SM UB - 46 SM " UB - 46 " was a Type UB II submarine or U - boat for the German Imperial Navy ( ) during World War I . " UB - 46 " operated in the Mediterranean and the Black Seas , and was sunk by a mine in December 1916 . " UB - 46 " was ordered in July 1915 and was laid down at the AG Weser shipyard in Bremen in September . " UB - 46 " 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 tube s and had an deck gun . As part of a group of six submarines selected for Mediterranean service , " UB - 46 " was broken into railcar sized components and shipped to Pola where she was assembled and launched in May 1916 , and commissioned in June . In early December 1916 , during the submarine ' s fifth patrol , " UB - 46 " struck a mine in the Black Sea a short distance from the north entrance to the Bosphorus and sank with all hands . In her six - month career , " UB - 46 " sank four ships of . 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 much fuel . To contain all of these changes the hull was larger , and the surface and submerged displacement was more than double that of the UB I boats . The Imperial German Navy ordered " UB - 46 " from AG Weser on 31 July 1915 as one of a series of six UB II boats ( numbered from to ) . " UB - 46 " was long and abeam . She had a single hull with saddle tank s and had a draft of when surfaced . She displaced while submerged but only on the surface . The submarine was equipped with twin diesel engines and twin electric motors — for surfaced and submerged running , respectively — that drove twin propeller shafts . " UB - 46 " had a surface speed of up to and could go as fast as while underwater . The U - boat could carry up to of diesel fuel , giving her a range of 6 , 940 nautical miles at 5 knots ( 12 , 850 km at 9 . 3 km / h ) . Her electric motors and batteries provided a range of 45 nautical miles at 4 knots ( 83 km at 7 . 4 km / h ) while submerged . " UB - 46 " was equipped with two bow torpedo tube s and could carry four torpedo es . The U - boat was also armed with a 5 cm KL / 40 ( 2 . 0 in ) deck gun . " UB - 46 " was laid down by AG Weser at its Bremen shipyard on 4 September 1915 . As one of six U - boats selected for service in the Mediterranean while under construction , " UB - 46 " was broken into railcar - sized components and shipped overland to the Austro - Hungarian port of Pola . Shipyard workers from Weser assembled the boat and her five sisters at Pola , where she was launched on 17 June . Service career . SM " UB - 46 " was commissioned into the German Imperial Navy on 12 June 1916 under the command of " Oberleutnant zur See " Cäsar Bauer . " UB - 46 " , Bauer ' s third U - boat command , was assigned to the Navy ' s Pola Flotilla ( ) . Although the flotilla was based in Pola , the site of the main Austro - Hungarian Navy base , boats of the flotilla operated out of the Austro - Hungarian base at Cattaro which was located farther south and closer to the Mediterranean . German U - boats typically returned to Pola only for repairs . After a month at the helm of " UB - 46 " , Bauer was promoted to " Kapitänleutnant " . On 2 August , Bauer achieved his first success in command of " UB - 46 " when the Japanese steamer " Kohina Maru " was sunk off Alexandria just short of her destination of Port Said . A week later the U - boat sank the Greek sailing vessel " Basileios " which was headed back to the Adriatic from Egypt . On 2 October , Bauer torpedoed " Huntsfall " which was carrying hay to Salonica , and took the ship ' s master prisoner . The British steamer was the largest ship sunk by " UB - 46 " . After Germany ' s conquest of Romania ( see " Romania during World War I " ) , the German Imperial Navy had sufficient fuel oil for submarines located in the Black Sea . " UB - 46 " and three of her sister ships in the Pola Flotilla were ordered to Constantinople and , en route , had to navigate through the Dardanelles , which had been heavily mined by the Allies in the middle of 1916 . " UB - 46 " joined the Constantinople Flotilla ( ) on 7 October . The German submarines in the Black Sea accomplished little , sinking only six ships between August and the end of the year . " UB - 46 " sank one of the six ships when she sent down the 116 - ton Russian ship " Melanie " north of Cape Tarkhan on 7 November . " Melanie " was the last ship sunk by " UB - 46 " . By early December , " UB - 46 " was based out of Varna , Bulgaria . Fate . On 7 December 1916 , the stern of " UB - 46 " struck a Russian mine off the shore of the Turkish village of Akpınar , approximately north - west of the entrance to the Bosphorus . The vessel ' s entire complement ( reported by Helgason as 20 ) perished in the sinking . A portion of the wreck comprising the forward section of the torpedo room and battery compartment was located in 1993 during coal extraction operations and was salvaged by the Turkish navy ; the remainder of the vessel could not be located . It was put on display in an outdoor exhibit at the Turkish Naval Museum in Istanbul . The wreckage was transferred to the Dardanelles Naval Museum at Çanakkale in 2008 , where the remains of the vessel are currently on display .