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You'd really have to wonder how this could happen after the 2005 incident when the USS San Francisco hit an uncharted seamount in the Pacific. I claim no exper

You'd really have to wonder how this could happen after the 2005 incident when the USS San Francisco hit an uncharted seamount in the Pacific. I claim no expertise in submarine navigation/collision avoidance but it seems to me that the something that went awry with the USS San Francisco might have happened again some 16 years later. Why weren't lessons learned? I'd have thought that the detection of something as big as a seamount would have been child's play to a modern submarine and thus easily avoided. After all, detection of underwater objects is what submarines do - and one's enemy sub is a damned size smaller than a seamount. What gives? Does anyone with sufficient declassified knowledge know how this could happen? Even if everyone was being inattentive or having lunch (as they were on the USS San Francisco) then why wouldn't sophisticated detection equipment warn well ahead of any potential accident happening? I've been curious about this since that incident in 2005, now that it's happened again I'm even more so. Lastly, do we really know the extent of uncharted seamounts? Silly, question being in the negative. Perhaps, rephrased the question should be how reliable are the charts/maps submarines use these days. (This could be just my lack of knowledge, but it seems subs may be blinder underwater than my perception of them has been until now.)

jmacd 5y ago
My boat has a $1000 piece of garmin equipment which will tell me exactly how far away the landmass under me is, and has another sonar angled forward which tells me a little bit about what's coming up. It's possible that this type of sensing equipment isn't used when they are in hostile environments?
- astura 5y ago
  The entire point of a submarine is that nobody knows it's there. If they are using easily detectable equipment then people who are listening know they are there.
- fallingknife 5y ago
  Your boat is not trying to evade enemies that may want to locate and destroy it, so it doesn't matter if it is constantly emitting sound.
- chrisseaton 5y ago
  Do you really not see what the issue may be with constantly broadcasting a sonar signal would be from a military submarine?
  - hilbert42 5y ago
    See my other posts - they should not have had to have had sonar on to detect the seamount. My question, is why did the two other alternatives not work (i.e.: inertial navigation and gravity detection)?
    - chrisseaton 5y ago
      The Garmin device they’re talking about is active sonar. That means it makes a big noise. It’s like shining a light into a dark room - everyone can see where the light is coming from.
    - wil421 5y ago
      What do you keep talking about on this thread regarding gravity detection? Please link to a device that does that. Google only brings up gravity wave detectors. How is inertial navigation supposed to work for an unmapped seamount? Sure that works for known seamounts but how’s that going to help around things that move due to tectonic plates or undersea volcanos? Or in unmapped or mis-mapped regions?
      - hilbert42 5y ago
        I cannot believe there's any argument about this. There are literally thousands of references. Below, are links to the first few references that I found. Note: you'll see that in the first link in item #5 the comment about the strategic nature of this information, that means don't expect to get how-to-do-it plans from the military but you can bet your house to a brick that the military is deeply involved in gravity detection (specifically because, like inertial navigation, it's silent and doesn't broadcast its presence). Also note the dates, this stuff goes back to even before the 1970s, the technology is now very mature. "Google only brings up gravity wave detectors." See Google's patent in item #5. ___ Links as requested: 1. General Information/Overview https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_gradiometry https://en.wikipedia.org/wiki/Gravity_gradiometry https://csegrecorder.com/articles/view/magnetic-and-gravity-methods-in-mineral-exploration https://csegrecorder.com/articles/view/magnetic-and-gravity-... https://www.911metallurgist.com/blog/wp-content/uploads/2015/10/Airborne-Gravity-Gradiometry-in-The-Search-for-Mineral-Deposits.pdf https://www.911metallurgist.com/blog/wp-content/uploads/2015... http://www.ga.gov.au/pdf/RR0027.pdf http://www.ga.gov.au/pdf/RR0027.pdf 2. Commercial https://www.geologyforinvestors.com/gravity-surveys/ https://www.geologyforinvestors.com/gravity-surveys/ 3. Underwater https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.sciencedirect.com/science/article/abs/pii/S0029801815002516 https://www.sciencedirect.com/science/article/abs/pii/S00298... https://library.seg.org/doi/10.1190/geo2018-0090.1 https://library.seg.org/doi/10.1190/geo2018-0090.1 4. Military specific https://www.navysbir.com/n09_1/N091-092.htm https://www.navysbir.com/n09_1/N091-092.htm [Note the comment re the strategic nature of this information.] https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://slate.com/culture/2013/10/the-hunt-for-red-october-movie-revealed-classified-information-about-u-s-submarines-because-tom-clancy-knew-his-stuff.html https://slate.com/culture/2013/10/the-hunt-for-red-october-m... 5. Even Google has a patent! https://patents.google.com/patent/US5339684A/en https://patents.google.com/patent/US5339684A/en ____ Edit: Just found this very specific reference too, but it's not free: https://pubs.geoscienceworld.org/tle/article-abstract/34/12/1498/136542/How-do-submarines-use-gravity-gradients-to-avoid https://pubs.geoscienceworld.org/tle/article-abstract/34/12/...
- wil421 5y ago
  In submarines active sonar is rarely if ever used. It will give you away instantly to anyone around you and then you give enemies your unique sonar signature. China and Russia could easily say Seawolf XXX is the South China Sea right now pinging around. This is SIGINT 101. Submarines have the same radar and sonar we use for fishing when they are navigating public waterways and inlets. They do not use the military grade stuff in those situations.
jobeyonekenobi 5y ago
The vast majority of the time, boats don’t use active sonar. Whilst giving a high resolution view of what’s around them, it also allows any other signals collector (often defined as an enemy aggressor) to accurately pinpoint the location and deploy countermeasures, even if only updating threat assessments. Ultra detailed charts are used that have the terrain mapped. Occasional positional fixes when a boat surfaces can be used to ‘reset’ where they thought they were whilst running silent.
- hilbert42 5y ago
  "Occasional positional fixes when a boat surfaces can be used to ‘reset’ where they thought they were whilst running silent." Yeah, fair enough that makes sense, but what I've read about modern underwater inertial navigation systems is their remarkable accuracy. You'd think that any selected course for the sub would be set well within the tolerance of the inertial navigation system thus the sub would steer well clear of any known seamount. Alternatively, it was uncharted and that brings me back to the accuracy of the maps. P.S.: I'd also read somewhere that as part of the underwater navigation system that gravity detection was also used and it is sensitive enough to detect changes caused by massive nearby objects, seamounts etc. As they're passive detectors that wouldn't preclude them from being used all the time.
deleted 5y ago
[deleted]
chrisseaton 5y ago
> I'd have thought that the detection of something as big as a seamount would have been child's play to a modern submarine Would you be surprised to learn that mountains don’t make any noise?
- hilbert42 5y ago
  As per my other post, seamounts can't hide their gravity signature. Remember, we've used gravity detection for many decades for mining as mineral deposits have a different density to other surroundings which means the differences in gravity can be detected. And what I've read such detection is used as an adjunct to underwater inertial navigation systems. Perhaps, if it were not working or not installed then this accident may have exposed the fact and perhaps that's why senior offers were sacked. No doubt, we'll learn in time.
  - chrisseaton 5y ago
    Inertial navigation means judging the vector you’ve moved on from a known position. It doesn’t help you detect anything out there unless you already knew it was there! I don’t think we have perfected gravity sensors for use on submarines yet, so they would not have helped either. A lot of people on this thread seem to be sort of thinking in their heads ‘why weren’t they looking out the windows?!’ Detecting things from submarines is very hard. At the moment you can basically only listen. And listening to something that doesn’t make any noise is a challenge!
    - hilbert42 5y ago
      "I don’t think we have perfected gravity sensors for use on submarines yet, so they would not have helped either." See my list of links above, specifically item #4 Military Specific and 'Edit". It's ≈50 year old tech that's now very mature.
      - chrisseaton 5y ago
        I think these references aren't really about what you think they are. Under #4, the first one is about navigation. Again, if you don't know somethings't there, then this doesn't help you. The second one is about detecting other submarines. This was an underwater mountain. The third one is about both things, which as we just said aren't applicable, and is also about a work of fiction. The Google patent is, again, about an Inertial Navigation System. It says so in the first sentence. It doesn't do what we're talking about. The final paper, if you read beyond the abstract, talks about it just being theoretically possible. (The title with the question mark is the clue!) So we don't know if the submarine has the technology or not, or how developed it is. All that lets us know it isn’t ‘child play’. I think people are thinking of active sonar when they say that.

jmacd 5y ago

My boat has a $1000 piece of garmin equipment which will tell me exactly how far away the landmass under me is, and has another sonar angled forward which tells me a little bit about what's coming up. It's possible that this type of sensing equipment isn't used when they are in hostile environments?

astura 5y ago
The entire point of a submarine is that nobody knows it's there. If they are using easily detectable equipment then people who are listening know they are there.
fallingknife 5y ago
Your boat is not trying to evade enemies that may want to locate and destroy it, so it doesn't matter if it is constantly emitting sound.
chrisseaton 5y ago
Do you really not see what the issue may be with constantly broadcasting a sonar signal would be from a military submarine?
- hilbert42 5y ago
  See my other posts - they should not have had to have had sonar on to detect the seamount. My question, is why did the two other alternatives not work (i.e.: inertial navigation and gravity detection)?
  - chrisseaton 5y ago
    The Garmin device they’re talking about is active sonar. That means it makes a big noise. It’s like shining a light into a dark room - everyone can see where the light is coming from.
  - wil421 5y ago
    What do you keep talking about on this thread regarding gravity detection? Please link to a device that does that. Google only brings up gravity wave detectors. How is inertial navigation supposed to work for an unmapped seamount? Sure that works for known seamounts but how’s that going to help around things that move due to tectonic plates or undersea volcanos? Or in unmapped or mis-mapped regions?
    - hilbert42 5y ago
      I cannot believe there's any argument about this. There are literally thousands of references. Below, are links to the first few references that I found. Note: you'll see that in the first link in item #5 the comment about the strategic nature of this information, that means don't expect to get how-to-do-it plans from the military but you can bet your house to a brick that the military is deeply involved in gravity detection (specifically because, like inertial navigation, it's silent and doesn't broadcast its presence). Also note the dates, this stuff goes back to even before the 1970s, the technology is now very mature. "Google only brings up gravity wave detectors." See Google's patent in item #5. ___ Links as requested: 1. General Information/Overview https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_anomaly https://en.wikipedia.org/wiki/Gravity_gradiometry https://en.wikipedia.org/wiki/Gravity_gradiometry https://csegrecorder.com/articles/view/magnetic-and-gravity-methods-in-mineral-exploration https://csegrecorder.com/articles/view/magnetic-and-gravity-... https://www.911metallurgist.com/blog/wp-content/uploads/2015/10/Airborne-Gravity-Gradiometry-in-The-Search-for-Mineral-Deposits.pdf https://www.911metallurgist.com/blog/wp-content/uploads/2015... http://www.ga.gov.au/pdf/RR0027.pdf http://www.ga.gov.au/pdf/RR0027.pdf 2. Commercial https://www.geologyforinvestors.com/gravity-surveys/ https://www.geologyforinvestors.com/gravity-surveys/ 3. Underwater https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.whoi.edu/cms/files/08oceans-1_41284.pdf https://www.sciencedirect.com/science/article/abs/pii/S0029801815002516 https://www.sciencedirect.com/science/article/abs/pii/S00298... https://library.seg.org/doi/10.1190/geo2018-0090.1 https://library.seg.org/doi/10.1190/geo2018-0090.1 4. Military specific https://www.navysbir.com/n09_1/N091-092.htm https://www.navysbir.com/n09_1/N091-092.htm [Note the comment re the strategic nature of this information.] https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/1012150.pdf https://slate.com/culture/2013/10/the-hunt-for-red-october-movie-revealed-classified-information-about-u-s-submarines-because-tom-clancy-knew-his-stuff.html https://slate.com/culture/2013/10/the-hunt-for-red-october-m... 5. Even Google has a patent! https://patents.google.com/patent/US5339684A/en https://patents.google.com/patent/US5339684A/en ____ Edit: Just found this very specific reference too, but it's not free: https://pubs.geoscienceworld.org/tle/article-abstract/34/12/1498/136542/How-do-submarines-use-gravity-gradients-to-avoid https://pubs.geoscienceworld.org/tle/article-abstract/34/12/...
wil421 5y ago
In submarines active sonar is rarely if ever used. It will give you away instantly to anyone around you and then you give enemies your unique sonar signature. China and Russia could easily say Seawolf XXX is the South China Sea right now pinging around. This is SIGINT 101. Submarines have the same radar and sonar we use for fishing when they are navigating public waterways and inlets. They do not use the military grade stuff in those situations.

jobeyonekenobi 5y ago

The vast majority of the time, boats don’t use active sonar. Whilst giving a high resolution view of what’s around them, it also allows any other signals collector (often defined as an enemy aggressor) to accurately pinpoint the location and deploy countermeasures, even if only updating threat assessments. Ultra detailed charts are used that have the terrain mapped. Occasional positional fixes when a boat surfaces can be used to ‘reset’ where they thought they were whilst running silent.

hilbert42 5y ago
"Occasional positional fixes when a boat surfaces can be used to ‘reset’ where they thought they were whilst running silent." Yeah, fair enough that makes sense, but what I've read about modern underwater inertial navigation systems is their remarkable accuracy. You'd think that any selected course for the sub would be set well within the tolerance of the inertial navigation system thus the sub would steer well clear of any known seamount. Alternatively, it was uncharted and that brings me back to the accuracy of the maps. P.S.: I'd also read somewhere that as part of the underwater navigation system that gravity detection was also used and it is sensitive enough to detect changes caused by massive nearby objects, seamounts etc. As they're passive detectors that wouldn't preclude them from being used all the time.

deleted 5y ago

[deleted]

chrisseaton 5y ago

> I'd have thought that the detection of something as big as a seamount would have been child's play to a modern submarine Would you be surprised to learn that mountains don’t make any noise?

hilbert42 5y ago
As per my other post, seamounts can't hide their gravity signature. Remember, we've used gravity detection for many decades for mining as mineral deposits have a different density to other surroundings which means the differences in gravity can be detected. And what I've read such detection is used as an adjunct to underwater inertial navigation systems. Perhaps, if it were not working or not installed then this accident may have exposed the fact and perhaps that's why senior offers were sacked. No doubt, we'll learn in time.
- chrisseaton 5y ago
  Inertial navigation means judging the vector you’ve moved on from a known position. It doesn’t help you detect anything out there unless you already knew it was there! I don’t think we have perfected gravity sensors for use on submarines yet, so they would not have helped either. A lot of people on this thread seem to be sort of thinking in their heads ‘why weren’t they looking out the windows?!’ Detecting things from submarines is very hard. At the moment you can basically only listen. And listening to something that doesn’t make any noise is a challenge!
  - hilbert42 5y ago
    "I don’t think we have perfected gravity sensors for use on submarines yet, so they would not have helped either." See my list of links above, specifically item #4 Military Specific and 'Edit". It's ≈50 year old tech that's now very mature.
    - chrisseaton 5y ago
      I think these references aren't really about what you think they are. Under #4, the first one is about navigation. Again, if you don't know somethings't there, then this doesn't help you. The second one is about detecting other submarines. This was an underwater mountain. The third one is about both things, which as we just said aren't applicable, and is also about a work of fiction. The Google patent is, again, about an Inertial Navigation System. It says so in the first sentence. It doesn't do what we're talking about. The final paper, if you read beyond the abstract, talks about it just being theoretically possible. (The title with the question mark is the clue!) So we don't know if the submarine has the technology or not, or how developed it is. All that lets us know it isn’t ‘child play’. I think people are thinking of active sonar when they say that.