The government signed a contract on the weekend to buy the 6500 tonne Skandi Bergen for $130 million.
Mr Smith said the offshore support vessel would complement the existing heavy amphibious vessels, HMAS Choules and HMAS Tobruk.
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"This is a very effective and efficient and value for money purchase so far as the Commonwealth is concerned," he said.
"This now completes the work that we have been doing on our heavy amphibious lift capability since February last year when in the face of Cyclone Yasi, very regrettably, no heavy amphibious lift capability was available."
Mr Smith said the Skandi Bergen would be ready for service about mid-year.
The vessel will ensure defence has the full capability to conduct humanitarian and disaster relief operations until the arrival of the two large landing helicopter dock vessels (LHD) in mid-decade.
It then will be transferred to Customs and Border Protection.
Defence Minister Stephen Smith says the latest C-17, costing $280 million and to be delivered by the end of the year, would effectively double the number of C-17s available for operations at any time from two to four aircraft.
The government also has given the go-ahead for $15.5 million to be spent on long lead items for the next batch of 101 Bushmaster armoured vehicles.
