SEA 1000: why should we have to choose Option J?
11 Mar 2016|


The current strategic/political argument to buy Japanese submarines doesn’t stand up against a $50+ billion life cycle submarine project for acquisition, sustainment and upgrades which will run until at least until 2060.

Alan Behm’s recent assessment of strategic partnerships makes valuable reading on this subject.

There is no off-the-shelf design that meets Australia’s capability requirements. The engineering and Australian production challenges to be overcome by Japan to scale-up the current Soryu to a suitably evolved platform, are critically important for the CEP to assess.

Recent commentary advocating moving Australia’s naval shipbuilding into the digital age highlights the huge effort already made by German contender tkMS to understand and bring into use a methodology and tools (also now used by three US naval shipyards) to resolve scaling issues ahead of commencing actual construction.

There’s no doubt that the MHI and KHI shipyards in Kobe can build superb submarines which perform reliably and to specification, but they only have a planned 20 year life, not the 30 years Australia wants. And there’s another rub, neither MHI nor KHI have built or sustained a submarine outside Japan, whereas the Germans and French are widely experienced in overseas builds and ongoing support. Perhaps during his visit the MHI CEO should have explained to Australia’s media why Japan declined to bid to construct its own submarines in India for the Indian Navy?

Usable space on board a submarine is determined by surface displacement. The Soryu’s surface displacement is 2,950 tonnes compared with 3,100 tonnes for Australia’s existing Collins Class. Fully submerged displacements are about one third larger, with this increase largely accounted for by fuel tanks and ballast water surrounding the main pressure hull. A fully submerged Soryu is propelling around 1,300+ tonnes of fuel and sea water, for a range which is currently about two-thirds that of Collins. An evolved Soryu will have to be increased significantly in size to accommodate even more fuel and ballast water.

Not only is range an important consideration, but as advised by Peter Briggs so too is the period a submarine can remain deep, or in transit below snorkel depth. Both French and German designs will include the option of proven air-independent propulsion, while Japan is moving away from its Kawasaki Stirling AIP engines for Soryu’s  seven and eight, to seek range at depth by incorporating some lithium ion batteries (LIBs). All three contenders will incorporate significant battery technology improvements, including the use of LIBs because they have a much higher charge density in a smaller form factor than traditional lead acid accumulators.

Increased LIB charge rates and a power hungry US-supplied AN/BYG-1 combat system, never before fitted to Soryu, will dictate a total re-design of its power generation and distribution system. As well 6MW size permanent magnet synchronous electric motors must be developed, larger than any such existing submarine main engine—a risk to be managed for all contenders.

Modern European submarine construction uses a single pressure hull, while the Soryu class uses a combination of double pressure hulls for the forward and aft compartments, but with a different steel alloy from single pressure hulls for the intermediate four compartments. Does this create differential expansion/cracking and corrosion problems at the dissimilar metal junction and is this the reason why Soryu has a 20 year life, not the 30 required by Australia?

While double pressure hulls increase a submarine’s reserve of buoyancy, they also increase cost and complexity of manufacture, probably give a shorter planned sea life, and increase the wetted area of the submarine requiring more energy to propel the vessel underwater.

A 4,200 tonnes Soryu has a crewing capacity around the same as Israeli Navy’s 2,400 tonnes Dolphin 2 Class submarines. The physical layout inside the current Soryu won’t meet ergonomic standards for future RAN submariners, affecting their alertness, health and welfare during a long range/endurance mission. Arguably the current Japanese internal design is inefficient and a poor starting point for an evolved Soryu detailed design.

One of the most telling differences is experience in overseas builds and sustainment. The Germans committed to that from day one and have a wide range of Australian partners and international experience. The French also engaged widely during 2015 and are again in 2016 seeking out further potential Australian sub-contractors. As yet there’s limited evidence of real Japanese effort, despite fine words.

Both French and German contenders have built submarines for their own country’s navies as well as for other navies in their own countries. The Japanese have not, even though in October 2015 Masaki Ishikawa, from Japan’s Ministry of Defence, said the Japanese consortium is ‘very confident that we can build boats from Day One in Australia’. This really is a bridge too far and too important for Australia to risk its key 50 year strategic defence project to the hands of a trusted, yet inexperienced, ally.

Let’s hope our politicians leave Defence’s CEP alone, and allow it to reach the right conclusion mid-year after a balanced consideration of all factors.