german type submarine type class submarines boats operated german_imperial_navy german kaiserliche_marine world war class alternately referred class type class built design class boats sold beginning world war thought impossible submarines reach mediterranean delivery austria-hungary austro hungarian navy evaluating submarines foreign designs selected type design design class boats numbered designed feet long displace tonnes long tons surfaced submerged armed torpedo tubes deck gun propulsion design called twin diesel engines surface running twin electric motors movement ordered boats february construction began boats november outbreak world war august austro hungarian navy convinced delivery unfinished submarines mediterranean gibraltar impossible result sold boats imperial_german_navy november german_navy assigned numbers submarines redesigned reconstructed specifications changes included larger deck gun increased displacement boats tonnes long tons surfaced nearly tonnes long tons submerged boats saw active service sank ships sunk days war patrol march successes boats disappeared remaining boats surrendered united_kingdom broken background allowing navies countries pioneer submarine developments ordered german produce submarine design navy rejected january design designs submitted public competition instead opted order submarines designs competitive evaluation based trials results determined characteristics generation austro hungarian submarines looking double submarine tonnes long tons displacement diesel propulsion wanted surface speed knots mph boat armed torpedo tubes selected design known type class type design submitted primarily lower cost navy ordered boats february design class seen improved version class design designed boats displace tonnes long tons surface tonnes long tons submerged doubled boats feet long overall beam feet inches draft feet inches austrian specifications called shafts twin diesel engines metric horsepower total surface running knots mph twin electric motors shp total maximum knots mph submerged boats designed torpedo tubes located bow stern boats armament include single deck gun construction austro hungarian navy february order boats laid november laid end december final boats begun february construction boats slated complete months submarines complete world war began august boats construction kiel austrians convinced impossible delivery boats need towed mediterranean past gibraltar british territory result boats class transferred imperial_german_navy november advance payment million returned awarded type known purchase boats assigned numbers class known type imperial_german_navy submarines redesigned reconstructed german standards increased surface displacement tonnes long tons submerged tonnes long tons torpedo load increased deck gun upgraded gun originally specified launched april class followed weeks boat hitting water july boats completed commissioned imperial_german_navy july september service career boats class saw active service boat wartime successes sank tons allied shipping sunk british ship march boat class lost war lost july september respectively survived war surrendered united_kingdom november broken boats class lead boat class laid november yard number kiel launched april commissioned july command war sank ships totaling gross register tons grt largest ships sank british grt grt sunk heard september reported position north_sea fate officially unknown british records suggest struck sunk destroyers borne german records laid november yard number kiel launched commissioned august command sank total ships grt damaged grt surrendered united_kingdom november broken laid december yard number kiel launched june commissioned august command days war patrol encountered british ship ship number sunk hands sank ships brief service career laid february yard number kiel launched june commissioned september command service career sank ships combined gross register largest ton armed merchant cruiser heard july reported coast norway fate officially unknown british reports credit sinking destroyer dates german records support claim laid february yard number kiel launched july commissioned september command war sank warship british sloop civilian ships totaling grt civilian ships grt largest ships hit boats war damaged ships grt surrendered british november broken
German Type U 66 submarine