U - 1 - class submarine ( Austria - Hungary ) The " U - 1 " class was a class of two submarine s or U - boats built for and operated by the Austro - Hungarian Navy ( ) . The " U - 1 " - class boats were built to an American design at the navy yard in Pola . The class was a part of the Austro - Hungarian Navy ' s efforts to competitively evaluate three foreign submarine designs . The two " U - 1 " - class boats , both launched in 1909 , were long and as built were each powered by two gasoline engines while surfaced , and two electric motors when submerged . Neither boat was operational at the beginning of World War I because both were in drydock awaiting replacement diesel engines for their problematic gasoline engines . Beginning in 1915 , both boats conducted reconnaissance cruises out of either Trieste or Pola until declared obsolete in early 1918 . Both remained in service as a training boats at the submarine base on Brioni , but each was at Pola at the end of the war . They were ceded to Italy as war reparations in 1920 and scrapped at Pola . Neither submarine sank any ships during the war . Design and construction . In 1904 , after allowing the navies of other countries to pioneer submarine developments , the Austro - Hungarian Navy ordered the Austrian Naval Technical Committee ( MTK ) to produce a submarine design . The January 1905 design developed by the MTK and other designs submitted by the public as part of a design competition were all rejected by the Navy as impracticable . They instead opted to order two submarines each of designs by Simon Lake , Germaniawerft , and John Philip Holland for a competitive evaluation . The two Lake - designed submarines comprised the " U - 1 " class . The Navy ordered plans for the building of two boats — designated " U - 1 " and " U - 2 " — from the Lake Torpedo Boat Company of Bridgeport , Connecticut , in 1906 . The " U - 1 " - class design had several features typical of Lake ' s designs , including a diving chamber under the bow and two variable pitch propellers . Lake ' s design also called for two retractable wheels that , in theory , could allow travel over the seabed . The design also placed the diving tank s above the waterline of the single , cylindrical hull , which necessitated a heavy ballast keel for vertical stability . The propulsion system for the " U - 1 " class consisted of two gasoline engines for surface running and two electric motors for running while submerged . For underwater steering and maneuverability , the design featured four pairs of diving plane s . The boats were long by abeam and had a draft of . As designed , each boat displaced surfaced and submerged . Both of the submarines had three torpedo tubes — two in the bow , one in the stern — and could carry up to five torpedoes , but typically carried three . Each submarine was also armed with a deck gun . " U - 1 " and " U - 2 " were laid down in July 1907 at the navy yard at Pola , and were launched in February and April 1909 , respectively . Service career . Upon completion of the two boats , the Austro - Hungarian Navy evaluated the " U - 1 " class in trials through 1910 . During the trials , technical problems with the gasoline engines were revealed . Exhaust fumes and gasoline vapors frequently poisoned the air inside the boats and the engines themselves were not able reach the contracted speed . Because of the problems , the Austro - Hungarian Navy considered the engines to be unsuitable for wartime use and paid only for the hulls and armament of the two " U - 1 " boats . While replacement diesel engines were ordered from the Austrian firm " Maschinenfabrik " Leobersdorf , they agreed to a lease of the gasoline engines at a fee of US $ 4 , 544 annually . In order to dive , the diving tanks , located above the waterline , had to be flooded by pumps , which took over 14½ minutes in early tests , but which was later reduced to 8 minutes . The maximum diving depth was set at when the hulls began to show signs of stress at that depth . The four pairs of diving planes gave the boats exceptional underwater handling , and , when the boats were properly trimmed and balanced , the boats could be held within of the desired depth . Other tests proved the underwater wheels to be useless . The " U - 1 " class boats outperformed the " U - 3 " ( Germaniawerft ) and " U - 5 " ( Holland ) classes in both diving and steering capabilities in the Austro - Hungarian Navy evaluations . Both boats were officially commissioned into the Austro - Hungarian Navy in 1911 — " U - 1 " in April , " U - 2 " in June — and served as training boats , each making as many as ten training cruises a month . At the outbreak of World War I , " U - 1 " and " U - 2 " were both in drydock awaiting the installation of their new diesel engines . To accommodate the new engines , the boats were lengthened by about . These changes lowered the surface displacement to but increased the submerged displacement to . From 1915 , both boats conducted reconnaissance cruises out of either Trieste or Pola . In January 1918 , the boats were declared obsolete , but remained in service as training boats at the submarine base at Brioni , but at the war ' s end both boats were in Pola , After the war , both boats were ceded to Italy as war reparations and scrapped . Neither boat sank any ships during the war . Class members . SM " U - 1 " . " U - 1 " was laid down at the navy yard at Pola in July 1907 , launched in February 1909 , and underwent trials throughout 1910 . She was commissioned in April 1911 and served as a training boat through 1914 . Her periscope was damaged when she was accidentally rammed by an Austro - Hungarian cruiser in January 1914 . At the beginning of World War I , " U - 1 " was not operational because she was in drydock awaiting new batteries and replacement diesel engines . When the engine swap had been completed , " U - 1 " served as a training boat for the Austro - Hungarian Navy through October 1915 . From November that same year she conducted reconnaissance cruises out of Trieste and Pola until she was declared obsolete in early 1918 . " U - 1 " remained in service as a training boat at the submarine base on Brioni , but was at Pola at the end of the war . She was awarded to Italy as a war reparation in 1920 and scrapped at Pola . " U - 1 " did not sink any ships during the war . SM " U - 2 " . SM " U - 2 " was laid down at the navy yard at Pola in July 1907 , launched in April 1909 , and underwent trials through 1910 . She was commissioned in June 1911 and served as a training boat through 1914 . At the beginning of World War I , " U - 2 " was not operational because she was in drydock awaiting replacement diesel engines . With her new engines and a new conning tower installed by June 1915 , " U - 2 " conducted reconnaissance cruises out of Trieste but was declared obsolete in early 1918 . " U - 2 " remained in service as a training boat at the submarine base on Brioni , but was at Pola at the end of the war . She was ceded to Italy as a war reparation in 1920 and scrapped at Pola . " U - 2 " sank no ships during the war .