The three Type UB I boats of the Constantinople Flotilla seem to have patrolled primarily in the Black Sea . UB @-@ 8 was transferred to the Bulgarian Navy in May 1916 , and UB @-@ 7 disappeared in the Black Sea in October 1916 , leaving UB @-@ 14 as the sole remaining German Type UB I in the flotilla ; she was surrendered at Sevastopol in November 1918 to French armies stationed there during the Russian Civil War .