PD-50

PD-50 (Russian: ПД-50), Soviet designation Project 7454, was a Russian large floating dry dock built at the Götaverken Arendal shipyard in Gothenburg, Sweden and commissioned in 1980s. At the time, it was the world's largest floating dry dock and used primarily to service the ships and submarines of the Northern Fleet.

PD-50 (left) in Roslyakovo, August 2016
History
Soviet Union, Russia
Name: PD-50 (ПД-50)
Owner: Shipyard No. 82 (Rosneft; 2013–)
Ordered: March 1978
Builder: Götaverken Arendal, Gothenburg, Sweden
Yard number: 910
Completed:
  • August 1979 (planned)
  • August 1980 (final)
In service: 1980–2018
Homeport: Murmansk, Russia
Fate: Sank on 30 October 2018
General characteristics
Type: Floating dry dock
Tonnage: 181,230 DWT
Displacement:
  • 135,460 tonnes (standard)
  • 215,860 tonnes (full load)
Length: 330 m (1,080 ft)
Beam: 88 m (289 ft)
Draught: 6.116 m (20.07 ft)
Propulsion: None
Capacity: 80,000 tonnes
Crew: 175

The 330 metres (1,080 ft) long and 79 metres (259 ft) wide floating dock was owned by Shipyard No. 82 and stationed at Roslyakovo near Murmansk.[1] In November 2018, the dock sank after a power outage while holding the Admiral Kuznetsov.[2]

History
Admiral Kuznetsov dry-docked in PD-50, June 2015

In March 1978, Götaverken Arendal shipyard in Gothenburg, Sweden was awarded a contract for the construction of the world's largest floating dry dock for the Soviet Union.[3] While the company had previously built mainly oil tankers and bulk carriers, it was struggling for new orders after demand for one of its main product had dwindled following the 1973 oil crisis, and bidding for the dry dock was one of the attempts to diversify the shipyard's portfolio.[4] With delivery time agreed as 18 months from signing the contract,[3] the work was split between two shipyards in order to speed up the construction: Götaverken Arendal would build five of the seven sections while the nearby Eriksbergs Mekaniska Verkstad would supply the remaining two parts, and the sections would be joined together afloat using underwater welding.[5] The floating dock was named PD-50 (Russian: ПД-50); "PD" being short for "Plavuchiy Dok" (Russian: Плавучий док; literally "floating dock").

In August 1979, the nearly-finished PD-50 was towed to open sea for trials. During the final test, which involved finding out how fast the submerged dock could be deballasted, two ballast water tanks partially collapsed due to underpressure. The floating dry dock was hastily towed back to Arendal with visible denting on the shell plating and the shipyard workers scrambled to fix the damage. The repairs were completed in early September and PD-50 was handed over to the customer.[3][4][5]

On 22 September 1979, PD-50 began its delivery voyage to Murmansk under tow by two Dutch tugboats, Smit Rotterdam and Smit London. On 3 October, after sailing around the Norwegian coast, the floating dry dock broke free in a storm and was blown ashore on the Soviet side of the Norwegian border.[3][5] The grounding of the brightly-illuminated PD-50 was witnessed by Soviet border guards who later described the incident as if a small city had appeared from the sea, only to be driven on the rocks by the storm.[4]

While the damage to the grounded dry dock was extensive, PD-50 was deemed repairable. After refloating, it was towed first to Kirkenes and later to a shipyard in Stord. The repairs included lifting PD-50 fully out from water using pontoons[4] and replacing 4,000 tonnes of steel.[5] In September 1980, one year after the grounding, PD-50 finally reached Murmansk.[3]

On 29 December 2011, Russian Delta IV-class nuclear submarine Ekaterinburg (K-84) caught fire while being docked in PD-50. The fire was extinguished by partially submerging PD-50 twice while K-84 was atop it.[6]

In 2013, the Russian oil company Rosneft took over Shipyard No. 82 and its assets, including PD-50, in preparation of turning the old naval shipyard into a base for the company's Arctic operations. This has caused an outrage in the naval circles as the shipyard was one of the few in Russia with facilities capable of docking the country's largest surface vessels.[7][8]

On 30 October 2018, Russian aircraft carrier Admiral Kuznetsov was damaged when PD-50 suddenly sank under it,[9][10] and one of the dock's 70-ton cranes crashed onto the ship's flight deck.[11] One shipyard worker went missing and four others required medical attention, one of whom later died in hospital.[10][12]

Replacement

In July 2019, Zvezdochka Ship Repair Center JSC and St. Petersburg company Investments Engineering Construction (I.I.S.) signed a contract for reconstruction and modernization of the Shipyard No. 35 located in Murmansk. As part of the RUB20 billion (US$311.5 million) deal, two adjacent dry docks at the plant will be merged into one joint dock by a demolition of a partition between them and walls, slipways and other dock equipment will be modernized. After the modernization, it will be the largest dry dock in Russia, capable of docking Russia's sole aircraft carrier Admiral Kuznetsov as well as other country's largest vessels, such as the battlecruiser Pyotr Velikiy.[13][14] As of December 2019, the work on reconstruction of the shipyard was underway.[15]

References
  1. ""Звездочка" продолжит ремонт "Адмирала Кузнецова" в соответствии с графиком" [Zvezdochka Ship Repair Center will continue to repair "Admiral Kuznetsov" as scheduled] (in Russian). Interfax. 30 October 2018. Retrieved 5 November 2018. ЧП с плавучим доком ПД-50 (принадлежит 82-му судоремонтному заводу)
  2. Gallagher, Sean (30 October 2018). "Russia's only aircraft carrier damaged as its floating dry dock sinks". Ars Technica. Retrieved 5 November 2018. Due to interruptions in the supply of electric power to the PD-50, the floating dock dived out in an off-design mode.
  3. Lamér, Inkeri (2017). Tung Metall – Finska fartygsbyggare i Göteborg (PDF) (in Swedish). Siirtolaisinstituutti. p. 38. ISBN 978-952-7167-43-4. Archived from the original (PDF) on 2019-04-07. Retrieved 2019-04-07.
  4. Shiryaev, Valery (6 December 2018). "Залег на дно". Novaya Gazeta (in Russian). Retrieved 7 April 2019.
  5. Hansen Siilin, Love (18 November 2018). "39 års olycka för Arendals stolthet". Göteborgs-Posten (in Swedish). Retrieved 7 April 2019.
  6. Roblin, Sebastien (3 November 2018). "A Huge Floating Drydock Sank and Nearly took Russia's Only Aircraft Carrier with It". The National Interest. Retrieved 5 November 2018. the submarine Yekaterinburg caught fire on PD-50 in 2011 while loaded with nuclear missiles and had to be flooded twice to put out the blaze.
  7. Staalesen, Atle (7 December 2016). "Murmansk awaits Rosneft's investments". The Independent Barents Observer. Retrieved 7 April 2019.
  8. Staalesen, Atle (7 August 2018). "Navy gives way to oilmen in Murmansk shipyard". The Independent Barents Observer. Retrieved 7 April 2019.
  9. Staalesen, Atle (30 October 2018). "Aircraft carrier is damaged as dry dock sinks". The Barents Observer. Retrieved 2018-11-08.
  10. "Russia's largest floating dock sinks, while nation's sole aircraft carrier still inside". RT International. 30 October 2018. Retrieved 2018-10-30.
  11. Rainsford, Sarah (30 October 2018). "Russian aircraft carrier Admiral Kuznetsov damaged by crane". BBC News. Retrieved 5 November 2018. Rescuers are searching for a missing ship-worker. Four others needed medical attention after falling into the icy sea. Russian officials insist the damage is "not critical" but the 70-tonne crane caused a gash on the Kuznetsov's deck of up to 5m (16ft).
  12. "Worker Dies From Injuries Sustained In Sinking Of Russian Dry Dock". Radio Free Europe/Radio Liberty. 18 November 2018. Retrieved 2019-04-08.
  13. "Murmansk gets Russia's biggest dry dock". thebarentsobserver.com. 28 May 2019. Retrieved 2 December 2019.
  14. "Заключен контракт на реконструкцию сухих доков на 35-м судоремонтном заводе в Мурманске". bmpd.livejournal.com. 15 July 2019. Retrieved 2 December 2019.
  15. "На 35-м судоремонтном заводе ведутся активные работы по реконструкции сухого дока". bmpd.livejournal.com. 2 December 2019. Retrieved 2 December 2019.
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