The Lagrange-class submarines were constructed as part of the French fleet's expansion programmes from 1913 to 1914. The ships were designed by Julien Hutter, who slightly modified his previous project, the s, using two Parsons steam turbines with a power of 20000NaN0.[1] During construction, though, the idea was abandoned and the ships were instead equipped with diesel engines.[1]
75.2m (246.7feet) long, with a beam of 6.3m (20.7feet) and a draught of 3.6m (11.8feet),[2] Lagrange-class submarines could dive up to 500NaN0. The submarines had a surfaced displacement of 9200NaN0 and a submerged displacement of 13180NaN0.[2] Propulsion while surfaced was provided by two2600hp diesel motors built by Swiss manufacturer, Sulzer, and two1640hp electric motors.[1] [3] The submarines' electrical propulsion allowed them to attain speeds of 11kn while submerged and on the surface.[1] They had surfaced range of 4300nmi at 10kn and a submerged range of 125nmi at 5kn.[2] [1]
The ships were equipped with eight450mm torpedo tubes (fourin the bow; twostern and twoexternal), with a total of tentorpedoes and two75mm guns.[3] The crew of a ship comprised forty-sevenmen.[3] [4]
Of the fourLagrange-class submarines, threewere built in the Arsenal de Toulon and one in the Arsenal de Rochefort.[3] [5] The ships were laid down between 1913 and 1914[2] and launched between 1917 and 1924. The ships were named after French scholars: Joseph-Louis Lagrange, Pierre-Simon Laplace,[4] Henri Victor Regnault and the constructor of submarines Gaston Romazzotti.
| Name | Laid down | Launched | Completed | Fate | |
|---|---|---|---|---|---|
| 1913 | 8December 1919 | 1921 | Stricken in 1937 | ||
| 1913 | 31May 1917 | February 1918 | Stricken in 1935 | ||
| 1913 | 25June 1924 | 1924 | Stricken in 1937 | ||
| 1914 | 31March 1918 | September 1918 | Stricken in 1937 |
Of the foursubmarines, only twowere commissioned before the end of World War I: Lagrange and Romazzotti,[4] which operated in the Mediterranean Sea.[1]
From 1922 to 1923, the ships underwent a major refit in which they received new major conning towers, bridges and periscopes.[1] All ships served in the Mediterranean Sea until 1935 for Lagrange and 1937 for the other threeships.[2] [3]