This has taken me a couple of days to get to, but Hans Kristensen penned a nice post (China’s Noisy Nuclear Submarines) about China’s new Type 094 ballistic missile submarine, based on an Office of Naval Intelligence document entitled The People’s Liberation Army (PLA) Navy: A Modern Navy with Chinese Characteristics.

Three things stand out:

1. China now has three ballistic missile submarines, one Xia class and two Jin class.

2. One Jin class submarine is based at Hainan. The other Jin and the Xia are at Qingdao.

3. The Jin is really frickin’ noisy.

The last point is something we suspected, but it is nice to see in black and white — or, in this case, in full color.

How Loud is China’s New Boomer?

The most interesting informtion in the ONI slickee is a nice chart showing the relatively loudness of Chinese and Russian nuclear submarines.

Which is more or less what we thought when we did an estimate in July 2007. (See How Capable is the 094?) This is actually the second chart that ONI has released showing the relative detectability of Chinese and Russian nuclear submarines. The first chart, released in 1996, was a nice x-y plot showing radiated noise by deployment year:

Source: Worldwide Submarine Challenges 1996, Office of Naval Intelligence. Note: The “1997 edition” is online but doesn’t seem to have this chart; the image is from the 1996 copy. I incorrectly stated it was from the 1997 edition in a previous post.

When one compares the 1996 ONI chart with a similar chart (below) from Tom Stefanick’s Strategic Antisubmarine Warfare and the Naval Strategy, China’s Type 093 or Shang-class SSN seems to clock in at 130-150 decibels (re 1 micropascals at one yard. Since the Jin-class is derived from the Shang, all things being should be a little louder, this worked as a conservative estimate for both.

(In case you like reading the fine print, 1 micropascal is the standard reference pressure for measuring sound in water. Don’t get me started on root mean square.)

Of course, the 1996 ONI chart was before the Shang and Jin class went to sea, so it was a projection. To add to the uncertainty, I was eyeballing the chart, which is not exactly a precise approach.

As it turns out — based on the new ONI chart, which I’ve turned on its edge — I would revised upward the loudness of the Jin class submarine to perhaps 140-160 dB re1 µPa at 1 yard. (I would revise upward even more the Shang, which is surprisingly loud.)

It is difficult to convert this in to an easily understandable measure of detection, but it seems that Chinese ballistic missile submarines lay along the same displacement/noise curve as Soviet-era ballistic missile submarines. (“As submarines grow quieter, they tend to grow in size to acommodate the sound isolating mounts,” wrote Stefanick.) The most obvious comparison for the Jin class SSBNm, in terms of size and noise, is the Soviet Delta 1 — which is not a flattering comparison.

Operational Patterns?

Overall, the Jin is a very impressive submarine — for the 1960s.

Which brings up other questions of what sort operational pattern would you develop to operate a ballistic missile submarine that makes one hell of a racket?

I continue to be skeptical that China will adopt the “continuous at sea deterrent” posture favored by the United States, United Kingdom and France. China could do so, of course, but it would probably require additional submarines and would be a very big organizational change for the Chinese military. (See: Will China’s Deterrent Go To Sea?)

The Western model is not the only one. Russia, for instance, does not routinely patrol its ballistic missile submarines. Here is a chart of Russian SSBN patrols by year released by ONI, and kindly provided by Hans Kristensen:

Russian SSBN Patrols by Year

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
11 7 6 1 0 2 2 3 5 3 10

It is worth noting, furthermore, that in 2006, the patrols clustered, meaning that even in high years, deterrent patrols may not be continuous.

Of course, Russian SSBNs sitting pier-side are within range of US targets, while Chinese SSBNs are not. (Moreover, the Russians seemed to have developed the ability to launch from pier-side, which may not be a capability that interests the geographically-distant Chinese.)

So what kind of operational pattern might China adopt for its boomers? This is pure speculation, but I continue to think that the Chinese might choose to keep their submarines largely in port other than for training missions and “flush” them to sea in crisis to demonstrate “resolve.”

No, I don’t think that is a good idea. But Chinese officials think about deterrence primarily as having capabilities and, in a crisis, of signaling resolve. Moreover, Chinese boomers probably maximize survivability when they head out to sea with many other submarines to occupy the US Navy.

I don’t blame analysts for trying to make informed guesses about what the Chinese are going to do — it is really anybody’s guess. The Chinese themselves may not know. (Or, to put it another way, certain groups may have preferences but don’t know whether they will get their way.)

We will see soon enough.

One data point to track is the force size: ONI predicted five submarines on the assumption of “continuous at sea deterrence.” (Chinese Military Power continues to hedge it bets with “up to” five.) In 1999, DIA predicted just three by 2020 – a refitted Xia and two Jin. More than two years after spotting a pair of Jin class submarines side-by-side, that is where the China’s SSBN force happens to be.

Does this mean the decade-old DIA projection was correct? Or is it just a coincidence, like a stopped watch being right twice, while the Chinese outfit more hulls as predicted by ONI? It is impossible to tell from the open source information.