"Sydney", with 7 RAR on board, and the destroyer escort "Yarra" departed from Sydney for the sixteenth voyage on 16 February 1970. They arrived in Vietnam on 27 February, with "Sydney" embarking 5 RAR for the voyage to Fremantle, where they arrived on 5 March. On 16 April, "Sydney" was one of 45 vessels from 13 nations assembled in Sydney Harbour to celebrate the Australian Bicentenary, marking James Cook's discovery of the east coast of Australia. Later that month, a visit to Portland, Victoria coincided with the Bicentenary Royal Tour of Queen Elizabeth II and the Duke of Edinburgh. "Sydney" sailed from Fremantle on 21 October on the seventeenth voyage to Vietnam. The troopship met the destroyer "Vendetta" off Manila, and reached Vietnam on 31 October, where 2 RAR was offloaded and 8 RAR embarked. The two ships departed a day later, with "Sydney" reaching Brisbane on 12 November. At the start of February 1971, the troopship visited Hobart to serve as the flagship of the Royal Hobart Regatta, before she sailed to Adelaide, embarked 3 RAR, then departed on her eighteenth Vietnam voyage on 15 February. "Sydney" met the destroyer escort "Yarra" en route, with both ships reaching Vũng Tàu on 25 February, where 7 RAR boarded for the return voyage. On 2 March, two days before reaching Fremantle, the ashes of Rear Admiral Harold Farncomb were scattered from "Sydney".