French submarine Charles Brun

Charles Brun was one of four experimental submarines ordered for the French Navy in 1906. Each boat was built to a different design and Charles Brun was intended to test a novel powerplant. Although the shore-based prototype installation was successful, it was a failure when evaluated aboard the submarine, and the boat was never commissioned for active service. Her hull was stripped of its equipment and was used to test a floating drydock in 1914. During the First World War, the hull was ordered to be converted into a water tank in 1916, but it is not certain if this was actually done before it was sold for scrap in 1920.