Le Sous-marin Le Plongeur - The first French Submarine; 1863

Le sous-marin Français Le Plongeur, 1863

In yesterday's post about French Naval Architect Dupuy de Lôme, Louis la Vache wrote that up until the Nazi take-over of France in World War II, the French built the world's finest sous-marins. France had long been a leader in advancing the technology of submarines. For example, Le Plongeur, "The Diver," launched on le 16 avril 1863, was the world's first submarine not to be propelled by human power.

The idea of traveling underneath the ocean waters inside a contained vessel has been around for centuries. Records of submarine ideology go back in history to man’s earliest writings. Legend says Alexander the Great ventured below the waters of the Aegean Sea inside a glass barrel around 333 B.C. He is reported to have seen whales and deep-sea life on his underwater journey. The ancient Athenians used divers in secret military operations. Heroduotus (460 B.C.), Aristotle (332 B.C.) and Pliny (77 A.D.) mention attempts by others to build submersibles.

The next record of a submarine came more than 1900 years later. In 1578 A.D., British naval officer William Bourne described a wooden frame vessel enclosed in waterproof leather, which could be rowed underwater. Bourne's creation was never realized.

In 1620, Cornelius Van Drebbel, a Dutch doctor, designed a submarine, which was also rowed underwater. The model was a greased, leather-covered rowboat that carried 12 oarsmen. Tubes to the surface provided air to the boat, which was bound by waterproof leather, allowing it to travel underwater for several hours. His boat was successfully tested in the Thames River and traveled at depths close to 15 feet (4.6 metres). It is said England's King James I rode in one of Van Drebbel's submarines to prove its safety. The British navy was not interested in the craft.

In 1690, Edmund Halley [of comet fame] patented a diving bell which was connected by a pipe to weighted barrels of air that could be replenished from the surface. Both barrel and bell, the latter with men in it, were lowered to depth; dives to over 60 feet (18.3 metres) for 90 minutes were recorded. Diving bells were shown to be practicable devices.

In 1715, Englishman John Lethbridge built a "diving engine", an oak cylinder which was reinforced with iron hoops and had a glass viewing port. Inside this device, a diver could stay submerged for 30 minutes at 60 feet (18. 3 metres), while protruding his arms into the water for salvage work. Water was kept out of the suit by means of greased leather cuffs, which seal around the operator's arms. The diving engine was said to be used successfully for many years.

Several other industrious inventors attempted to build crafts for underwater travel, but none were used for military efforts until the American Revolution. Between the American Revolution and the launching of le Plongeur were several attempts by the navies of the world to develop a truly workable submarine, but there were no real successes.

In the efforts to conquer the sea’s depths, submarines throughout history were propelled by a diversity of mechanisms. Pioneer submarine builders tried oars, sails, treadles, cranks, clockwork, chemicals, springs, and hand-cranked screws. Thus le Plongeur, propelled by stored compressed air moving a reciprocating engine was a real breakthrough. The compressed air was contained in 23 tanks holding air at 12.5 bar (180 psi), taking up a huge amount of space (153 cubic metres), and requiring the submarine to be of unprecedented size. The engine developed 80 horsepower, and could propel the submarine for 5 miles, at a speed of 4 knots. (For you landlubbers, Louis la Vache reminds you that a knot equals 1.25 miles per hour. Thus 4 knots = 5 miles-per-hour.)

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

The submarine was armed with a ram to hole the hull of enemy ships, and an electrically fired torpedo, fixed at the end of a pole. The submarine was 43 metres (140 feet) long and 420 tons (378 tonnes) 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 metres) was provided for the 12 man crew. Captain Simon Bourgeois, who made the plans, and naval constructor Charles Brun began working on the design in 1859 at Rochefort.

Sous-marinle Plongeur under tug.

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

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

On le 2 novembre 1864, Plongeur was tugged toward Port de Barques where her first submarine trials were planned. Because of poor weather conditions, the submarine was eventually tugged to La Pallice and then to the French Navy's Bassin à flot, fleet basin harbour, at La Rochelle.

On le 14 fevrier 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 quai. The trials were stopped. On le 18 fevrier 1864, Plongeur was tugged to La Pallice and she dove to 9 meters, 29.5 feet.

Stability problems due to its length limited the submarine to dives of a maximum depth of 10 metres. The front of the submarine tended to dive first, hitting the bottom, and 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 submarines. After various experiments, the French Navy eventually struck le Plongeur from its list of active ships on le 2 fevrier 1872.

Submarine Plongeur transformed as a water tanker seen here in the early XX ème siecle.
The submarine was reactivated as a water tanker, equipped with a compound 2 cylinder steam engine of 120 horsepower, on le 1 janvier 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 French Naval Base at Toulon on the Mediterranean where she was used to supply the 1st and 3rd naval squadrons with water.

She was de-commisionned on le 25 décembre 1935, and sold for 25,143 francs to a M.Negai on le 26 mai 1937. Stability problems limited Plongeur's use for which she was intended, but for such an experimental ship, she had a surprisingly long life. Not only was she the world's first sous-marin not to be powered by her crew, but her use of high-pressure compressed air to regulate her tanks became an integral part of submarine technology, still used today .

More Reading:

Louis la Vache regrets that he was unable to locate any titles en anglais about le marin Français et le sous-marin Plongeur. However in place of that, he offers the following titles in English:


Twenty Thousand Leagues Under the Sea (Barnes & Noble Classics Series)

Raising the Hunley: The Remarkable History and Recovery of the Lost Confederate Submarine

Torpedo Junction: U-Boat War off America's East Coast, 1942