The French submarine Diane was the name boat of her class of two submarines built for the French Navy during World War I. Completed in 1917, the boat suffered an internal explosion in the Bay of Biscay off La Pallice, France, and sank with the loss of her entire crew of 43 in February 1918.Roberts, p. 453
Design and description The Diane class was built as part of the French Navy's 1912 building programSmigielski, p. 211 as scaled down versions of adapted to use diesel engines. The boats displaced surfaced and submerged. They had an overall length of , a beam of , and a draft of . Their crew numbered 34 officers and crewmen.
For surface running, the Diane-class boats were powered by two diesel engines, each driving one propeller shaft. The engines for Diane had been ordered from Chaléassière in 1913, but the company proved unable to deliver them in a timely manner and a pair of Vickers eight-cylinder, four-cycle engines had to be purchased from Britain in 1915. This reduced the boat's speed from the designed to . When submerged each shaft was driven by a electric motor. The designed speed underwater was , but the boats only reached during their sea trials. The Dianes had a maximum fuel capacity of which gave them a surface endurance of at . Their designed submerged endurance was at , but sea trials showed that it fell short of that figure at .
The Diane class was armed with a total of ten torpedoes. Four of these were positioned in the bow; two in internal torpedo tubes in the bow angled outwards three and a half degrees and two in external tubes above them angled outwards nine degrees. Four more were located in four external rotating launchers amidships, two on each broadside; one pair each fore and aft of the conning tower that could traverse 130 degrees to the side of the boats. The last pair were in external tubes in the stern aimed directly aft. While the boats were under construction in 1915 a Mle 1897 gun with high-angle capacity was ordered to be installed aft of the conning tower. Daphné is known to have received one, but it is uncertain if Diane did.Garier 2000, p. 118
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