Tobruk was a cargo ship which was built in 1941 as Empire Builder by William Gray & Company Ltd for the Ministry of War Transport (MoWT). On completion she was handed over to the Polish government-in-exile (along with four others; Narwik, Bałtyk, Białystok and Borysław, which in 1950 was renamed to Bytom) and renamed Tobruk. She was a member of a number of convoys during the Second World War. She was sold in 1951 to Polskie Linie Oceaniczne and served until 1967. She was scrapped in 1968. Description Empire Builder was built by William Gray & Sons Ltd, West Hartlepool. She was yard number 1123. Empire Builder was launched on 19 November 1941 and completed in January 1942. The ship was long, with a beam of and a depth of . She was propelled by a triple expansion steam engine which had cylinders of , and bore by stroke. The engine was built by Central Marine Engine Works, West Hartlepool. It could propel her at Empire Builder was listed on Lloyds Register as having a GRT of 7,090 and a NRT of 5,050. Tobruk was listed on Lloyds Register as having a GRT of 7,048 and a NRT of 4,977. Her DWT was 10,500. Career Empire Builder's port of registry was West Hartlepool. On completion, she was handed over to the Polish Government on 30 January 1942 and renamed Tobruk, after participation of Polish troops in defence of Tobruk. Her port of registry was changed to Gdynia. Tobruk was owned by the Polish government and operated under the management of Gdynia America Line, in charter of War Transport Administration. PQ 13 Convoy PQ 13 departed Loch Ewe on 10 March 1942 and arrived at Murmansk, Soviet Union on 31 March having lost six ships to enemy action. A further two were sunk at Murmansk after the convoy's arrival. Tobruk was damaged by enemy bombing at Murmansk, repairs took about six months to complete. Crew members were joking later that the convoy departed on the 13th day of the month, the trip lasted 13 days, and Tobruk had the thirteenth position in the convoy. QP 14 Convoy QP 14 departed Murmansk on 13 September 1942 and arrived at Loch Ewe on 26 September, having lost four ships to enemy action. Tobruk was carrying a cargo of Apatite. She departed Murmansk on 8 September bound for Archangelsk, from where she joined the