Sovjet floating dock sections underway to Petropavlovsk according to the Australia Station Intelligence Summary dated 1 June 1955

An item reported that the Queenborough sighted two Soviet floating dock sections which were reported in A.S.I.S. May 1955 and which had passed since then Singapore bound for Petropavlovsk coming from Odessa, Ukraine.

Source

Website Royal Australian Navy, Sea Power Centre.