[sparky@home]

A US Nuclear submarine USS Connecticut hit an underwater object in the south china sea last Saturday, fortunately, its safe and stable.
An attack submarine primarily designed for hunting enemy subs shouldn't be taken by surprise. Present circumstances in south china sea area are not exactly conducive for surprises, with china flexing its muscles against Taiwan. The question is what could be so big to surprise this large submarine.

https://edition.cnn.com/2021/10/07/p...sea/index.html

Mods: kindly delete if O/T.

[V.Narayan]

The submarine was in all probability cruising close to shore which makes sense if it is monitoring the seas around the various small islands and islets in the South China Sea. The South China Sea also has, I'm told, many uncharted islets and rocks - mariners will know better. Or maybe it bumped into some big object the Chinese left there for surveillance or whatever! Or was it a sunken wreck and the boat was sailing in quiet mode without any sonars being on.

[sandeepmdas]

Originally Posted by sparky@home

The question is what could be so big to surprise this large submarine.

Most probably, a 40-feet container "standing on one end" on the seafloor. The sub was apparently on a "stealth" mission.

Source:
https://www.msn.com/en-in/news/world...edgdhp&pc=U531

[sparky@home]

From the news, it appears the Sub was crusing at a depth, and to have such severe impact, that a couple of crew members were injured, I assume it must be something big. With all the sophisticated equipments they have on board, anything big would have been noticed immediately and to top it they are cruising with the Chinese around the corner, they sure would have been on high alert, so whatever it was, it sure slipped past their hightec equipments. Wonder what it was, whatever it would be, it will probably be a buried secret.

[antz.bin]

I have a question, what happens to the nuclear reactor if a nuclear submarine is sunk underwater by a foreign object and it implodes due to the pressure.

The nuclear energy is no longer being used, the control systems are now underwater and the reactor core may get damaged eventually. The entire ecosystem of the surrounding water could get polluted with nuclear fallout. And since it is water, it can spread to all the oceans through oceanic currents the core is not removed and left there to rot (like most shipwrecks).

Who is responsible for cleaning up such a mess? If say, such a thing would have happened to USS Connecticut in the South China sea, who is responsible to clean it up?

[V.Narayan]

Originally Posted by sparky@home

From the news, it appears the Sub was cruising at a depth, and to have such severe impact, that a couple of crew members were injured, I assume it must be something big. With all the sophisticated equipments they have on board, anything big would have been noticed immediately and to top it they are cruising with the Chinese around the corner, they sure would have been on high alert, so whatever it was, it sure slipped past their hightec equipments. Wonder what it was, whatever it would be, it will probably be a buried secret.

A submarine cruising at depth, say 400 metres, is unlikely to hit an object at unless it is an uncharted stand alone undersea mountain called a seamount rising up from the abyss. A submarine operating in stealth mode would do so with its active sonars - search, navigation etc switched off so as not to give away its presence which is what USS Connecticut was most probably doing. In such a mode the submarine judges its position through inertial navigation and cannot 'see' the outside underwater environment ie it cruises blind. However if the submarine is cruising close to the bottom in a shallow sea {as found over the continental shelf} then it can bump into an object on the sea bed {like a very large rock protrusion or a sunken wreck or hit the seabed itself because of a strong down current or hit the point where the continental shelf starts from the deep abyss. These occurrences, however, have been dramatically rare. Last was USS San Francisco colliding, in 2005, with an undersea seamount while cruising a high speeds at depth. In 2015 HMS Talent, a British nuclear powered submarine, collided with the underwater part of a large iceberg. Not including here submarine to ship collisions which by definition occur at or near the surface.

Originally Posted by antz.bin

I have a question, what happens to the nuclear reactor if a nuclear submarine is sunk underwater by a foreign object and it implodes due to the pressure. The nuclear energy is no longer being used, the control systems are now underwater and the reactor core may get damaged eventually. The entire ecosystem of the surrounding water could get polluted with nuclear fallout. And since it is water, it can spread to all the oceans through oceanic currents the core is not removed and left there to rot (like most shipwrecks).
Who is responsible for cleaning up such a mess? If say, such a thing would have happened to USS Connecticut in the South China sea, who is responsible to clean it up?

If the submarine sinks very deep the reactor will get crushed and contamination will spread. This has happened with ex-USSR submarines. Though strangely the Americans claim there has been no contamination from the wrecks of USS Scorpian {1968} and USS Thresher {1963} both of which sunk in very deep waters!!! If it sinks in shallower waters with a silty bottom the reactors will not implode. The submarine and the reactor will over time get buried into the silty seabed. Then as and when the leaks start in decades or longer it will to an extent be suppressed by the seabed that forms over the submarine. The Russians have recently started the long process of lifting the sunken nuclear boats off the seabed and getting the reactors onshore for proper dismantling and safeguarding. The first of six has been done. Of course this cannot be done if the boat is too deep down.


Photo right below of a ex-Soviet boat recovered from deep arctic waters being ship-lifted back to Russia for dismantling of the nuclear core. One of the six deep water sinkings being planned for recovery.

Photo two below of Soviet November class nuclear boat being towed away after having been lifted from the seabed. {this is from an earlier operation and not from the six deepwater sinkings currently being worked upon}

[GTO]

Mod Note: Thread moved to the CV section!

[srini1785]

I have nothing to add to this discussion but only that this subject reminded me of this :

US NAVY Vs SPANISH LIGHTHOUSE

https://www.youtube.com/watch?v=xkx0MxK-Yl4

[BharathXUV700]

A submarine navigates primarily using sonar. There are two kinds of sonar – Active sonar and Passive sonar. Active sonar is the one where the submarine will emit a signal which bounces off objects and which is more accurate. A passive sonar works on the principle of just listening to sounds bouncing off objects. Key difference is the submarine does not emit any signal. Using passive sonar, in a simplistic manner, would be like us standing in a dark room filled with people and trying to move around based on noises/conversation others are having. If the other people are talking, we can identify them and not get too close to them. However, if they are all silent, you are essentially blind. Of course, this is just a crude and simplistic way of putting it, but the basic principle is correct.
Also, submarines for most of their life spend time identifying and recording various sounds and they make a sonar map or chart which helps them if they encounter similar objects later on. The sea floor is ever changing (natural and manmade causes). A submarine on stealth mode not using active sonar can come across an obstacle which they have never encountered before, and which emits no noise. The true reason of course will most likely never be revealed to the larger world.

[dust-n-bones]

South China Sea is one of the busiest sea lanes in the world. I find it incredible that navies that use these sea-lanes do not have detailed underwater topographies with them, that subs can use 'offline'.

Remember the MH-370 disappearance? To trawl the Indian Ocean for the missing aircraft, research teams created detailed under-sea maps in one of the remotest parts of the planet. Some fascinating detail is here.

[Herschey]

Came across a very interesting conversation on this topic available over Youtube.

https://youtu.be/NBYlOmh4_7w?t=359

[Porcupine]

Originally Posted by dust-n-bones

South China Sea is one of the busiest sea lanes in the world. I find it incredible that navies that use these sea-lanes do not have detailed underwater topographies with them, that subs can use 'offline'.

Remember the MH-370 disappearance? To trawl the Indian Ocean for the missing aircraft, research teams created detailed under-sea maps in one of the remotest parts of the planet.

Mapping the underwater topographies is an incredibly difficult job when you get a perspective of how vast the oceans actually are, even if it's the busiest route.

And in this instance, assuming it hit an object that wasn't a part of the earth, i.e. a moving unknown object - that task is near impossible. It's not just like locating a needle in a haystack. It's like locating a needle that's constantly moving with no discernible pattern through ten haystacks.

[Old_Salt]

It could be anything, from a fixed obstruction
(charted) to something which could have sunk and now on the seabed.

Often containers, when falling overboard at sea, tend to float at the surface for a while, but as they are weathertight and NOT watertight, they end up on the sea floor.

Navigational warnings are promulgated to vessels regarding such incidents but I am not very sure how submarines get such info.

All said and done, a internal enquiry will possibly help to ascertain the root cause. Diligent use of SONAR and proper watch keeping should help to pick up things like these, but off lately we have been seeing a lot of incidents related to inattentional blindness.

This was one case which led to a collision and casualties and one of the causes was IB.

https://en.m.wikipedia.org/wiki/Ehim...ille_collision

[comfortablynumb]

CO and XO of the USS Connecticut relieved of duty as a consequence of the accident:

https://news.usni.org/2021/11/04/uss...-of-confidence

[libranof1987]

A very resourceful article on this on CNN.

Some exceprts:

Accurate charts (with a resolution of 328 feet or 100 meters) of the sea bottom are compiled by sending surface ships over an area and bathing the bottom in sound waves -- a method called multi-beam sonar.

But the process is expensive and time consuming, leaving as much as 80% of Earth's seafloor unmapped.

In the busy South China Sea, through which a third of the world's maritime trade passes and where China has been building and militarily fortifying man-made islands, less than 50% of the sea bottom has been mapped, David Sandwell, a professor of geophysics at Scripps Institution of Oceanography in California, told CNN.

Using a method called vertical gravity grading -- taking satellite altimetry measurements of the Earth's gravitational field -- and overlaying those results with mapping of the bottom of the South China Sea, he was able to identify 27 places where the Connecticut could have hit a seamount that was not on US Navy charts.

And why these incidents are so common:

Submarines do have their own sonar, but using it comes at a price -- loss of stealthiness.

https://edition.cnn.com/2021/11/04/a...dst/index.html