Plongeur

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The French submarine Plongeur, 1863.

Plongeur (French for "Diver") was a French submarine launched on April 16, 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.

1 Specifications
2 Operational history
3 Conversion
4 See also
5 External links

[edit] Specifications

Model of Plongeur at the Musée de la Marine, Paris.

The submarine was propelled by stored compressed air powering a reciprocating engine. The air was contained in 23 tanks holding air at 12.5 bar (1.25 MPa, 180 psi), taking up a huge amount of space (153 m³), and requiring the submarine to be of unprecedented size. The engine had a power of 80 hp (60 kW), and could propel the submarine for 5 nautical miles (9 km), at a speed of 4 knots (7.2 km/h).

Compressed air was also used to empty its ballast tanks, which had a volume of 53 m³. Ballast was 212 t, including a security ballast of 34 t.

The submarine was armed with a ram to break holes in the hull of enemy ships, and an electrically fired spar torpedo, fixed at the end of a pole.

The submarine was 43 m (140 feet) long and 420 long tons (426 t) in displacement.

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

A small lifeboat (8 x 1.7 m) was provided for the escape of the 12 men complement.

[edit] Operational history

Submarine Plongeur under tow by La Vigie.

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

On October 6, 1863, Plongeur made her first trials by sailing down the Charente river, towards the harbour of the Cabane Carrée.

On November 2, 1864, 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 and then to the harbour of La Rochelle (Bassin à flot).

On February 14, 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 February 18, 1864 Plongeur was towed to La Pallice and dived to 9 meters.

Stability problems due to its length limited the submarine to dives to a maximum depth of 10 metres. 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 and Gustave-Zédé submarine.

After various experiments, the French Navy struck the ship on February 2, 1872.

[edit] Conversion

Submarine Plongeur transformed as an automotive water tanker in the early 20th century.

The submarine was reactivated as an automotive water tanker, equipped with a compound 2 cylinder steam engine of 120 hp (90 kW), on January 1, 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 Rochefort, she was transferred to the Mediterranean at Toulon, where she was used to supply the 1st and 3rd squadrons with water.

She was decommissioned on December 25, 1935, and sold for 25,143 francs to a M. Negai on May 26, 1937.