▁ 2 8 ▁July ▁ 1 9 1 7 ▁at ▁. ▁Th ir teen ▁crew ▁members ▁died ▁in ▁the ▁event . ▁ ▁Design ▁A ▁German ▁Type ▁U B ▁II ▁sub marine , ▁U B - 2 0 ▁had ▁a ▁disp lacement ▁of ▁ ▁when ▁at ▁the ▁surface ▁and ▁ ▁while ▁sub mer ged . ▁She ▁had ▁a ▁total ▁length ▁of ▁, ▁a ▁beam ▁of ▁, ▁and ▁a ▁dra ug ht ▁of ▁. ▁The ▁sub marine ▁was ▁power ed ▁by ▁two ▁Kör ting ▁six - cy l inder , ▁four - stroke ▁dies el ▁engines ▁each ▁producing ▁a ▁total ▁, ▁a ▁S iem ens - Sch uck ert ▁electric ▁motor ▁producing ▁, ▁and ▁one ▁prop eller ▁sh aft . ▁She ▁was ▁capable ▁of ▁operating ▁at ▁depth s ▁of ▁up ▁to ▁. ▁ ▁The ▁sub marine ▁had ▁a ▁maximum ▁surface ▁speed ▁of ▁ ▁and ▁a ▁maximum ▁sub mer ged ▁speed ▁of ▁. ▁When ▁sub mer ged , ▁she ▁could ▁operate ▁for ▁ ▁at ▁; ▁when ▁sur fac ed , ▁she ▁could ▁travel ▁ ▁at ▁. ▁U B - 2 0 ▁was ▁fitted ▁with ▁two ▁ ▁tor ped o ▁tub es , ▁four ▁tor ped o es , ▁and ▁one ▁ ▁SK ▁L / 4 0 ▁deck ▁gun . ▁She ▁had ▁a ▁complement ▁of ▁twenty - three ▁crew ▁members ▁and ▁two ▁officers ▁and ▁a ▁ 4 5 - second ▁d ive ▁time . ▁ ▁Sum mary ▁of ▁ra iding ▁history ▁ ▁References ▁ ▁Notes ▁ ▁Cit ations ▁ ▁Bibli ography ▁▁▁▁▁ ▁Category : G erman ▁Type