Russian pumpjet-equipped submarine to return to sea

Russia’s only conventional submarine fitted with a pumpjet propulsion system is to be returned to sea later this year, according to the shipyard in Crimea where the boat is undergoing modernisation and repairs.

In comments reported by Russian state news agency TASS on 25 January, a spokesman for No 13 Maintenance Shipyard in Sevastopol said work on the Project 877V Kilo-class diesel-electric submarine Alrosa would be completed in 2021.

“Technical readiness of Alrosa is 80%,” he said.

Commercial satellite imagery shows that Alrosa, with its distinctive pumpjet propulsion system, has been at the shipyard either tied up pierside or in one of its floating dry docks, continuously since early 2015. Overhead satellite imagery and still imagery taken from the shore shows that the submarine’s upper deck plating was removed for most of this period, exposing its pressure hull to allow access for workers.

By July 2019 the submarine had been taken out of the water into one of the shipyard’s floating dry docks. Still and satellite imagery from this period shows the submarine hull and sail covered in scaffolding, indicating intensive work was under way.

Alrosa is the only Project 877V ever built, with its pumpjet propulsion replacing the traditional propellers used on legacy Project 877 and newer Project 363.3 submarines. The pumpjet is believed to reduce acoustic signatures because it relies on fewer mechanical components and reduces cavitation effects linked to propellers.

The latest Borey-class nuclear-powered ballistic missile submarines have adopted a newer version of the pumpjet propulsion system.