''Plongeur'' (French for "Diver") was a French submarine launched on 16 April 1863. She was the first submarine in the world to be propelled by mechanical (rather than human) power. Captain Siméon Bourgeois, who made the plans, and naval constructor Charles Brun began working on the design in 1859 at

Rochefort Rochefort () may refer to: Places France * Rochefort, Charente-Maritime, in the Charente-Maritime department ** Arsenal de Rochefort, a former naval base and dockyard * Rochefort, Savoie in the Savoie department * Rochefort-du-Gard, in the Ga ...

Design

In 1859 the Board of Construction () called naval engineers for designs for a submarine and reviewed three, choosing that submitted by Siméon Bourgeois (later Admiral) and Charles Brun, naming the project ''Plongeur'' with the code name Q00. The submarine used a

compressed-air engine A pneumatic motor (air motor), or compressed air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air energy to mechanical work through either linear or rotary ...

, propelled by stored compressed air powering a

reciprocating engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common fea ...

. The air was contained in 23 tanks holding air at 12.5 bar (1.25

MPa MPA or mPa may refer to: Academia Academic degrees * Master of Performing Arts * Master of Professional Accountancy * Master of Public Administration * Master of Public Affairs Schools * Mesa Preparatory Academy * Morgan Park Academy * Mou ...

, 180

psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ, ψ), the 23rd letter of the Greek alphabet * Psi (Cyrillic) (Ѱ, ѱ), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviatio ...

), taking up a huge amount of space (153 m³/5,403 ft³), and requiring the submarine to be of unprecedented size. The engine had a power of 60 kW (80 hp), and could propel the submarine for 5 nmi (9 km), at a speed of 4 kn (7.2 km/h). Compressed air was also used to empty its ballast tanks, which had a volume of 53 m³ (1,872 ft³).

Ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...

was 212 t (234

ton Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses. Mainly it describes units of weight. Confusion can arise because ''ton'' can mean * the long ton, which is 2,240 pounds ...

s), including a security ballast of 34 t (37 tons). The submarine was armed with a

ram Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...

to break holes in the hull of enemy ships, and an electrically fired

spar torpedo A spar torpedo is a weapon consisting of a bomb placed at the end of a long pole, or spar, and attached to a boat. The weapon is used by running the end of the spar into the enemy ship. Spar torpedoes were often equipped with a barbed spear at ...

, fixed at the end of a pole, though later Admiral Bourgeois (who was, after 1871, chairman of the Commission on Submarine Defenses) opposed the use of torpedoes as the primary weapon in commerce warfare. The submarine was 43 m (140 ft) long and 381 t (420 tons) in

displacement Displacement may refer to: Physical sciences Mathematics and Physics * Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

. A support ship, the ''Cachalot'', followed her in order to resupply the compressed air necessary to her propulsion. A small

lifeboat Lifeboat may refer to: Rescue vessels * Lifeboat (shipboard), a small craft aboard a ship to allow for emergency escape * Lifeboat (rescue), a boat designed for sea rescues * Airborne lifeboat, an air-dropped boat used to save downed airmen ...

(8 × 1.7 m; 26 × 5.6 ft) was provided for the escape of the 12-man complement. Le Plongeur internals

Operational history

The submarine was commanded by Lieutenant de Vaisseau Marie-Joseph-Camille Doré, native of

La Rochelle La Rochelle (, , ; Poitevin-Saintongeais: ''La Rochéle''; oc, La Rochèla ) is a city on the west coast of France and a seaport on the Bay of Biscay, a part of the Atlantic Ocean. It is the capital of the Charente-Maritime department. Wi ...

. On 6 October 1863, ''Plongeur'' made her first trials by sailing down the river Charente, towards the harbour of the Cabane Carrée. On 2 November 1863, ''Plongeur'' was towed towards Port de Barques where her first underwater trials were planned. Because of poor weather conditions, the submarine was eventually towed to

La Pallice La Pallice (also known as ''grand port maritime de La Rochelle'') is the commercial deep-water port of La Rochelle, France. During the Fall of France, on 19 June 1940, approximately 6,000 Polish soldiers in exile under the command of Stanisła ...

and then to the harbour of

(Bassin à flot). On 14 February 1864, during trials in the Bassin à flot, the engine raced due to an excessive admission of compressed air, and the submarine bumped into the quay. Trials were stopped. On 18 February 1864, ''Plongeur'' was towed to La Pallice and dived to 9 m (30 ft).

Stability Stability may refer to: Mathematics *Stability theory, the study of the stability of solutions to differential equations and dynamical systems ** Asymptotic stability ** Linear stability ** Lyapunov stability ** Orbital stability ** Structural sta ...

problems due to its length limited the submarine to dives to a maximum depth of 10 m (33 ft). The front of the submarine would tend to dive first, hitting the bottom, so that the submarine would glide forward. Pumps were installed to compensate for the tilt, but proved too slow to be effective. The installation of longitudinal rudders would have improved stability as later demonstrated by the ''

Gymnote ''Gymnote'' was one of the world's first all-electric submarines and the first functional submarine equipped with torpedoes. Launched on 24 September 1888, she was developed in France following early experiments by Henri Dupuy de Lôme, and, ...

'' and ''

Gustave Zédé Gustave Zédé was a French naval engineer and pioneering designer of submarines. Early life He was born in Paris in February 1825. After studying at the École Polytechnique in November 1843 he qualified in 1845 as a Marine engineer and went t ...

'' submarines. A model of ''Plongeur'' was displayed at the 1867 Exposition Universelle, where it was studied by Jules Verne, who used it as an inspiration and 3 years later published his novel ''

Twenty Thousand Leagues Under the Sea ''Twenty Thousand Leagues Under the Seas'' (french: Vingt mille lieues sous les mers) is a classic science fiction adventure novel by French writer Jules Verne. The novel was originally serialized from March 1869 through June 1870 in Pierre- ...

''.Notice at the Musée de la Marine,

After various experiments, the

French Navy The French Navy (french: Marine nationale, lit=National Navy), informally , is the maritime arm of the French Armed Forces and one of the five military service branches of France. It is among the largest and most powerful naval forces in t ...

struck the ship on 2 February 1872.

Conversion

The submarine was reactivated as an automotive water tanker, equipped with a compound 2-cylinder steam engine of 90 kW (120 hp), on 1 January 1873. She was assigned to the harbour of Rochefort. She was equipped with a new engine in 1898, transferred from a torpedo boat (Torpilleur No 74). In 1927, upon the closure of the arsenal at

, she was transferred to the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western Europe, Western and Southern Europe and Anatolia, on the south by North Africa ...

Toulon Toulon (, , ; oc, label= Provençal, Tolon , , ) is a city on the French Riviera and a large port on the Mediterranean coast, with a major naval base. Located in the Provence-Alpes-Côte d'Azur region, and the Provence province, Toulon is th ...

, where she was used to supply the 1st and 3rd squadrons with water. She was decommissioned on 25 December 1935, and sold for 25,143 ''francs'' to a M. Negai on 26 May 1937.

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