 UB @-@ 42 was laid down on 3 September 1915 . As one of six U @-@ boats selected for service in the Mediterranean while under construction , UB @-@ 42 was broken into railcar @-@ sized components and shipped overland to the Austro @-@ Hungarian port of Pola . Shipyard workers from Weser assembled the boat and her five sisters at Pola , where she was launched on 4 March 1916 . 
