June 14, 2017

Japanese Submarine Developments Continue

The following are mainly from comments made May 26 to June 6, 2017 on hull research, new diesels, and Lithium-ion Batteries (LIBs):

Research on Alfa STYLE hull shape

The Japanese Ministry of Defense’s (MoD’s) ATLA research organisation is studying a significantly different prototype submarine shape (see last line in this MoD (in Japanese) document). The shape is similar to the old Soviet Alfa-class which had a streamlined fin/sail. Shape differs in having modern X-plane rudders. It was exhibited at the ATLA Technical Symposium 2016. 

It could be the Japanese are talking to TKMS which also features a highly streamlined fin/sail in the Type 212A (photo of model below). These fin/sail styles can provide improved hydrodynamic motion efficiency, noise reduction against passive sonar and the rounded shape may be  more stealthy against active sonar. 

New Diesels for the First of a New, Post Soryu, Submarine Class

29SS will be the first submarine of a new Japanese class (see this Table). It will probably be named after a famous ship in Japanese naval history. 29SS will charge Lithium-ion Batteries (LIBs) only and will likely be contructed at the MHI shipyard, Kobe with launch in 2023. It will be equipped with 2  advanced, more powerful, diesel engines and a high pressure air tank [for what?]. The diesel engines' possible modifications to increase power may be increased bore, stroke and/or charging pressure, and reduction in vibration/noise, etc.

The current Soryu diesel is KAWASAKI-12V/25/25SB
It is a V12, with bore 250mm, stroke 250mm, volume 147L, piston speed 10m/s, power 2280 kilowatts/minute [?] kWm, power/volume 15.4kW/L. This is considered adequate for the Lead-acid Battery (LAB) Soryu Mark 1.

The future diesels need to be more powerful to take advantage of the quick battery charging ability of LIBs. More powerful diesels might include:

-  Kawasaki-12PA6V-280CL V12, bore 280mm, stroke 350mm, volume 258L, piston
   speed 8.4m/s, power 3540kWm, power/volume 13.6kW/L or

-  Wärtsilä 26, 12V26 V12, bore 260mm, stroke 320mm, volume 204L, piston speed 10.7m/s, power 
   4080kWm, power/volume 20.0kW/L or

-  a Kawasaki modified MTU 4000?

Japan Choosing NCA formula LIBs?

On February 17, 2017 Submarine Matters reported on the two types of LIB (“NCA” and “LTO”) that Japan is considering for its new submarines. It may be likely that Japan prefers NCA (Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2)) produced by GS Yuasa (GSY). GSY’s cells have coatings that reduce the fire risk.

Note the Soviet Alfa class 1971-1990 (above) had a highly streamlined fin-sail (Photo courtesy findmodelkit). The fin/sail of the TKMS Type 212A (below) (Photo courtesy HobbyBoss) seems to owe much to the Alfa. Japan, when considering future hull shapes, might seek TKMS' advice on the fin-sail.

Future Submarine Matters articles this week will be:

-  June 15, 2017 on Robust Submarine Diesel Engines: Some Important Considerations from
    comment on 10/6/17 10:16 AM and

-  June 20, 2017 carrying comments on Japan's future 29SS submarine and LIBs (GS Yuasa) etc.



Anonymous said...


Its not clear to me what that level of streamlining would do for a D/E submarine. For a 40knt+ nuke boat it makes sense; for a 20knt D/E on its best day I don't understand the desire to drastically change the hull shape. It might be a little more efficient, but at the 5 knt patrol speed and 10 knt rate of advance (*best* case) does streamlining matter at all? Thoughts?


Anonymous said...

Hi Pete

Outline of research on submarine shape for fluid noise reduction and trial production by ATLA is as follows.

1 Comcept
The noise emitted from the submarine is reduced every year.The noise reduction by modification of unit alone such propulsion or rudder has reached the limit. To ensure underwater superiority to the targeted threat in 2030s, research on submarine shape for a fluid noise (= noise caused bythe flow around the hull) reductions conducted, provideing extreme noise reduction.

2 Implementation
Reduction of low frequency noise components accompanyed with interference between the flow around the hull and the propulsion is conducted, and to compatible said noise reduction with current propulsion performance, opimisation of submarine shape is conducted is conducted.
Design, manufacture and test of prototype are condcted to confirm specific functions and performances and to verify the technology.

3 Schedule: i) reseaech/trial production, ii) 2017- 2020; testing: 2019-2022

4Ttotal budget: 1.2 B YEN (140 M AUD)

As shown in 2, improvement of maximum speed is not expected in this R&D. As energy increases according to the cube of speed at high speed regime, achieving maximum speed of 36knot/h needs propulsion power of 50MW in Soryu (currently 6MW). It is difficult. Result of research may be adopted next-next submarine (post-29SS).


Peter Coates said...

Hi Josh and Anonymous

As my text and bringing in the 212A suggest I don't think Japan would radically change hull shape to the extent of the 40 knot Alfas.

- or even to the extent of the built for speed 33 knot (submerged) Albacore https://en.wikipedia.org/wiki/USS_Albacore_(AGSS-569)

As Anonymous suggests I think noise reduction may be the main Japanese alter hull intention (more likely via a more rounded and less prominent fin/sale).

I also think it likely that such a fin/sale might permit more hydrodynamic efficiency moving at current cruising speeds through the water. This might also be expressed as increasing range (for the same diesel fuel amount) from the present 6,000nm to maybe 7,000nm (?) while still cruising at around 5 knots.



Anonymous said...

Hard to believe that with today's radar and AIS, a 7000 ton destroyer can still collide with a 29000 ton container ship. The Burke should have given way and pass to the stern of the cargo ship. Not the USB best demonstration of seamanship. If we cannot even see a massive very noisy ship, silent submarines need not fear.

Peter Coates said...


I'm moving your comment to the new, relevant SubMat article on the Fitzgerald collision which is now at



Anonymous said...

Hi Pete

On July 17, the governments of Japan and Germany have signed a defense cooperation pact that could set the stage for new arms transfers between the two nations [1].

If submarine technology exchange between Japan and Germany is achieved, the two counries can provide the strongest SSK ever.

[1] https://www.defensenews.com/2017/07/24/japan-germany-sign-deal-to-partner-amid-tensions-with-china/
The governments of Japan and Germany have signed a defense cooperation pact that could set the stage for new arms transfers between the two nations.

The agreement, in the making since early 2015, was signed in Berlin on July 17, a spokesman for the German Ministry of

Defense confirmed on Sunday. The deal, inked by the Japanese ambassador in Berlin, Takeshi Yagi, and Katrin Suder, a state secretary and key confidant of German Defense Minister Ursula von der Leyen, was initially reported by Japanese media, which claimed that German officials had objected to any kind of publicity.


Peter Coates said...

Hi Anonymous [at 3/8/17 3:52 AM ]

The July 17, 2017 Japan-Germany Defense Cooperation Pact indeed opens up possibilities for mutual improvements of submarines.

Technology transfer could possibly take the form of:

- TKMS paying high prices for Japanese pressure hull steel formulas, advances snorkel systems, diesel generators and especially LIBs

- Germany could supply 10,000+ nm range improvement technologies, more efficient/smaller crew automation technology, diesel generators and the most advanced AIP technology (Diesel or methanol reformer fuel cell)