# Pluviôse-class submarine

The Pluviôse-class submarines were a group of 18 submarines built for the French Navy in the first decade of the 20th century. Before World War I, two were accidentally lost, but one of these was salvaged and put back into service. Four others were lost during the war and the survivors were stricken in 1919.

## Design and description

The Pluviôse class were built as part of the French Navy's 1905 building program to a double-hull design by Maxime Laubeuf. The submarines displaced 404 metric tons (398 long tons) surfaced and 553 metric tons (544 long tons) submerged. They had an overall length of 51.12 meters (167 ft 9 in), a beam of 4.96 meters (16 ft 3 in), and a draft of 3.15 meters (10 ft 4 in). Thermidor differed from her sisters as she was built to test the hull shape planned for the following Brumaire class. She had an overall length of 52.15 m (171 ft 1 in), a beam of 5.42 m (17 ft 9 in) and displaced 396 t (390 long tons) on the surface and 551 t (542 long tons) underwater. The submarines had a crew of 2 officers and 23 enlisted men.
For surface running, the boats were powered by two 350-metric-horsepower (345 bhp; 257 kW) triple-expansion steam engines, each driving one propeller shaft using steam provided by two Du Temple boilers. When submerged each propeller was driven by a 230-metric-horsepower (227 bhp; 169 kW) electric motor. On the surface they were designed to reach a maximum speed of 12 knots (22 km/h; 14 mph) and 8 knots (15 km/h; 9.2 mph) underwater. The submarines had a surface endurance of 865 nautical miles (1,602 km; 995 mi) at 11.6 knots (21.5 km/h; 13.3 mph) and a submerged endurance of 70 nmi (130 km; 81 mi) at 2.8 knots (5.2 km/h; 3.2 mph).
The first six boats completed (Pluviôse, Messidor, Ventôse, Germinal, Floréal and Prairial) were armed with a single 450-millimeter (17.7 in) internal bow torpedo tube, but after an accident that lead to the sinking of Fresnel in 1909, the tubes were removed from Pluviôse and Messidor. A ministerial order of 18 March 1910 added one to Vendémiaire while she was still under construction, but the bow tubes were deleted from the rest of the class. All of the boats were fitted with six 450 mm external torpedo launchers; the pair firing forward were fixed outwards at an angle of seven degrees and the rear pair had an angle of five degrees. Following a ministerial order on 22 February 1910, the aft tubes were reversed so they too fired forward, but at an angle of eight degrees. The other launchers were a rotating pair of Drzewiecki drop collars in a single mount positioned on top of the hull at the stern. They could traverse 150 degrees to each side of the boat. The Pluviôse-class submarines carried eight torpedoes; those with bow tubes carried their reload in the torpedo compartment.

## Ships in class

Pluviôse-class submarines :
| Name | Builder | Laid down | Launched | Commissioned | Fate |
| Ampère Q68 | Arsenal de Toulon | 1906 | 30 October 1909 | 1 November 1910 | Stricken, 12 November 1919 |
| Berthelot Q66 | Arsenal de Rochefort | 1906 | 19 May 1909 | 1 February 1910 | Stricken, 1 December 1919 |
| Cugnot Q76 | Arsenal de Rochefort | 1906 | 14 October 1909 | 10 September 1910 | Stricken, 1 December 1919 |
| Floréal Q54 | Arsenal de Cherbourg | 1906 | 18 October 1908 | 16 June 1909 | Sunk in collision with British armed boarding steamer HMS Hazel, 2 August 1918 |
| Fresnel Q65 | Arsenal de Rochefort | 1906 | 16 June 1908 | 22 February 1911 | Torpedoed by Austro-Hungarian destroyers, 5 February 1915 |
| Fructidor Q58 | Arsenal de Cherbourg | 1906 | 13 November 1909 | 29 June 1910 | Stricken, 12 November 1919 |
| Gay-Lussac Q69 | Arsenal de Toulon | 1906 | 17 March 1910 | 14 January 1911 | Stricken, 1 December 1919 |
| Germinal Q53 | Arsenal de Cherbourg | 1906 | 7 December 1907 | 30 December 1908 | Stricken, 1 December 1919 |
| Giffard Q77 | Arsenal de Rochefort | 1906 | 10 February 1910 | 13 October 1910 | Stricken, 1 December 1919 |
| Messidor Q56 | Arsenal de Cherbourg | 1906 | 24 December 1908 | 30 November 1909 | Stricken, 12 November 1919 |
| Monge Q67 | Arsenal de Toulon | 1906 | 31 December 1908 | 2 August 1910 | Rammed by Austro-Hungarian scout cruiser SMS Helgoland, 29 December 1915 |
| Papin Q64 | Arsenal de Rochefort | 1906 | 4 January 1908 | 1 September 1909 | Unknown |
| Pluviôse Q51 | Arsenal de Cherbourg | 1906 | 27 May 1907 | 5 October 1908 | Sunk in collision, 26 May 1910. Raised and repaired. Stricken, 12 November 1919 |
| Prairial Q55 | Arsenal de Cherbourg | 1906 | 26 September 1908 | 16 June 1909 | Sunk in collision with SS Tropic, 29 April 1918 |
| Thermidor Q57 | Arsenal de Cherbourg | 1906 | 3 July 1909 | 13 July 1910 | Stricken, 12 November 1919 |
| Vendémiaire Q59 | Arsenal de Cherbourg | 1906 | 7 July 1910 | 4 February 1911 | Sunk in collision with French battleship Saint Louis, 8 June 1912 |
| Ventôse Q52 | Arsenal de Cherbourg | 1906 | 15 September 1907 | 5 October 1908 | Stricken, 1 December 1919 |
| Watt Q75 | Arsenal de Rochefort | 1906 | 18 June 1909 | 15 March 1910 | Stricken, 1 December 1919 |

## Service

The Pluviôse class were acknowledged to be good sea boats and saw action throughout the First World War on patrol and close blockade duty. Of the eighteen built, five were lost. One (Vendémiaire) was accidentally lost prior to the war, in 1912. Two others, Floréal and Priarial, were lost accidentally during the conflict, while Monge and Fresnel were lost in action.