FS Surcouf (N N 3) Ocean-Going Cruiser Submarine
Although three of the Surcouf-class cruiser submarines were planned, only the Surcouf herself was completed and put to sea, seeing some action in World War 2.
Authored By Staff Writer; Content ©www.MilitaryFactory.com
Surcouf (N N 3) was a mammoth French-built attack submarine developed and built during the interwar years between World War 1 (1914-1918) and World War 2 (1939-1945). At the time of her completion, she represented the largest (by displacement) submarine ever put to sea, a triumph of French naval engineering. She also carried battleship-caliber 8" deck guns, the largest then allowed on submarines by the Washington Naval Treaty (attempting to control naval escalation between world powers), making her one of the more unique vessels entering World War 2.
Surcouf was ordered in December of 1927, launched in October of 1929 and commissioned in May of 1934. She carried the name of one Robert Surcouf (1773-1827) who built his fortune by prowling the Indian Ocean as a privateer and merchant during the latter half of the 18th century and into the 19th century. He was awarded the "Sabre of Honour" and the "Legion of Honour" during his time at sea. The Surcouf submarine served the French Navy under the pennant number of "N N 3" and was intended as a three-strong class though only the single ship was ever completed - serving primarily in the role of experimental cruiser submarine.
Externally, the Surcouf was given a unique design profile as submarines of the period go. She featured the usual tapering at her bow and stern as well as the flat surface deck with her sail positioned at midships in the usual way. However, her sail was extended forwards to encompass a large main gun emplacement which gave the submarine considerable firepower against surface ships. Railing was set from about the forecastle back to the stern. The vessel displaced at 3,300 tons (short) when surfaced and 4,370 tons (short) when submerged. She featured a length of 361 feet, a beam of 29 feet 6 inches and a draught of 23 feet, 9 inches and was typically staffed with 118 personnel including eight officers. The vessel could be stocked with up to 90 days of food.
Power to the submarine was served by 2 x Sulzer diesel engines which were in use when the vessel was surfaced. Underwater propulsion came from 2 x electric motors. This hybrid configuration was typical of submarines of the time and drove twin screws at the stern. Performance-wise, the vessel could reach surfaced speeds of 18.5 knots and submerged speeds of 10 knots. Her range was 10,000 nautical miles when heading at 10 knots on the surface and featured a submerged range of 70 nautical miles when heading at 4.5 knots. The Surcouf being no exception, submarines of World War 2 were required to surface to recharge batteries and oxygen supplies. This represented one of the more vulnerable moments for the boat when under watch from an enemy.
The Surcouf was an attack submarine by design and she was appropriately very well armed for the role. Her armament suite was led by 8 x 550mm (22") torpedo tubes which fed from a stock of 14 torpedoes. This was supplemented by 4 x 400mm (16") torpedo tubes firing from an onboard stock of 8 torpedoes. Her surface armament included 2 x 203mm (8") guns, 2 x 37mm (1.46") anti-aircraft guns and 4 x 13.2mm (0.52") anti-aircraft guns. The 8" guns utilized a rangefinding director from 60-round magazines.