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 the 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.

The long and wide floating dock was owned by Shipyard No. 82 and stationed at Roslyakovo, near Murmansk. In November 2018, the dock sank after a power outage while holding the aircraft carrier/ aircraft cruiser .

History

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. 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 products had dwindled following the 1973 oil crisis, and bidding for the dry dock was one of the shipyard's attempts to diversify its portfolio. With an agreed-upon delivery time of 18 months from the date of contract signing, the work was split between two shipyards in order to speed up construction: Götaverken Arendal built five of the seven sections while the nearby Eriksbergs Mekaniska Verkstad supplied the remaining two; the sections were joined together afloat using underwater welding. The floating dock was named ''PD-50'' (russian: ПД-50, links=no); "PD" being short for "Plavuchiy Dok" (russian: Плавучий док, lit=floating dock, links=no).

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.

On 22 September 1979, ''PD-50'' began its delivery voyage to Murmansk under tow by two Dutch tugboats, and . 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. 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.

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

On 29 December 2011, the Russian Delta IV-class nuclear submarine caught fire while being docked in ''PD-50''. The fire was extinguished by partially submerging ''PD-50'' twice with the K-84 on top.

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

On 30 October 2018, the was damaged when ''PD-50'' suddenly sank under it, causing one of the dock's 70-ton cranes to crash onto the ship's flight deck. One shipyard worker went missing and four others required medical attention, one of whom later died at the hospital.

Replacement

In July 2019, and Saint Petersburg company Investments Engineering Construction (I.I.S.) signed a contract for reconstruction and modernization of Shipyard No. 35 in Murmansk. As part of the RUB20 billion (US$311.5 million) deal, two adjacent dry docks at the plant will be merged into a single dock by demolishing a partition between them. 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 of Russia's largest vessels, such as the battlecruiser . As of December 2019, work on reconstruction of the shipyard was underway.

References

External links

Project 7454 (PD-50)

{{2018 shipwrecks

1979 ships
Auxiliary ships of the Soviet Navy
Drydocks
Maritime incidents in 2018
Maritime incidents in Russia
Murmansk
Ships built in Gothenburg
Ships of the Russian Northern Fleet
Soviet Union–Sweden relations