german type submarine boat german_imperial_navy german kaiserliche_marine world war sold bulgaria renamed bulgarian bulgarian submarine ordered october laid shipyard bremen november little metres length displaced tonnes long tons depending surfaced submerged carried torpedoes bow torpedo tubes armed deck mounted machine gun originally pair boats sent replace austrian pair sent dardanelles broken sections shipped rail march launched commissioned german_imperial_navy april austrians opted agreement briefly commissioning spent majority german career patrolling black_sea constantinople flotilla boat sank ships disguised british admiralty royal_navy battlecruiser operation october helped repel russian bombardment bulgaria submarine transferred commissioned ceremony attended prince bulgarian service submarine patrolled bulgarian black_sea coast encounters russian vessels occasions war ended submarine surrendered france february scrapped august july commander announced submarine discovered sea near town divers discovered manufacturer numbers according identity confirmed design construction german_army rapid advance north_sea coast earliest stages world war german_imperial_navy found suitable submarines operated narrow shallow seas flanders project design effort begun mid august produced type design small submarine shipped rail port operations quickly assembled constrained railroad size limitations design called boat metres long displacing tonnes long tons torpedo tubes boat initial submarines numbered ordered october shy months planning class began laid kiel december built metres long metres draft metres single brake horsepower cylinder diesel engine surface travel single shaft horsepower electric motor underwater travel attached single propeller shaft speeds knots mph surfaced knots mph submerged moderate speeds sail nautical miles surface nautical miles submerged batteries like boats class rated diving depth metres completely seconds armed centimeter torpedoes bow torpedo tubes outfitted single millimeter machine gun deck standard complement consisted officer thirteen enlisted men construction neared completion early march turkish leaders pleading german austro hungarian allies send submarines dardanelles help attack british french fleet pounding turkish positions germans induced austro hungarian navy german und send boats built boats promise replacements work complete yard rail shipment process shipping boat involved breaking submarine essentially knock kit boat broken approximately pieces loaded railway boats ready shipment main austrian naval base march despite fact austrian pair ready german engineers technicians accompanied german boats worked supervision head newly created boat special command german typically assembly process took weeks accordingly launched april german career trials assigned austrian number austrian commander german crew intent transferred wore civilian clothes austrian uniforms time dragged austrian ready eventually admiral head commitment overt hostility neighbor ally italy change heart austrians germany resolved retain send aid turks boat commissioned german_imperial_navy april command year old time boat commander commissioning boat temporarily joined flotilla german limited range able entire journey turkey towed austrian cruiser sms adriatic duo continued spotted french forces near slipped tow raced adriatic incident days departure running surface stern boat suddenly dropped watch officer conning tower able partially close hatch entire submarine slipped waves men water board submarine water continued pour hatch boat sinking stern ordered interior hatch control room sealed ballast tanks filled compressed air increase tactic returned surface boat diesel engines restarted missing crewmen watch officer recovered drowned came allied convoy near prospect hitting identified royal_navy battlecruiser allowed fully laden transport ships pass clear shot launched torpedoes stationary ship hit sending debris air unfortunately fact torpedoed british ocean liner participant admiralty plan disguise large liners royal_navy capital ships eventually sank outfitted wood canvas guns cement stones approximate profile tiger reports deaths sinking june submarine new constantinople flotilla german der division based constantinople present day istanbul despite german intentions use dardanelles ineffective hampered limited torpedo supply weak engines negotiating strong currents nearly impossible sent patrol black_sea active late july july sank second final ship ton russian ship august fired yards passed shallow draught submarine sighted outside net torpedoes fired missed hit net acute angle burst attack days later similar vessels unsuccessful september sent bulgaria patrol russian black_sea coast bulgaria joined central powers battleships aircraft seaplane carriers began attacks bulgarian coast october based time sortied disrupt bombardment able launch attacks launched torpedo russian battleship known missed despite lack success submarine presence cause russians break attacks withdraw early cruising black_sea germans good luck black_sea priority saw value submarines russian attacks began negotiations purchase bulgarian sailors practiced pair boats technicians sent kiel training german submarine school transfer took place reasons sources remained german flag bulgarian career acceptance renamed commissioning ceremony kept newspapers attended brother boarded submarine ceremonial voyage bulgarian summer palace located north bulgarian service submarine armed millimeter deck gun supplemented machine gun patrol bulgarian flag took place july sailed submarine reconnaissance coastal defense patrolled regular route route loop began went northward southward ended september encounter russian destroyers drove russian submarines occasions december helped turn russian sortie russian withdrawal world war activities greatly reduced end war surrendered french february towed scrapped august ships sunk damaged
SM UB-8