The 1950s saw considerable growth for the Soviet Navy in regards to its submarine fleet which eventually rivaled that of the United States. The Romeo-class (Project 633) was a new diesel-electric powered group that proved one of the most numerous of its type during the Cold War period (1947-1991), numbering 133 total boats before the end. The series went on to see service with the Soviet Navy as well as the navies of China, North Korea, Algeria, Bangladesh, Bulgaria, Egypt, and Syria but its arrival was dampened somewhat by the rise of nuclear-powered submarines begin to take hold in the Soviet naval inventory.
The Romeo-class succeeded the Whiskey-class boats in Soviet service but were, themselves, succeeded by the much improved Foxtrot-class.
The modern North Korean Navy makes some use out of its obsolete Romeo-class fleet (as of 2017). These were received from China in pre-assembled kits which were then completed at North Korean shipyards. At least twenty or so are thought to be in inventory though their value tactical remains suspect. The fleet is thought to be facing (or has already faced) decommissioning in favor of the arriving Sang-O class (detailed elsewhere on this site). The Romeo-class boats from China were known as "Type 033" and this design emerged as a local development/evolution of the Romeo-class boat forced on the nation due to the Sino-Soviet Split. Improvements and redesigns were made to the class throughout its service life by China.
As designed, the Romeo-class boats had a surfaced displacement of 1,475 tons and a submerged displacement of 1,830 tons. Overall length reached 251.2 feet with a beam measuring 22 feet and a draught of 17 feet. Power was from 2 x Marine diesels outputting 4,000 horsepower for surface running and a pair of electric motors for undersea running. These all drove power to 2 x shafts astern. Surfaced speeds could reach over 15 knots and submerged speeds topped at 13 knots. Range was out to 9,000 miles.
Aboard was a crew of fifty-four which included ten officer-level personnel. A complete radar, sonar and Electronic Warfare (EW)/countermeasures fit was also installed. Armament was 8 x 533mm (21") torpedo tubes arranged as six bow-facing and two stern-facing mountings.
Their profile was consistent with submarines of the period. The bow was sharp and the deck ran relatively level from bow to stern. The sail was a low-profile, contained design which was seated just ahead of midships. The bow has a bulge along its lower section housing the bow-mounted sonar system. The stern held the rudder control scheme as well as the twin propeller units.
The Soviet Navy originally called for fifty-six of the boats but only twenty were completed from the period spanning 1957 into 1961 - namely because of the growing presence of nuclear-powered types. The rest of the lot were sold to foreign powers (Soviet allies) around the world where most have been decommissioned and scrap. A scant few are thought to remain in Russian Navy service as submarine classrooms and little else. By and large, the design is obsolete by modern standards and holds little tactical value in naval warfare today.