernize and recommission two Sierra class (Project 945) titanium-hull nuclear-powered attack submarines by 2017, the Zvezdochka shipyard said on 05 March 2013. The shipyard signed a modernization contract for the Karp and the Kostroma with the Defense Ministry in December 2012. The K-239 Karp (Carp) was the first Project 945 (Barrakuda) submarine, which entered service with the Soviet Navy in 1984. Karp has been sitting at the shipyard since 1994, and the submarines titanium hull is in a very good condition but a significant part of its equipment is missing. The submarines sonar and navigation systems will be replaced and their reactors refuelled. The K-276 Kostroma was commissioned in 1986 and had to be repaired after a February 11, 1992 collision with the American submarine USS Baton Rouge (SSN-689) while on patrol off Kildin Island near Severomorsk. The US Navy said the collision occurred more than 12 miles (22 km) from shore, in international waters. In addition to the Karp and the Kostroma, the Pskov and the Nizhny Novgorod were built in the early 1990's and were in service with the Northern Fleet.

The Russian Defense Ministry has signed a contract to refit two Soviet-era Sierra-class multipurpose nuclear submarines, the Zvezdochka shipyard said 14 May 2014. "A contract was signed with the Defense Ministry to extensively refit two Project 945 [NATO reporting name Sierra]. One of the submarines has remained at the shipyard for over 10 years, the other will arrive this year," spokesman Yevgeny Gladyshev said. The refit will extend the submarines' service for about 10 years. The shipyard's workers were removing nuclear fuel from the reactor of the first submarine, the Karp, laid down in 1987. The submarine's refit was expected to be completed in 2017.

On December 28, 2015, Pskov sailed from Nerpa to her home base Vidyayevo on the Kola Peninsula, some 80 kilometres east of Russias border to Norway. The hull of Pskov is one of the most expensive ever built among the worlds fleet of underwater warfare vessels. Titanuim was used by the Soviet Union enabling the submarine to dive to greater depths since the hull is stronger and lighter and therefor resists pressure better than steel. Unlike steel titanium does not corrode. Construction of Pskov those days known under the name B-336 started in 1989 and the submarine was commissioned in 1993 as the last one built in titanium. The modernisation allowed to significantly extend the operating life of the submarine and continue its further operation in the Arctic.

By 2018 there were two nuclear submarines of Project 945 Barracuda at the disposal of the Navy. They were planned to be updated and improved. Since 2013 the ship K-239 "Karp" was under repair. Due to the age of the technology, it took a lot of time and energy to restore it. In addition, the project provides for the replacement of a part of the on-board equipment and ensuring compatibility with the Kalibr-PL missile system. As a result, the work on the "Karp" will have to be completed only by the end of the decade. Soon after this, the second submarine of project 945 - K-276 Kostroma will arrive at the Zvezdochka plant. Its modernization will continue, at least until the mid-twenties.

Director of the "Zvezdochka" ship repair center Sergey Marichev shared his opinion on the possible repair of the 945 submarines. Repair of two titanium submarines of the project 945 "Karp" and "Kostroma" was suspended indefinitely, director of the center of ship repair "Star" Sergei Marichev said in an interview with TASS 25 July 2018.

"The contract for the repair of these ships was concluded in 2012 and, according to the customer's order, was suspended in 2015. Decisions on the inventory of the orders have not yet been made. From the point of view of technology, in my opinion, the decision was made right: the expediency of repairing and modernizing titanium ships questionable, " said Marichev. The head of the enterprise noted that these are complex submarines, and therefore problems with the equipment are inevitable. At the same time, working with titanium bodies requires special conditions. "Objectively speaking, repairing them will be more expensive and more difficult, exploit and maintain technical readiness - too, and according to characteristics the ship will not exceed other projects of multi-purpose nuclear submarines," Marichev said.

"At the same time, the range of tasks that these ships will be able to solve after modernization is not wider than those that the same "Barca" and "Yaseni" will solve. Objectively speaking, repairing them will be more expensive and more difficult, exploit and maintain technical readiness - too, and the characteristics of the ship will not exceed other projects of multi-purpose nuclear submarines."



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