September 26, 2017

India May Want to Buy Japanese Submarines

Might Japan one day sell India a for export specification submarine similar to Japan's Yushio-class design - with pressure hull steel equivalent to High Yield HY120 and air independent propulsion (AIP)? (Photo via Wikipedia).

Japanese Prime Minister Abe's Indian visit in mid September 2017 raised the issue of a possible future sale of Japanese submarines to India. The sale would be under Project-75(I) to supply the Indian Navy with 6 AIP submarines. The re-issued and extended RFI might be steadily giving Japan a better chance of winning. Japanese Soryu submarines have been mentioned, but they may be too highly classified and expensive. Hence a for export specification Japanese design might be more likely.

Ever since Pakistan introduced MESMA AIP into its latest 3 Agosta submarines India has been intent on also acquiring AIP for its own submarines. China also has (Stirling) AIP (locally developed or bought from Sweden) in its Yuan submarines.

India's Defence Research and Development Organisation (DRDO) has long been developing a fuel cell AIP technology, but this is a very difficult - so much so that Germany is the only demonstrably successful fuel cell AIP developer.

Recent border friction with China and increased Chinese submarine activity in the Indian Ocean has underlined to India that it needs more powerful conventional submarines quickly. India's perpetually delayed Project 75(I) AIP submarine selection project is therefore being accelerated.

Chances that Japan is now a serious contender in Project-75(I) may be increasing. Japan builds highly capable large submarines (which can carry more missiles, torpedoes and mines) and has long experience with Stirling AIP (probably bought from Sweden). Japanese sale of Stirling AIP to India would likely require involvement of Sweden. Stirling AIP is likely superior in quietness and low heat signature to MESMA AIP. A submarine purchase from Japan would also boost a key regional strategic friendship against India's and Japan's strategic competitor, China.

Regional friendship is something Project-75(I) competitors (Germany, France, Sweden) in distant Western Europe, cannot deliver. Northeast Asian nations, (Siberian) Russia and South Korea, also competing for Project-75(I) are both careful not to antagonise China.

Japan's large 2,900 ton (surfaced) Soryu submarines might be uncompetitive as they may be priced at US$1.5 billion each. This is in comparison to US$1 billion for 1,800 ton 75(I) competitors.

Japan does not want its most tightly held submarine secrets finding their way to China - so Soryu technology may be too sensitive. Japan would be wary of India's exchange of submarine high technology with Russia in the form of Kilos, naval reactors and SSNs. Russia also shares submarine technology with China.

Due to these security concerns Japan is unlikely to offer its Top Secret high yield pressure hull steel. That steel is Japanese NS110 grade - equivalent to US High Yield HY156 used in the Oyashio and Soryu classes.

Instead Japan might supply lower specification for export submarine technology - particularly pressure hull steel used in Japan's older Yushio-class design ie. Japanese NS80 grade (equivalent to still advanced US High Yield HY120 steel - see the Table on Submarine Matters).

When eventually decided India's Project-75(I) competition will be a major win for any of the competitors.



Tri-ring said...

To my knowledge the Stirling engine JMSDF utilizes is under license so Japan can't offer it without the owner's consent.
As for the class, I believe IF Japan accepts it will provide the Soryu class desig with some modifications. One will be VLS which I believe India will want and also a air lock for special forces to move out. JMSDF would most likely wants this to enlarge the scope of operation for the subs as well and make it a co-development project if India agrees.
I concur that ATLA would only offer the NS 80 and not the top grade NS 110 steel as well.

PUNTER said...

NS 80 pressure hull with Solid State Battery without AIP may be good for India. AIP may be obsolete in the near future.

GhalibKabir said...

I am quite skeptical of Japanese subs being sold to India (selling is tough enough, local manufacture is a step too far). The US-2 saga is illustrative of the difficulties the Japanese have had with India. At the end Modi had to negotiate what was effectively a 'make in Japan and export to India' G2G deal.

There are other reasons as well. Indian labs like the NMRL, DRDO etc have deemed Stirling AIPs to be noisier than fuel cells (ditto why rejected the MESMA too). (shame is Stirling AIPs on a bunch of Kilos would have given IN exposure to Stirling AIPs like the ones in the PLAN Yuan class SSK)

With this opinion on Stirling AIPs and all the customization requirements reg. VLS, spl forces hatch etc.., the costs will simply be too high and the Japanese will likely (and to an extent justifiably) act as if they are undergoing a root canal without anesthesia on ToT and the other commitments Indian bureaucrats might seek...

the Indian version of the MHI/KHI 'Soryu' will be one white baby elephant no body would want to hold. We can carve it into granite this deal ain't happening.

I would rather say take the help of TKMS on a G2G basis and start two parallel lines making a PEMFC AIP Type 214 ocean going version in both Germany and in India. This is about the only thing that is going to realistically work for the 75I. Along the way may be India can test its own PAFC AIP on one of the Type 214s or later Scorpenes.

PS: The Indian bureaucrat's ability to make a dog's dinner out of anything is the stuff of legends by now.

The Indian Bureaucrat, Delhi's Fright and Beijing's Delight!

GhalibKabir said...

to add, India is already making the DMR 292A steel (equivalent to the Russian AB-3). So the NS-110 might be not so big a factor after all in considering JP help.

Some of the knowledge from working on the Arihant class (I know Russia gave NS-80 grade steel for the lead boat) and Scorpenes should help with making more and more steel for later line submarines both N and D/E...

that does not change the conclusion I am inclined to soryus for IN

Peter Coates said...

Hi GhalibKabir [at 3/10/17 7:08 PM]

Yes the Indian military beaucracy's approach of worrying defence deals to distraction is not what Japan’s methodical contractual approach might tolerate.

Agree that if Japan is rejecting the efficiency levels of Stirling and MESMA then India is unlikely to embrace these types of AIP.

That said, TKMS may not want to share even its 15 year old polymer electrolyte membrane (PEM) fuel cell (PEMFC) technology with India. A concern being India will share PEMFC with Russia and Russia to China. TKMS made a sharing deal with South Korea but India may not come up with the money TKMS expects.

Naval Group’s AIP FC2G (Air Independent Propulsion Fuel Cell Second Generation) [1] late model Scorpene and a few Barracuda/K15 tips may interest India

[1] see



Peter Coates said...

Hi again GhalibKabir [at 5/10/17 12:41 PM]

Interesting India is already making the DMR 292A steel (equivalent to the Russian AB-3). supports your info, with "SAIL’s flagship plants at Bhilai, Rourkela, Bokaro and Durgapur have produced three special steels...SAIL is now developing DMR 292A, special steel for the hull of Indian submarines."

Japan swears by its NS-110. Maybe NS-110 is beneficial in other ways. Say, lower level of magnetic iron in the alloy?

Yes, its likely “no soryus for IN”. Japan really needs to design a smaller 2,500 ton submarine for export.



GhalibKabir said...

PEMFC technology won't get shared. That is a given. Money is one thing, however like the DCNS leaks showed, some times even coughing up exorbitant money is not enough for ToT.
(as much one might dislike, there is a hierarchy not unlike a 'defense caste system')

India either succeeds with its PAFC AIP or goes for

Nuclear AIP using a vSMR or very small modular reactor capable of delivering 0.5 MWe.

PS: India sharing with Russia is over-hyped IMHO. It used to be so till recently..not any more and China has filched enough from the west to need Russian help (may be a bit needed)

PPS: I assume the NS-110 is likely to have low magnetic properties helpful against Chinese and Pakistani MAD booms (on the P-3Cs) etc...however it is still a no go.

Peter Coates said...

Hi GhalibKabir [at 6/10/17 12:08 PM]

Thanks. Re PAFC AIP - here's a useful description


Peter Coates said...

A highly significant Indian media report of part explaining Project-75(I)'s relaxed pace is The Hindu, Business Line's report by Amrita Nair-Ghaswalla, of February 5, 2018 which says in part:

"Indigenous submarine project still a non-starter"

"Acceptance of necessity (AoN) date lapses today

Eighteen months after an extension was granted by the Defence Acquisition Council for Project P-75 (I), which involves the construction of six diesel-electric submarines at a cost of $10.9 billion, neither an Indian shipyard nor any foreign original equipment manufacturer (OEM) has been selected “to get cracking on the project.”

Six submarines planned to be constructed as part of Project P-75 (I) have a deadline coming up. The diesel-electric submarine project has an acceptance of necessity (AoN) date that is set to expire on Tuesday [6 February 2018].

Labyrinthine process

“All defence procurement proposals go through a labyrinthine procurement procedure,” said a senior official at an Indian defence shipyard seeking anonymity. “The first is the AoN stage and then the tendering stage. The first approval for P-75 (I) came in 1999. The delay is hurting everybody,” said the official.

Noting that the project was slated to be the first one to be undertaken under the strategic partnership model, the official said, “Now the AoN extension is set to expire on February 6, without a single shipyard or a foreign collaborator getting selected.”

...Undue delay

However, the delays have been taxing both Indian shipyards as well as foreign collaborators. “We are waiting for the government’s nod to launch the process to select the Indian shipyard for joint manufacture of the submarines with the chosen foreign entity,” an official said.

Noting that it would take another seven years, after all the contracts have been inked, for the first submarine to roll out, the official maintained that another extension of the AoN, “which is a given, would just be an exercise in futility unless the government decides to move ahead and announce the shipyard and its foreign partner.”


I always thought the I in P-75(I) was I for India, but apparently it is for "Indigenous". But India, in this project, is relying on foreign designed submarine types.

Maybe only the AIP and the torpedos will be of Indian design. But AIP and new Torpedos may take 10 years to be developed and 5 years to be retrofitted into P-75(I) submarines.