French 600 Series submarines

La Doris of the Circé-class submarine of the 600 series
Class overview
Name:	600 Series
Operators:	French Navy
Subclasses:	(600 series): Sirène class Ariane class Circé class (630 series) : Orion class Diane class Argonaute class
Built:	1923–1933
In commission:	1927–1945
Completed:	28
Lost:	18
Retired:	10
General characteristics
Type:	Submarine
Displacement:	609–651 tonnes (599–641 long tons) surfaced 757–822 tonnes (745–809 long tons) submerged
Length:	62.4–65.9 m (205–216 ft)
Beam:	4.9–5.4 m (16–18 ft)
Draught:	6–4.3 m (20–14 ft)
Propulsion:	2 × diesel 1,200–1,420 hp (0.89–1.06 MW) 2 × electric 1,000 hp (0.75 MW)
Speed:	13.5–14 knots (25.0–25.9 km/h; 15.5–16.1 mph) surfaced 7.5–9 knots (13.9–16.7 km/h; 8.6–10.4 mph) submerged
Range:	3,500–4,000 mi (5,600–6,400 km) surfaced 75–82 mi (121–132 km) submerged
Complement:	41
Armament:	7 × 550 mm (22 in) torpedo tubes 1 × 76–100 mm (3.0–3.9 in) deck gun 1–2 × 8 mm (0.31 in) machine guns

The French 600 Series submarines were a series of submarine classes built for the French Navy (Marine Nationale) during the Inter war years.

The 600 Series were seagoing submarines, though designated as coastal-type submarines, built for service in the Mediterranean. They were built to conform to the interwar naval treaties arising from the 1922 Washington and 1930 London conferences, which placed restrictions on the number and size of warships of various types that nations could build. The coastal submarine was limited to a 600-ton surface displacement, though there was no limit placed on the numbers of these vessels that could be built. During this period France was involved in a rivalry with Italy in the Mediterranean, leading to a naval arms race. France took an early lead, but by .. Italian submarine building had overtaken her.

The French 600 series, and the later 630 series, was equivalent to the Italian 600 Series, the British S class, and the German Type VII U-boat.

The 600’s had a surface displacement just above 600 tons; the earliest vessels displaced 609 tons while the last built were 651 tons. They had an endurance of 3,500 to 4,000 miles at 7.5 to 10 knots, with a submerged speed of 7.5 to 9 knots. Their armament was six to seven torpedo tubes (3 forward, 2 midships, and 1 or 2 aft) with an outfit of 9-13 torpedoes. As with all French submarines of this period, the midships torpedo tubes were fitted externally in trainable mounts. They had a single 3 inch/76mm to 3.9 inch/100mm gun, and one to two 8mm machine guns, and were manned by crews of 41 men.

The first 600's were ordered in 1923. The French Navy was content to leave the design features for the boats to the builders, after laying down the specifications. Thus the 12 boats of the series were in three distinct classes, according to the design bureau and shipyard. The subsequent 630 Series were designed and built in the same way, resulting in 16 boats in a further three classes.