In 2009, Two Nuclear Submarines Collided Under the Sea (2016) • Hacker News Board

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#91

Post by imwillofficial » Tue, Aug 31, 2021, 2:02 AM UTC

omni wrote: post #47

gpm wrote: post #29

Earlier quoted context omitted.

Surely not. The submarine with the larger more sensitive instruments in a quieter environment ought to be able to detect sound levels below that which their active opposition can. If X amount of noise-energy hits the submarine, it only reflects Y Both of these weigh in favor of the submarine detecting the searcher before the searcher detects the submarine.

I'm fully willing to admit I'm talking out my ass here, but does it not make sense to assume that both a) the active drones are going to be much faster than a submarine trying to maintain silence, and b) there are likely to be many drones converging from different directions if they're searching a known submarine parking spot? Still seems like advantage drones to me

No such thing as a sub parking spot. Think of the ocean and sound conductance like layers of a cake.

I’m sure drones will get there, but right now advantage is the subs

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#92

Post by imwillofficial » Tue, Aug 31, 2021, 2:04 AM UTC

zoomablemind wrote: post #23

Surprisingly, no side was assigned the blame for the collision. Unlike air traffic or surface navy accident. One had a conning tower damage, the other had a bow damage; both were supposedly slow-moving at the moment. Is there such thing as right of way for subs?

No right of way, but there are movements called “baffle clearing” where you check your blind spots before moving. Due to the fickle nature of the mistress that is the ocean, sometimes even properly executed movements can still be dangerous.

Submarine life is insanely dangerous.

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#93

Post by gpm » Tue, Aug 31, 2021, 2:08 AM UTC

kragen wrote: post #75

omni wrote: post #25

Earlier quoted context omitted.

If you can hear them, they've already found you

The path loss for active sonar is, logarithmically, twice the path loss for passive sonar. If the signal is 0 dB at 1 meter, it will be -40 dB at 10 km away (barring SOFAR, a regions these submarines probably try to avoid, and ignoring the reflections off the surface and seafloor), and the reflection (assuming an isotropic reflector) will be -80 dB. At 100 km, it's -50 dB and -100 dB. So, if both sides can detect a -…

> barring SOFAR, a regions these submarines probably try to avoid, and ignoring the reflections off the surface and seafloor

For anyone wondering what is being discussed here, this is a great document (SOFAR is a sound channel): https://man.fas.org/dod-101/navy/docs/es310/SNR_PROP/snr_pro...

Turns out sonar signals don't actually move in straight lines...

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#94

Post by bell-cot » Tue, Aug 31, 2021, 2:28 AM UTC

imwillofficial wrote: post #88

wil421 wrote: post #69

Earlier quoted context omitted.

The escort ships would know exactly where the sub they are escorting is. They could easy see the bottom or a massive blob passing underneath (an unknown sub) or even an undersea mountain. You don’t need enough resolution to tell if it’s a sub or even a whale you just need enough to say watch out. My middle of the road Garmin can see 1,100 feet deep in salt and side scan 500 feet in either direction. You can see botto…

No the escort ships do not know exactly where the sub is. On my first submarine duty, we nearly surfaced right in the path of our escort. We had to dive hard to avoid getting run over. “Clearing baffles” is not an exact science.

If the surface escort (whether a fancy warship, or a modest Harbor Patrol boat) was running a cheap commercial sonar set in active mode, and the sub's orders were "stay right under your escort, so long as its course seems reasonable" - with details of 'reasonable' spelled out in written orders - would that be easy to execute without incident?

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#95

Post by archsurface » Tue, Aug 31, 2021, 3:08 AM UTC

Under the sea? What were they doing there?

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#96

Post by bambax » Tue, Aug 31, 2021, 4:10 AM UTC

puglr wrote: post #80

traeregan wrote: post #79

Earlier quoted context omitted.

> reconstruct a conversation by analyzing the movement of the glass on a window to the room where people are talking May I please have a link to more information? I wasn't able to find anything, and this is very interesting.

"reconstruct conversation glass vibration" brings up a lot of relevant results from a 2014 story from MIT. Sounds like it works in principle with any medium that can have its visible vibrations monitored (bag of chips is the main example, but they talk about other options such as plants or a glass of water).

Yes I think that's what I was referring to; I may have confused glass and chips but it seems it works with either medium.

https://news.mit.edu/2014/algorithm-recovers-speech-from-vib...

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#97

Post by postalrat » Tue, Aug 31, 2021, 4:43 AM UTC

hindsightbias wrote: post #31

changoplatanero wrote: post #20

Earlier quoted context omitted.

There is a technique for finding nuclear submarines from space by using satellites to look for the hot water exhaust from the nuclear reactors.

Closed cycle steam generation plants aren't going to exhaust much. They can't filter seawater fast enough for use and you couldn't run seawater through those systems w/o messing them up. Wastewater is probably cooled before release.

Wouldn't cooling something with water warm up the water?

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#98

Post by Johnny555 » Tue, Aug 31, 2021, 5:45 AM UTC

each carrying 4 and 6 nuclear warheads respectively. Losing such apocalyptic firepower on the ocean floor would have been a catastrophe. However, nuclear warheads are not susceptible to “going off” as a result of a collision.

What is the catastrophe if this had happened? The weapons won't explode. Is it the danger that they'll leak their radioactive fuel, or that they'll be captured by some enemy power before they can be retrieved (if they can be retrieved at all)?

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#99

Post by exDM69 » Tue, Aug 31, 2021, 5:49 AM UTC

bell-cot wrote: post #94

imwillofficial wrote: post #88

Earlier quoted context omitted.

No the escort ships do not know exactly where the sub is. On my first submarine duty, we nearly surfaced right in the path of our escort. We had to dive hard to avoid getting run over. “Clearing baffles” is not an exact science.

If the surface escort (whether a fancy warship, or a modest Harbor Patrol boat) was running a cheap commercial sonar set in active mode, and the sub's orders were "stay right under your escort, so long as its course seems reasonable" - with details of 'reasonable' spelled out in written orders - would that be easy to execute without incident?

That would avoid incident but the sub might as well run surfaced with active sonar on.

The active sonar from the escort would reveal the sub it is escorting to any passive observers. It would need a directional sonar (not a cheap commercial sonar) and avoiding prop noise that can also reflect off the sub.

And if all subs were escorted this way, the navies of adversaries would quickly pick up this habit.

Re: In 2009, Two Nuclear Submarines Collided Under the Sea (2016)

#100

Post by baobabKoodaa » Tue, Aug 31, 2021, 8:55 AM UTC

nradov wrote: post #49

baobabKoodaa wrote: post #37

Earlier quoted context omitted.

> There are no parking spots. Ballistic missile submarines conducting deterrence patrols are assigned to large areas covering hundreds of square nautical miles ... So a collision in open ocean is theoretically possible but highly unlikely. It's misleading to describe collisions as "theoretically possible" when we have evidence that these collisions have occurred. The fact that collisions have occurred makes me think…

You missed the point. The collision covered in this article occurred relatively close to port, not during an open ocean patrol. A ballistic missile submarine's position isn't completely random, but they do move around somewhat randomly to reduce the risk of detection. They intentionally avoid repeating movement patterns or lingering in the same spot. And this also reduces the risk from spies on land. If a spy sees th…

> You missed the point. The collision covered in this article occurred relatively close to port, not during an open ocean patrol.

So you're saying the collision _didn't_ occur at a time when the sub was trying to stay hidden, you're saying that the operators could have / should have used active sonar? Is that it?

Look, either the sub was trying to stay hidden at the time it accidentally collided with another submarine, or it wasn't trying to stay hidden. In either case it didn't do a good job. If it wasn't trying to stay hidden, then it shouldn't have collided. If it was trying to stay hidden, then its location was not as unpredictable as it should have been.