French submarine Laplace

The French submarine Laplace (Q111) was a Lagrange-class submarine built for the French Navy built between 1913 and 1919. It was laid down in the Arsenal de Rochefort shipyards and launched on 12 August 1919. Laplace was completed in 1921 and served in the French Marine Nationale until 1935.

Design
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, slightly modifying his previous project Dupuy de Lôme-class submarine, using two Parsons steam turbines with a power of 2000 hp. During construction, the idea of steam propulsion was abandoned and the ships were instead equipped with diesel engines.

Measuring 75.2 m long, with a beam of 6.3 m and a draught of 3.6 m, Lagrange-class submarines could dive up to 50 m. The submarine had a surfaced displacement of 920 t and a submerged displacement of 1318 t. Propulsion while surfaced was provided by two 2600 hp diesel motors built by the Swiss manufacturer Sulzer and two 1640 hp electric motors. The submarines' electrical propulsion allowed it to attain speeds of 11 kn while submerged and 16.5 kn on the surface. Their surfaced range was 7700 nmi at 9 kn, and 4000 nmi at 12 kn, with a submerged range of 70 nmi at 5 kn.

The ships were equipped with eight 450 mm torpedo tubes (four in the bow, two stern and two external), with a total of ten torpedoes, and two on-board guns. The class was also armed with a 75 mm gun with 440 shells. The crew consisted of four officers and forty-three seamen.

Service history
Laplace was built in the Arsenal de Rochefort. It was laid down in 1913 and launched on 12 August 1919, and completed in 1921. It was named in honor of the French astronomer and mathematician Pierre-Simon Laplace. From 1922 to 1923, Laplace underwent a major refit in which it received a new conning tower, bridge and periscope. Laplace served in the Mediterranean Sea until 1935.