Tobruk was a 7,090 GRT cargo ship which was built in 1941 as Empire Builder by William Gray & Company Ltd for the Ministry of War Transport (MoWT).

Empire Builder was built by William Gray & Sons Ltd, West Hartlepool.

[3] It could propel her at 9.5 knots (17.6 km/h)[4] Empire Builder was listed on Lloyds Register as having a GRT of 7,090 and a NRT of 5,050.

[5] Tobruk was owned by the Polish government and operated under the management of Gdynia America Line, in charter of War Transport Administration.

[8] She was hit by one bomb, which luckily pierced a deck and went out through a board, exploding in a water, instead of in a cargo hold with explosives.

[8] However, on 3 April Tobruk was sunk by a pier in Murmansk by enemy bomb, which flooded stern holds.

[8] Thanks to a dedication of the crew, the ship was kept partly afloat for several months, and provisionally repaired in Murmansk dock by September only.

[11] Convoy SL 178 departed Freetown, Sierra Leone on 25 November 1944 and arrived at Liverpool on 15 December.

[16] In June 1967 Tobruk was transferred to other Polish state-owned operator, Polska Żegluga Morska (Polsteam), but was stricken already in November 1967.