Surcouf (N N 3)

Le Surcouf circa 1935 painted in Prussian dark blue
History
France
Name:	Surcouf
Namesake:	Robert Surcouf
Ordered:	4 August 1926
Builder:	Arsenal de Cherbourg
Laid down:	July 1 1927
Launched:	November 18 1929
Commissioned:	April 16 1934
In service:	1934–1942
Refit:	1941
Identification:	Pennant number: N N 3
Honors and awards:	Resistance Medal with rosette
Fate:	disappeared, February 18 1942
General characteristics
Type:	Cruiser submarine
Displacement:	3,250 long tons (3,300 t) (surfaced) 4,304 long tons (4,373 t) (submerged) 2,880 long tons (2,930 t) (dead)
Length:	110 m (361 ft)
Beam:	9 m (29 ft 6 in)
Draft:	7.25 m (23 ft 9 in)
Installed power:	7,600 hp (5,700 kW) (surfaced) 3,400 hp (2,500 kW) (submerged)
Propulsion:	2 × Sulzer diesel engines (surfaced) 2 × electric motors (submerged) 2 × screws
Speed:	18.5 knots (34.3 km/h; 21.3 mph) (surfaced) 10 kn (19 km/h; 12 mph) (submerged)
Range:	Surfaced: 18,500 km (10,000 nmi; 11,500 mi) at 10 kn (19 km/h; 12 mph) 12,600 km (6,800 nmi; 7,800 mi) at 13.5 kn (25.0 km/h; 15.5 mph) Submerged: 130 km (70 nmi; 81 mi) at 4.5 kn (8.3 km/h; 5.2 mph) 110 km (59 nmi; 68 mi) at 5 kn (9.3 km/h; 5.8 mph)
Endurance:	90 days
Test depth:	80 m (260 ft)
Boats & landing craft carried:	2 × motorboats in watertight deck well
Capacity:	280 long tons (280 t)
Complement:	8 officers and 110 men
Armament:	2 × 203 mm (8 in) guns (1 × 2) 2 × 37 mm (1.46 in) anti-aircraft guns (2 × 1) 4 × 13.2 mm (0.52 in) anti-aircraft machine guns (2 × 2) 8 × 550 mm (22 in) torpedo tubes 4 × 400 mm (16 in) torpedo tubes
Aircraft carried:	1 × Besson MB.411 floatplane
Aviation facilities:	Hangar

Seizure of Surcouf
Part of World War II
Date July 3, 1940 Location Plymouth, England, United Kingdom Result British capture of Surcouf
Belligerents
United Kingdom	France
Casualties and losses
3 killed	1 killed

Surcouf (French: ) was the largest French submarine cruiser having served during the Second World War. The boat was sunk by accident or misunderstanding during the night of February 19 1942 in the Caribbean Sea. In tonnage, the boat was also the largest military submarine in the world for the époque. Surcouf – named after the French privateer Robert Surcouf – was the largest submarine ever built until surpassed by the first Japanese I-400-class submarine in 1943.

The Washington Naval Treaty had placed strict limits on naval construction by the major naval powers in regards to displacements and artillery calibers of line ships (French: bâtiments de ligne) and croiseurs. However, no accords was filed in motion for light ships (French: bâtiments légers such (torpilleurs, contre-torpilleurs, frigates or destroyers) neither for submarines. In addition, to ensure the country's protection and that of the empire, France mounted the construction of an important submarine fleet (79 units in 1939). Le Surcouf was supposed to be the first of a series of the submarine cruisers; however, it was the only one produced.

The missions were revolved around the following:

Surcouf had a twin artillery turret with 203 mm (8-inch) guns, the same calibre as that of a heavy cruiser ( the main reason of Le Sourcouf being designated as croiseur sous-marin - "submarine cruiser") provisioned with 600 rounds.

Surcouf was designed as an "underwater heavy cruiser", intended to seek and engage in surface combat. For reconnaissance purposes, the boat carried a Besson MB.411 observation floatplane in a hangar built abaft of the conning tower. However, the floatplane was also mainly used for gun calibration purposes.