SM UB-47 was a Type UB II submarine or U-boat for the German Imperial Navy () during World War I. UB-47 was sold to the Austro-Hungarian Navy ( or ) during the war. In Austro-Hungarian service the B was dropped from her name and she was known as SM U-47 or U-XLVII as a member of the Austro-Hungarian U-43 class. UB-47 was ordered in July 1915 and was laid down at the AG Weser shipyard in Bremen in September. UB-47 was a little more than in length and displaced between , depending on whether surfaced or submerged. She was equipped to carry a complement of four torpedoes for her two bow torpedo tubes and had an deck gun. As part of a group of six submarines selected for Mediterranean service, UB-47 was broken into railcar sized components and shipped to Pola where she was assembled and launched in June 1916, and commissioned in July. Over the next year the U-boat sank twenty-two ships, which included the French battleship and two Cunard Line steamers in use as troopships, and . The German Imperial Navy was having difficulties in finding trained submarine crews and offered to sell UB-47 and a sister boat to the Austro-Hungarian Navy. After the terms were agreed to in June 1917, both boats were handed over at Pola. When commissioned into the Austro-Hungarian Navy, the B in her designation was dropped so that she became U-47 or U-XLVII. She sank an additional three ships in Austro-Hungarian service through the end of the war. U-47 was ceded to France as a war reparation in 1920 and broken at Bizerta that same year. Design and construction The German UB II design improved upon the design of the UB I boats, which had been ordered in September 1914. In service, the UB I boats were found to be too small and too slow. A major problem was that, because they had a single propeller shaft/engine combo, if either component failed, the U-boat became almost totally disabled. To rectify this flaw, the UB II boats featured twin propeller shafts and twin engines (one shaft for each engine), which also increased the U-boat's top speed. The new design also included more powerful batteries, larger torpedo tubes, and a deck gun. As a UB II boat, U-47 could also carry twice the torpedo load of her UB I counterparts, and nearly ten times as