February 20, 2015

Possible Japanese Submarine Deployment Area


Differing submarine patrol areas strung along China's First Island Chain. Japan's submarine patrol area may be from Kyushu, along the Ryukyu island chain (which includes Okinawa), south to Taiwan, then across the Bashi Channel (Luzon Strait) down to Luzon Island, Philippines.
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Part of the "First Island Chain" is what Japan calls the Senkaku Islands. A potential China-Japan-(maybe)Taiwan flashpoint due to undersea oil deposits. These deposits may become economically extractable as oil prices rise and technology permits. 
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Below is an interesting snippet which may reflect how Japan's submarine fleet is deployed:

Tetsuo Kotani, U.S.-Japan Allied Maritime Strategy: Balancing the Rise of Maritime China, (Strategic Japan, Japan Chair) Center for Strategic & International Studies (CSIS), Washington DC, April 2014, pp. 1-15. http://csis.org/files/publication/140422_Kotani_USJapanAlliance.pdf wrote on page 12:

"In addition, the submarine fleet will be increased from 16 to 22. Due to the lack of Chinese ASW capabilities, the expansion of the submarine fleet enhances sea-denial capability vis-à-vis the PLAN. To patrol the waters along southwestern Japan, it is estimated that at least eight submarines are necessary (six for the Okinawa island chain [Japan to Taiwan] and two for the Bashi Channel [also called (Luzon StraitTaiwan to Luzon island, Philippines]. Typically, a [submarine] requires two backups for training and maintenance. Thus a submarine fleet of 24 is ideal, but a fleet of 22 provides more operational flexibility than the current fleet of 16. [35] On the other hand, for the effective use of the reinforced submarine fleet, the JMSDF needs to recruit and train more submariners." 

[35] =  [retired Vice Admiral] Masao Kobayashi, “Sensuikan 22 sekitaiseino Kaijoboei” [Maritime Defense under a 22-Submarine Force], Gunji Kenkyu [Japan Military Review], December 2011. http://gunken.jp/blog/archives/2011/11/10_0000.php

COMMENTS

Page 1, 2nd paragraph indicates Japan's submarine deployments may, in part, respond to "Beijing’s attempts to deny access by other maritime powers to its Near Seas (the Yellow Sea and the East and South China Seas), which are enclosed by the first island chain (a chain of islands from Kyushu, Okinawa, to Taiwan and Borneo)." 

Japanese strategy using all forces, including submarines, is partly to provide a blockading force (in time of conflict) to keep China forces and trade bottled up in China's near seas. Japan, its SSK owning allies, and the US SSN force could also block Chinese naval vessels and supplies (such as oil) from reaching China. 

As the CSIS excerpt above indicates Japan's main submarine patrol area would be from the the southern home island of Kyushu, along the Ryukyu island chain (which includes Okinawa), south to Taiwan, then across the Bashi Channel (Luzon Strait) down to Luzon Island, Philippines. 

Countries in the region may make frequent use of undersea arrays (along with future use of UUVs (including wavegliders)), particularly in narrow straits and harbour mouths. Such use would diminish reliance on virtually stationary submarines guarding critical straits and harbour mouths. 

South Korea would monitor movements in all the congested seas and straits near South Korea. In those seas are threats or possible competitors North Korea, China, Russia and Japan itself.

The US with its wide ranging SSNs may guard some straits and narrows but the speed and range of its SSNs allow open ocean (blue water) coverage throughout the Pacific, Indian Oceans and under receding Arctic ice to the Atlantic Ocean. US SSNs can act as backup to the SSK navies (Japan, South Korea, Singapore, Australia) particularly against Russian and Chinese SSNs. All of the allies would directly or indirectly (via the US as the common ally) work together under the blanket term SeaWeb.

Naturally submarines are not the only blockers or monitors and don't work alone. Other platforms (surface warships, surveillance satellites, UAVs, UUVs, patrol aircraft including helicopters, land based missiles and ground stations (deploying radar, intercept and other arrays)) can work with submarines in the whole defence mix

Pete

6 comments:

Anonymous said...

Dear Pete,

according to the statement by Tetsuo Kotani the distance for the Soryus to their operating area is about 1,500 nm or less. Why should the Soryus should have such an excessive range like Collins-class?

The huge torpedo load of the Soryus is to kill tonnage. The German Type XXI had 23 torpedoes. The Type XXIII just 2 tubes without reloads just like Cold War Type 206 submarine had 8 torpedo tubes without reloads. Type XXIII and Type 206 were to attack enemy Navy ships and not freighters or oil tankers. Germany got 18 Typ 206 and thereofore about 6 submarines with 56 torpedoes ready to counter an attack. They would have been lucky to fire 8 shoots and more lucky to get out.

Regards,
MHalblaub

Peter Coates said...

Hi MHalblaub

That operating range difference 1,500 nm for Japanese Soryus and maybe 5,000 nm for Australian Soryus is (or will be) a big issue.

It could that Japan may lengthen its operating range to be capable of intercepting Chinese subs and oil tankers all the way into the Indonesian Archipelago (especially Strait of Malacca).

Japan's decision to not include Stirling AIP for the new Soryus suggests a major revision in Japanese mission priorities.

Or it could be that Japan will stay with 1,500 nm and build a highly modified long range Soryu for Australia.

I think Australia would be prepared to trade 10 of the Soryu's 30 torpedos for an extra fuel-oil tank.

Regards

Pete

Anonymous said...

Soryu loads total of 30 Type 89 torpedos and UGM-84 Harpoons according to Wikipedia, but I believe it’s 20 not 30 according Japanese source. And actually, they don’t use Harpoons, because enemy can easily detect location of submarine after Harpoon launching. Armamnet of Soryu is not powerful.

Anonymous said...

Dear Pete,

that Japan will not use Sterling AIP on their next submarines does not exclude an AIP.

Japan is not so narrow minded to not switch to a better solution.

Maybe they choose an already working fuel cell solution...

Regards,
MHalblaub

Peter Coates said...

Hi Anonymous of (March 1)

You might be right that the Soryu can only carry 20 reloads.

Wikipedia http://en.wikipedia.org/wiki/S%C5%8Dry%C5%AB-class_submarine says:

"30 reloads for:
1.) Type 89 torpedoes
2.) UGM-84 Harpoon
Mines"

Unlike torpedos and Harpoons which are full reloads 2 mines can fit into a torpedo tube reload.

Therefore "30 reloads" may more accurately mean 30 weapons - which includes 20 mines, hence:

10 x torpedos or Harpoons and 20 x mines.

So your statement that the Soryu carries only 20 reloads (within that 30 weapons) may well be correct.

Regards

Pete

Peter Coates said...

Hi MHalblaub

You may well be right. Japan is advanced enough in submarine building to develop its own fuel cell AIP or include German fuel cell AIP under licence.

Perhaps only Japanese built future submarines earmarked for Japan may include AIP. Australia chose more diesel for longer range, instead of AIP in the Collins. That no-AIP preference is likely to continue for Australia's future submarine.

As AIP is a selling point for TKMS-HDW submarines Australia not wanting AIP may play against selection of TKMS-HDW.

Regards

Pete