French submarine Opale
Opale was one of six s built for the French Navy () in the first decade of the 20th century. Design and description. The "Émeraude" class were built as part of the French Navy's 1903 building program to a Maugas single-hull design. The submarines displaced surfaced and submerged. They had an overall length of , a beam of , and a draft of . They had an operational diving depth of . Their crew numbered 2 officers and 23 enlisted men. For surface running, the boats were powered by two Sautter-Harlé diesel engines, each driving one propeller shaft. When  submerged each propeller was driven by a 300-metric-horsepower electric motor. They could reach a maximum speed of on the surface and underwater. The "Émeraude" class had a surface endurance of at and a submerged endurance of at . The boats were armed with four internal torpedo tubes, two in the bow and two in the stern, for which they carried six torpedoes. Construction and career. "Opale" was laid down in October 1903 at the Arsenal de Cherbourg, launched on 27 November 1906 and commissioned on 19 December 1908.