February 18, 2016

Submarine Implications of Woody and the 3 Reef bases

Woody Island (featured in the previous article) is another naval base and stationary "aircraft carrier" for China in the South China Sea. This is in addition to Subi, Mischief and Fiery Cross Reefs (the "3 Reefs") acting as Chinese "carrier" naval/air bases in an even more contested area. See those 3 Reefs on the second map below. 

Woody and the 3 Reefs are in the Paracel and Spratly island groups respectively - all in the South China Sea.

Chinese military aircraft, ships and submarines from China's Hainan Island can extend their range replenishing at the growing air/naval bases on Woody and the 3 Reefs (above and below) or they can be permanently based there.

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Chinese aircraft can use this growing island network to criss-cross the sea in search of Western (including Australian) submarines. See Submarine Matters September 2015 article on the 3 Reefs.

Woody Island defends the approaches to China's much more important Yulin/Sanya naval base (in part a nuclear submarine base) on China's large Hainan Island. Woody also defends other Chinese naval bases and trade routes. Woody is well placed for launching strike aircraft and land attack missiles against air/naval bases on Vietnam's coast.

It is likely that China's active SSBNs consist of 4 Jin class, Type 094 submarines (4 more being built). Unlike the US, UK and France, which have a technological and development time lead in quiet SSBNs, Chinese SSBNs are believed to be significantly noisier. This means China relies on creating a safe bastion to defend its growing SSBN, SSN and SSK forces. Without this "bastion" China's SSBNs cannot amount to a credible second strike capability because they would be destroyed too quickly (particularly by the US SSNs operating out of Guam).

A principal role of China's SSNs and SSKs is defending its SSBNs from Western (US) SSNs and (Japanese, Australian, South Korean and perhaps Singaporean) SSKs.

The bastion defences are in the form of:

-  long range DF-21D anti-shipping/anti-submarine missiles based on the Chinese mainland and maybe Hainan.

-  Hainan, Woody and 3 Reefs based MPAs, helicopters and ASW warships

-  Large Chinese ASW UAVs (eg. "Divine Eagles") are also being developed which will be launched from the island/reefs.

-  For ASW and anti-shipping China can also string its undersea SeaWeb (SOSUS just part of it) networks between the island/reefs and the Chinese mainland. These networks can be laced with seabed or tethered mines, which can be remote-armed against Western shipping and subs during times of crisis.

China's conventional diesel-electric submarines (SSKs) only have limited range and endurance. Woody Island and the 3 Reefs provide much needed friendly-to-China bases where the SSKs can refuel and replenish other supplies (including specialised AIP chemicals for the Yuan class SSKs).

China's increasing militarisation of the Paracels (including Woody) means that Australia needs submarines of increasingly longer range. Australia's future subs need to be able to operate from Fleet Base West (south of Perth) - quickly transit to-from (more than 6,000 kms total) and actually remain on station for around 4 weeks unrefueled.

Chinese satellites and long loitering UAVs will soon mean that Australian submarines cannot transit/operate surfaced at any stage. Operating the diesels while running across Chinese SeaWeb networks will also become dangerous. Lithium-ion batteries and AIP may become essential - on the way to nuclear propulsion (within the next 25 years).



Anonymous said...

I support your conclusions that a future Australian submarine needs to have both LIB and AIP. I agree with you that given the potential threat, all submarine operations within the small SCS needs to be at silent speeds as much as possible. This is true even for Vietnam although they operate the Kilo 636.1 as there are differences with the Chinese 636 and 877.
On the subject of SOSUS or microphones, for the temperature and salinity in the SCS, they will be best at ~1km depth where there is nearly no attenuation of certain frequencies. Now when you look at the SCS sea bed topography, China could lay a SOSUS east of Hainan to HongKong to monitor the Luzon strait. East of the Paracel group, South of Hainan and at the mouth of the gulf of Tonkin, they can lay another network, but East of the Paracels, the depth is much deeper than 1km. The same goes for the Spratly islands. Recall a few years ago where there was an incident between China and the USN when a US oceanographic vessel was operating east of Hainan near the undersea wall there.
However, for Vietnam, a SOSUS type of network can be laid at ideal depth all the way from Danang down to to Vung Tau along its central coast since the sea Microphones operate best when there is a huge wall behind them to capture sounds. This can monitor the entire midle portion of the SCS between Vietnam and the Philippines, including the Spratly islands. Last year a Chinese cable laying ship was followed closely by the Vietnamese navy when it passed through Vietnam territorial waters. It may be legally debatable if you can lay a cable within an EEZ but it is clearly illegal to do so in someone else's territorial water.
The same can also be said about the Philippines coast line where there is a deepening undersea wall within its territorial waters down to Palawan. SOSUS technology may be beyond the capabilities of both Vietnam and the Philippines but this is a potential win win partnership with external suppliers.
Note that with a SOSUS type of network you do need a head end station not so far away since you are dealing with very small noises which can be masked by cable and amplifier noises if they get too long.

Anonymous said...

FYI: http://news.usni.org/2016/02/15/china-reclaimed-land-for-south-china-sea-anti-submarine-helicopter-base-near-vietnam.

Duncan island is in the Crescent group within the Paracel archipelago. The naval battle of 1974 happened here. An ASW station is clearly aimed at monitoring Vietnam's Kilo if they go to Danang or to the Gulf of Tonkin. The undersea wall is quite a way west of Duncan. Inside the Gulf of Tonkin, the sea is too shallow to make hydrophones effective.

Duncan island is also 300km from Vietnam and Sanya and that is also the range of the 3M-14E Klub.

Josh said...

I would suspect that these island bases are sufficiently close to the mainland that I doubt they will receive a lot of traffic from MPAs, HALE UAVs, or submarines or other long range platforms. For the most part these systems have sufficiently long range that basing the infrastructure for supporting them on these tiny facilities isn't especially cost effective. I suspect tactical fighters, ASW helicopters, and MALE UAVs will (or have) been based there and that they will function as emergency/divert fields for other larger platforms. Their most expedient use likely will be as forward radar stations (not exclusively or necessarily SAMs), communications links, and eventually AShM launch positions. They are rather indefensible in any serious conflict but staffing them with such equipment is a low cost effort that gives a persistent presence, ISR, and C3 capability in peacetime while cementing the political goal of claiming the South China Sea.


Anonymous said...


An MSDF team was dispatched to Danang, central Vietnam, along with two P-3C patrol aircraft for the drills aimed at reinforcing defence cooperation between the two countries and keeping a check on China amid territorial disputes in the South China Sea.


Peter Coates said...

Hi Josh [at 19/2/16 12:12 AM]

Of course the islands/reefs would be vulnerable in medium-high level warfare and correct they are not all 1,000s of km away from mainland China. Though the 3 Reefs are a distance.

But being defensible property of China (in peacetime and low level warfare) is much of their value.

Through militarising (working on) the islands China is holding ground and staking claim to the surrounding ocean, air and undersea assets.

At the moment fishing pays a bit. Oil/gas is a future possibility once world prices go up. Strategic position is the main game - I think.

In terms of strategic: shuttling MPAs, fighter-bombers, warships and SSKs gives China the second most powerful hold on the South China Sea after the US.

I need to reiteratte that China has built full length runways on the 3 Reefs, not just Woody.

For UAVs the ability to land on reefs, like Mischief, gives UAVs much more loiter time and closer being to the action when needed.



Peter Coates said...


[at 18/2/16 10:41 PM] thanks for the calculations and analysis on subs and especially SOSUS.

Some addittional points:
- Partial tethering and use of buoys can extend the network across the deep troughs.
- As well as permanent seabed SOSUS the US, and I would say soon China, can drop sensor networks from ships, subs and aircraft in tense times before a possible conflict.
- Senser networks need not be wire connected but can send radio signals to satellites for rely to land-stations.
- once a SOSUS (SeaWeb) line/array is "tripped" Chinese cruise missiles or DF-21D can be launched against the Western ship or sub that is doing the tripping.

Yes SOSUS laying is expensive - probably mainly done by Russia, China, US and Japan.

Thanks for your [18/2/16 10:56 PM]FYI: http://news.usni.org/2016/02/15/china-reclaimed-land-for-south-china-sea-anti-submarine-helicopter-base-near-vietnam. ]



Peter Coates said...


Exra thought on SeaWeb under sea sensors.

Where seas are shallow/littorals diminishing or precluding sonic/SOSUS I look at other SeaWeb undersea sensors that may be colocated eg:

- photoelectric
- infrared
- smart-movement sensors
- magnetic and gravity anomally
- hypersensitive radiation.

All these can cue satellites and UAVs to take a more thorough view from the top. Snorting SSKs showing snorkels and wakes know they are vulnerable.

There is so much that Australia needs to overtly study about its near north, South China Sea, area.



Anonymous said...

A Russian documentary on Project 636 including its building.

When I look at China attempting to reinforce its claims in the SCS and East Sea, I do see some analogies with the US (then an emerging power) challenges to France and England, the premier naval powers of the time, at the end of the the 18th century with the Quasi wars and a few years later with the War of 1812. The circumstances leading to those wars are very different of course. Instead of the SCS we have the Caribbean Sea, instead of Chinese patrols in the Gulf of Aden, we have the US two Barbary Wars with the Ottoman Empire and North African states.


Peter Coates said...

Hi KQN [at 22/2/16 10:02 AM]

Thanks foor the 636 doco. Here's interesting youtube on the Kilo https://youtu.be/mh3Z6K7ogqo just over 2 minutes.

Yes the US certainly caught up with the imperial powers through pursuing its self-described "manifest destiny" https://en.wikipedia.org/wiki/Manifest_destiny#Beyond_North_America - especially during the 1898 Spanish-American War. The US ejected Spanish colonialists from Cuba, Puerto Rico, other Caribeans areas and the Philippines.

The US also reminded European powers that the "Western Hemisphere" (Americas) was the US's sphere of influence (the Monroe Doctine).

But the US only faced weak or non-existent incumbents while China is working with a SCS that is highly contested.