A forgotten French submarine predates Jules Verne

The Plongeur, launched in 1863 in Rochefort, was the first submarine in the world powered by a compressed air engine, designed by commander Bourgois and engineer Charles Brun. Despite its innovative propulsion system, the ship suffered from chronic instability when submerged, making it difficult to maneuver.

A real-life Nautilus before Verne’s novel

In 1863, when Jules Verne had not yet written the adventures of Captain Nemo, a real vessel set sail from Rochefort. Named the Plongeur, it represented an unprecedented feat: the first submarine in the world powered by a compressed air engine. Its origins date back to 1859, when commander Bourgois and engineer Charles Brun embarked on the design of this prototype.

Compressed air, a technical feat

What distinguished the Plongeur from all other projects of its time was its propulsion method. Where one might have expected a conventional steam engine, Charles Brun had bet on a motor powered by compressed air at 12 bars, a considerable pressure for the metallurgical techniques of the nineteenth century.

The fatal instability that condemned the Plongeur at sea

However, theory and practice would quickly clash with a much more capricious reality. As early as the first tests carried out in the dry dock of the Rochefort arsenal, a spectacular incident cast doubt on the reliability of the ship: a glass porthole shattered under pressure, forcing the crew to evacuate hastily.

From decommissioning to the water tank

After several years of tests and successive modifications, the French Navy finally gave up on this promising project. Too unstable at depth, the Plongeur was decommissioned in 1872, a victim of these stability problems that were never fully resolved despite the efforts made by its designers.

A pioneering submarine with an unexpected destiny

Once stripped of its secret equipment, its hull had a second life, far from its initial military ambitions: it was transformed into a freshwater tank ship for the warships stationed in Rochefort. A pioneering submarine, a technical ancestor of the Nautilus, ending its career transporting drinking water, a conversion that lasted until 1935.