German Type IX submarine The Type IX U - boat was designed by Germany in 1935 and 1936 as a large ocean - going submarine for sustained operations far from the home support facilities . Type IX boats were briefly used for patrols off the eastern United States in an attempt to disrupt the stream of troops and supplies bound for Europe . The extended range came at the cost of longer dive times and decreased maneuverability , which is why the smaller Type VII was produced in greater numbers and used for the bulk of operations . It was derived from the Type IA , and appeared in various sub - types . Type IXs had six torpedo tubes ; four at the bow and two at the stern . They carried six reloads internally and had five external torpedo containers ( three at the stern and two at the bow ) which stored ten additional torpedoes . The total of 22 torpedoes allowed U - boat commanders to follow a convoy and strike night after night . As mine - layers they could carry 44 TMA or 66 TMB mine s , but many of the IXC boats were not fitted for mine operations . Secondary armament was provided by one large Utof 105 / 45 gun with about 110 rounds . Anti - aircraft armament differed throughout the war . They had two periscopes in the tower . Types IXA and IXB had an additional periscope in the control room , which was removed in Type IXC and afterward . Type IXA . List of Type IXA submarines . AG Weser of Bremen built eight Type IXA U - boats . Type IXB . Type IXB was an improved model with an increased range . It was the most successful version overall with each boat averaging a total of over 100 , 000 tonnes sunk . Notable IXB boats included commanded by Reinhard Hardegen , which opened up the attack in the US waters in early 1942 known as Operation Drumbeat , and operating off Freetown , Sierra Leone under the command of Günther Hessler , which had the most successful single mission of the war ever with close to 100 , 000 tonnes sunk . List of Type IXB submarines . AG Weser of Bremen built 14 Type IXB U - boats . Type IXC . Type IXC was a further refinement of the class with storage for an additional 43 tonnes of fuel , increasing the boat ' s range . This series omitted the control room periscope leaving the boats with two tower scopes . As mine - layers they could carry 44 TMA or 66 TMB mines , though through and through ( 35 boats ) , were not fitted for mine operations . One IXC carries the distinction of being the only U - boat sunk in the Gulf of Mexico , . " U - 505 " survives at the Museum of Science and Industry in Chicago , and as of 2005 has been completely renovated . List of Type IXC submarines . AG Weser and Seebeckwerft of Bremen , and Deutsche Werft of Hamburg built 54 Type IXC submarines . Type IXC / 40 . Type IXC / 40 was an improved Type IXC with slightly increased range and surfaced speed . The remains of are on display at Woodside Ferry Terminal , Birkenhead . List of Type IXC / 40 submarines . AG Weser and Seebeckwerft of Bremen , and Deutsche Werft of Hamburg , built 87 of this type . Type IXD . Type IXD was significantly longer and heavier than the IXC / 40 . It was faster than the IXC but at the cost of slightly reduced range . They had three pairs of Daimler Benz diesels : two pairs for cruise and one for high speed or battery recharge . There were three variants : the IXD1 , IXD2 and IXD / 42 . The IXD1 had unreliable engines and they were later converted for use in surface transport vessels . The IXD2 comprised most of the class and had a range of over 23 , 700 miles . The IXD / 42 , was almost identical but with more engine power ( 5 , 400 ehp instead of 4 , 400 ) . In 1943 and 1944 the torpedo tubes were removed from a number of IXD boats converted for transport use . In their new role they could transport 252 tonnes of cargo . List of Type IXD submarines . AG Weser of Bremen built 30 Type IXD U - boats . Several Type IXD / 42 U - boats were contracted to be built AG Weser of Bremen , but only two were commissioned . They were :