The Pluviôse class were built as part of the French Navy's 1905 building program to a double-hull design by Maxime Laubeuf.

[4] The first six boats completed were armed with a single 450-millimeter (17.7 in) internal bow torpedo tube, but this was deleted from the rest of the submarines after an accident with their sister Fresnel in 1909.

The other launchers were a rotating pair of Drzewiecki drop collars in a single mount positioned on top of the hull at the stern.

[5] Thermidor, named after the second month of summer in the French Republican Calendar, was ordered on 26 August 1905 from the Arsenal de Cherbourg.

Both submarines suffered damage, particularly Watt, which sustained a gash over 40 centimetres (16 in) in length in her external port ballast tank that required a substantial period of time to repair.