Why Russia Is Retiring One Of Its Mighty Delta IV-class Submarines Though the submarine is one of the powerful Delta IV class—once the pride of the Soviet Navy—the boat has had a risky and troublesome history. The Russian Navy is slowly retiring their Delta IV-class submarines, starting with the hull number K-84, the Yekaterinburg. Though for now the rest of the seven-hull class will remain active, the entire class will ultimately be replaced by Russia’s much anticipated Borei-class. The Yekaterinburg currently serves with Russia’s Northern Fleet, and is scheduled to be scrapped in 2022, according to TASS, a Russian state-owned media company.