The Soviet Navy's Project 611 (NATO reporting name: Zulu class) were one of the first Soviet post-war attack submarines. They were roughly as capable as the American GUPPY fleet-boat conversions. They were a contemporary of the Whiskey class submarines and shared a similar sonar arrangement. Their design was influenced by the German Type XXI U-boat of the World War II era. The Zulus were the basis for the very successful Foxtrot class submarine, which lent their hull to the Golf class of ballistic missile submarine.