Defence and French shipbuilder Naval Group have finalised the intended length, diameter and displacement of Australia’s future submarines.

Finalising key submarine dimensions enables the design process to proceed, though right now those key dimensions remain secret.

Naval Group, formerly DCNS, offered a conventionally-powered variant of its Suffren class nuclear attack submarine – called the Shortfin Barracuda – as winning contender for Australia’s new submarine.

That was to be a boat around 90-metres and 4,000 tonnes displacement, with Suffren’s advanced pump-jet propulsion and conventional diesel-electric engines and lead-acid batteries.

Jean-Michel Billig, Naval Group’s executive director for the Future Submarine program, said Suffren was only the starting point for Australia’s submarine requirements.

“We don’t consider it difficult because we are not converting a nuclear-powered submarine into a conventional submarine,” he said.

“We are starting from scratch, the benefit of our expertise in designing submarines whether they are nuclear or conventional because we have been also designing conventional submarines such as Scorpene. We are starting from scratch to make sure we address very accurately the operational requirements from Australia.”

Billig said the choice of technology for the Future Submarine was being driven by those requirements.

“Where Australia is particularly demanding is about the acoustic performance of the submarine. The acoustic performance of the submarine will be driving the technology we will select for the propulsion system.”

Billig said the design would most likely include air independent propulsion for maximum endurance.

However, he stressed that it was too early to elaborate on selected technology.

“Through the feasibility phase, we need to fine tune the design against each individual requirement. Only at the end of the feasibility phase will we be able to tell you this is the technology we have as it is best answering the requirements. At this point in time it is architecture only.”

Billig said Naval Group and Italian shipbuilder Fincantieri were now discussing a potential joint venture approach to maximise their potential to sell ships in the Asia Pacific region.

He said the two companies had worked together previously, including on the European multi-mission frigate (FREMM), one of the three contenders for Australia’s Future Frigates.

“We know each other. It is meaningful to think about, not a merger but a kind of joint venture, yet to be defined, what could be done in common,” Billig said.

“The purpose of the working group … is to provide some conclusions by mid next year to say what could be meaningful to put together as assets from Fincantieri and Naval Group for the benefit of those companies who would keep their own autonomy in business development.”

Billig said about 15 years ago the centre of gravity for naval industry was in Europe but competitors had since emerged in Korea, China and other countries.

He said it was time for Europe to make best use of its strengths.

“We believe we are at the forefront of innovation, be it Naval Group or Fincantieri and we believe we need to combine our efforts to make ourselves even more attractive to our customers,” he said.

Billig said this would have no impact on the project to build submarines for Australia.

“We won’t have Fincantieri in any way intervening in this organisation. Naval Group Australia will take full ownership and will get the design authority to build and sustain those 12 submarines.”