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

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

#101

Post by imwillofficial »

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?

Short answer to your question is no.

Longer answer: A cheap commercial sonar isn’t going to find a submarine, even if you know where you’re looking. Submarines are incredible stealthy, and the ocean greatly effects sonar effectiveness, especially from the surface. Due to how it works, surface sonar is nearly useless when trying to locate a submarine.

A popular joke was for us to surface right in the middle of a fleet during war games, or sneak up behind them and take pictures of people smoking and send them to the surface ship’s captain just to mess with them.

With things like towed sonar arrays, and sonar bouys, the playing field can be evened out a bit, but in all the war games I was in, the surface guys could not find us even we told them exactly where we were.

Now imagine that, with an inexperienced submarine crew doing testing, and a surface ship practically incapable of keeping track of us…

“CON, ESM, EMERGENCY DEEP! Hold high signal strength contact bearing 087!”

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

#102

Post by ttepasse »

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…

That the collision happened close to port is weird in itself. France has its SSBNs stationed south of Brest; the UK to the west of Glasgow. One would assume the individual routes to the patrol areas would be rather different. What would the HMS Vanguard do less than a days travel from Brest?

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

#103

Post by bell-cot »

imwillofficial wrote: post #101
bell-cot wrote: post #94

Earlier quoted context omitted.

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?

Short answer to your question is no. Longer answer: A cheap commercial sonar isn’t going to find a submarine, even if you know where you’re looking. Submarines are incredible stealthy, and the ocean greatly effects sonar effectiveness, especially from the surface. Due to how it works, surface sonar is nearly useless when trying to locate a submarine. A popular joke was for us to surface right in the middle of a fleet…

I'm thinking more of a busy shipping area, and the essential mission is only to provide a surface exclusion zone, which a submarine could take advantage of as it (say) enters / leaves a harbor. The sonar's job is to broadcast a "your (say) Coast Guard Auxiliary moving exclusion zone is right here" signal to the sub's passive listening equipment. The CG Auxiliary guys up top don't even know if a real submarine is in the area - vs. a practice mission, or maybe the Navy is sailing a cheap decoy past some Russian fishing boat that's lingering where it ain't welcome.

(From exDM69's comment, I'll figure that the active sonar's power needs to be dialed way down. The theory that a sub's fancy listening gear could get a good fix on a sonar signal that's too weak to give a usable reflection seems hand-wave plausible to a landlubber.)

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

#105

Post by sxates »

Johnny555 wrote: post #98

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 ca…

Its a little weird that the catastrophe described is about the warheads, not the loss of the whole crew. Though I'm sure it's about a billion dollar loss of hardware as well.

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

#106

Post by imwillofficial »

bell-cot wrote: post #103
imwillofficial wrote: post #101

Earlier quoted context omitted.

Short answer to your question is no. Longer answer: A cheap commercial sonar isn’t going to find a submarine, even if you know where you’re looking. Submarines are incredible stealthy, and the ocean greatly effects sonar effectiveness, especially from the surface. Due to how it works, surface sonar is nearly useless when trying to locate a submarine. A popular joke was for us to surface right in the middle of a fleet…

I'm thinking more of a busy shipping area, and the essential mission is only to provide a surface exclusion zone, which a submarine could take advantage of as it (say) enters / leaves a harbor. The sonar's job is to broadcast a "your (say) Coast Guard Auxiliary moving exclusion zone is right here" signal to the sub's passive listening equipment. The CG Auxiliary guys up top don't even know if a real submarine is in t…

Sonar has to hit something and bounce back.

Detecting sonar doesn’t.

No hand waving needed.

When transiting places like that, there is either an escort, or the sub is surfaced, or the sub moves reaaally carefully. All depends on the mission.

Check out the book “Blind Man’s Bluff” for more info.

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

#107

Post by kragen »

gpm wrote: post #93
kragen wrote: post #75

Earlier quoted context omitted.

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...

I meant "a region", not "a regions". Oops.

Thanks for the FAS link!

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

#108

Post by hindsightbias »

postalrat wrote: post #97
hindsightbias wrote: post #31

Earlier quoted context omitted.

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?

If it sat still for hours and a shallow depth, thermodynamics is thermodynamics.

Very different from the idea of passing tons of seawater through a reactor and dumping it out. It's not like a jet engine flying through the sky.

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