 The German submarines in the Black Sea accomplished little , sinking only six ships between August 1916 and the end of the year . UB @-@ 42 sank half of the six in September and October . On 3 September , Wernicke and UB @-@ 42 achieved their first success when they sank the Russian transport Peter Darcy in the Black Sea . The 731 @-@ ton ship was headed from Constantza to Odessa when torpedoed by UB @-@ 42 . The 150 @-@ ton Russian vessel St. Nikolei was sunk at the entrance to Karkinit Bay on 5 October , and the 2 @,@ 891 @-@ ton Czarita was sunk two weeks later off Cape Midia . 
