With the winning bidder for Australia's next fleet of submarines announced as French company DCNS, attention has turned to how it will meet Australia's requirement for a long-range, high-endurance war machine.

Key points: Submarines must accommodate crew for lengthy periods

Submarines must accommodate crew for lengthy periods American weaponry creates need for a 'three-way' collaboration

American weaponry creates need for a 'three-way' collaboration Chance for Australian industry to get involved in Shortfin Barracuda design

Australian Strategic Policy Institute Defence and Strategy Program director Andrew Davies said none of the off-the-shelf submarines that bidders drew their designs from had the range capability required by Australia.

The country's isolation and its need to patrol massive swathes of ocean waters mean it must have a fleet of submarines that can stay at sea for long periods of time.

"High endurance is not just a matter of fuel and payload," Mr Davies said.

"It's a matter of having enough people on board to do all the jobs that need to be done, without tiring out the crew."

Australia's existing Collins class submarines require a crew of about 58 people per boat and the Navy has reportedly struggled to maintain crew numbers during some periods.

Because of the long range that Australia's submarines will be required to travel, even if a boat requires a smaller crew - such as the 33 required to crew the Class 216 model unsuccessfully pitched by Germany company ThyssenKrupp Marine Systems (TKMS) - a large crew is still required for staff rotations.

"The question is, how habitable can you make the submarines, and how automated can you make them to reduce the stress on the crews in terms of the jobs they have to perform?" Mr Davies said.

He said the design for French company DCNS, the Shortfin Barracuda Block 1A model, was essentially a scaled down version of its larger nuclear submarine.

"In terms of habitability ... it should be pretty good. You're starting from a design that has more space and more power than we'll have in our boat, but we should be able to reach those accommodations fairly quickly," Mr Davies said.

He said the Japanese had an interesting problem to solve in that "the average Japanese sailor is physically smaller than the average Australian sailor".

The existing Soryu class submarine upon which it based its Australian pitch offered accommodation spaces too small for Australians.

American weaponry a must for Australian subs

The submarines will also be designed to accommodate American combat systems and weapons.

A concept design of the Shortfin Barracuda Block 1A submerged in deep water. ( Supplied: DCNS )

"The American weapon and combat system in the Collins has been built into what's essentially a Swedish design," Mr Davies said.

"It will be a three-way collaboration, Australia, the United States and whoever we pick as a provider.

"In fact, the Mark 84 torpedo is a weapon that's been a joint development of Australia and the United States and we'd like to stay in that program and keep that weapon. Whoever builds the submarines is going to have to incorporate that and that shouldn't be a problem."

Engineers Australia defence spokesperson Greg Walters said the combat system could be considered the "brains of the submarine and controls how the submarine operates the weapon systems and communications".

"It is extremely complex and will require a great many highly skilled and qualified people to integrate it into the new submarine and to maintain the system in Australia throughout the life of the fleet," he said.

"At least two-thirds of the approximately $50 billion that the Government has allocated to this 30-year-plus program will be spent in the sustainment phase

"This is the period after the initial build and involves the operations, maintenance, upgrade and in-service support of the submarine.

"Many Australian businesses have been tracking this opportunity and are well positioned to be involved."

Barracuda to displace 4,500 tonnes of water

The Australian Government stipulated that its next fleet of submarines would be conventionally powered, ruling out larger, nuclear powered submarines of the type the US commandeers.

DCNS said in its pitch that the diesel electric Barracuda would utilise a conventional pump jet propulsion system that would be more quiet than "obsolete propeller technology".

It said a pump jet propulsion "always had a tactical advantage" over an otherwise identical submarine with a propeller and would be fitted with the "most powerful sonar ever produced for a conventional submarine".

It said each submarine would be 97 metres long, weigh more than 4,000 tonnes once submerged, and displace 4,500 tonnes of water when it surfaces.

DCNS also said it would build a "mega submarine" construction facility in Adelaide if it won the bid.

Mr Walters said it was critical that Australian industry became closely involved in the engineering aspects of the Shortfin Barracuda's design.

He said bidders had only been asked to provide a pre-concept design to meet Australian capabilities and did not have a fully designed and developed submarine.

"This then creates an immediate opportunity," Mr Walters said.

"The build of the submarine may be many years away but the opportunities to be involved in the design phase will start now.

"It is critical ... that we now focus on our role in the design of the submarine and the development of the critical skills to sustain the fleet throughout its entire life."