5 ms·

I have no idea specifically how loud it would have been. However with some probably-reasonable guesses, it looks like it actually would have been quite loud. H

I have no idea specifically how loud it would have been. However with some probably-reasonable guesses, it looks like it actually would have been quite loud. Here's a naval study where they measured underwater sound propagation: https://www.navymarinespeciesmonitoring.us/files/7514/2780/4918/Soloway_and_Dahl_2015_Noise_Measurement_Trial_at_SSTC_5Feb2015.pdf https://www.navymarinespeciesmonitoring.us/files/7514/2780/4... They found that a 10lb block of C4 exploding produced ~210db of underwater sound. If we use that sound level as an approximation of the implosion of 200 cubic meters of submersible, which seems not completely unreasonable, then we can use the inverse square law to calculate the perceived sound far away. Halifax, NS is 1100km from the Titanic wreck. A sound that is 210db at 1 meter, is 89db at 1100000 meters. Boston is 1700km away; at that distance it would be 85db. 85db is really quite loud. You would be able to hear that, if you were underwater and paying attention. If the implosion was instead, say, 180db, then it would have been 55db in Boston harbor. Still easily detectable by instruments. For reference, when divers are performing construction using e.g. rock drills, those commonly reach 170db. The implosion of close to 200 cubic meters of air seems like it would produce a louder noise than a rock drill.

rfreiberger 3y ago
The sad part to ponder is most likely the team on the ship knew the sub was gone right when the communications was lost but kept the information to themselves.
- eterm 3y ago
  Apparently they've "lost communications" in many of their other trips, which is why also hints at why they didn't raise the alarm for many hours.
  - avgDev 3y ago
    From what I read and watched the company didn't take safety very seriously at all. A former employee claims they were fired after brining up concerns about safety. The glass apparently was not rated for the depth required to see the titanic.
  - at-fates-hands 3y ago
    Which begs the question why there were no additional safety measures put in place after so many "skin of the teeth" trips making it back. IMHO this was a get rich scheme the two founders spun up that went sideways. They spent the absolute minimum on safety and repeatedly cut corners on the sub in order to get it up and running, then charged people a ton of money to take a trip down deeper than the sub was clearly capable of going.
    - variaga 3y ago
      Look up "normalization of deviance". Perversely, a bunch of near-disasters can reduce people's concern and make them less likely to demand fixes because "it did that last time too and everything turned out okay" is a powerful rationalization.
      - tialaramex 3y ago
        Very few industries are safe enough to actually capture the "That could have been bad" events, that's what ASRS https://asrs.arc.nasa.gov/ https://asrs.arc.nasa.gov/ does for the Aviation industry (there are equivalent agencies in various other wealthy countries e.g. CHIRP in the UK) In the absence of a proper means to report "That could have been bad" as you say it can cause normalization. But it's understandable that you don't implement something like ASRS when you haven't solved most of your "That was bad" problems. If you regularly have CI failures due to the code not even compiling, "We need more unit tests" isn't top of the list of your problems.
      - toss1 3y ago
        Yup. Meanwhile, smart organizations have decades-ago stopped tracking (primarily) "Time-Lost Work Accidents" and replaced that with tracking "Close Calls". I've seen prominent signs for "N Days Since a Time Lost Accident", and more recently "X Days Since a Close Call". Sadly, it is so obvious that this CEO clown was doing everything possible to avoid experienced people ("not as inspiring to hire 50yo white guys as hiring young upstarts") so he could overrule any safety or redundancy concerns, firing people as soon as they raised things like "this porthole window is only rated to 1500m and we're going to 4000m", using cheap scrap scaffolding as ballast, and completely ignoring any kind of redundancy in case something went wrong. He seems to have gotten a just end, but his deceived customers didn't deserve that.
  - tomjakubowski 3y ago
    "losing communications" could be a broad misunderstanding of Pogue's comments https://twitter.com/Pogue/status/1671524465736335366 https://twitter.com/Pogue/status/1671524465736335366
pillefitz 3y ago
"not completely unreasonable" does a lot of heavy lifting here. I have zero intuition how the sound of an under water explosion of c4 compares to an implosion.
dadzilla 3y ago
Volume is more like a tenth of that, I think? Maybe interior dimensions 2 meters diameter and 5 meters length gives around 16 cubic meters if my math is sane (Religion major, so go easy on me if not).
cdelsolar 3y ago
my "orders of magnitude" alarm is going off here. There's no way that the implosion of a fairly small sub is going to be heard in Boston even if underwater. Something doesn't make sense here.
- Ataraxic 3y ago
  Sound does travel extremely well in water. http://resource.npl.co.uk/acoustics/techguides/seaabsorption/ http://resource.npl.co.uk/acoustics/techguides/seaabsorption... -- here is a quick calculator for sound loss by distance. I think actual geography is important too but from understanding whether or not it's hypothetically possible, it certainly looks like it. For example, at the default inputs we see .061 db/km absorption. This is at 1khz. Higher frequencies attenuated more and lower frequencies less. I have no idea what frequencies an implosion generates, but given that, a sound at 120db might still be 60db 1000km later. Certainly seems possible and in fact given what we have seen from the US Navy (detecting imploding soviet subs in the middle of the pacific ocean) it seems totally possible to me that this small sub could be detected if microphones were places in quiet spots offshore of the continental US and Canada. I think we don't have enough information to rule out that this was detectable.
codedokode 3y ago
Your calculations might be wrong. If the distance is 1000 km (1M meters), and inverse square law is correct, then the sound would become 1M*1M = 1T times more silent. 1M times smaller is 120 dB less, and 1T times smaller is 240 db less, so the amplitude of sound should be at 210 - 240 = -30dB less than threshold of hearing. Also, I wonder, if sound of explosions propagate that well, can one install multiple sensors to detect and map source of gunfire and artillery positions in realtime? (I hope I haven't disclosed NATO military secrets here).
- xsmasher 3y ago
  You just invented ShotSpotter https://en.wikipedia.org/wiki/ShotSpotter https://en.wikipedia.org/wiki/ShotSpotter

rfreiberger 3y ago

The sad part to ponder is most likely the team on the ship knew the sub was gone right when the communications was lost but kept the information to themselves.

eterm 3y ago
Apparently they've "lost communications" in many of their other trips, which is why also hints at why they didn't raise the alarm for many hours.
- avgDev 3y ago
  From what I read and watched the company didn't take safety very seriously at all. A former employee claims they were fired after brining up concerns about safety. The glass apparently was not rated for the depth required to see the titanic.
- at-fates-hands 3y ago
  Which begs the question why there were no additional safety measures put in place after so many "skin of the teeth" trips making it back. IMHO this was a get rich scheme the two founders spun up that went sideways. They spent the absolute minimum on safety and repeatedly cut corners on the sub in order to get it up and running, then charged people a ton of money to take a trip down deeper than the sub was clearly capable of going.
  - variaga 3y ago
    Look up "normalization of deviance". Perversely, a bunch of near-disasters can reduce people's concern and make them less likely to demand fixes because "it did that last time too and everything turned out okay" is a powerful rationalization.
    - tialaramex 3y ago
      Very few industries are safe enough to actually capture the "That could have been bad" events, that's what ASRS https://asrs.arc.nasa.gov/ https://asrs.arc.nasa.gov/ does for the Aviation industry (there are equivalent agencies in various other wealthy countries e.g. CHIRP in the UK) In the absence of a proper means to report "That could have been bad" as you say it can cause normalization. But it's understandable that you don't implement something like ASRS when you haven't solved most of your "That was bad" problems. If you regularly have CI failures due to the code not even compiling, "We need more unit tests" isn't top of the list of your problems.
    - toss1 3y ago
      Yup. Meanwhile, smart organizations have decades-ago stopped tracking (primarily) "Time-Lost Work Accidents" and replaced that with tracking "Close Calls". I've seen prominent signs for "N Days Since a Time Lost Accident", and more recently "X Days Since a Close Call". Sadly, it is so obvious that this CEO clown was doing everything possible to avoid experienced people ("not as inspiring to hire 50yo white guys as hiring young upstarts") so he could overrule any safety or redundancy concerns, firing people as soon as they raised things like "this porthole window is only rated to 1500m and we're going to 4000m", using cheap scrap scaffolding as ballast, and completely ignoring any kind of redundancy in case something went wrong. He seems to have gotten a just end, but his deceived customers didn't deserve that.
- tomjakubowski 3y ago
  "losing communications" could be a broad misunderstanding of Pogue's comments https://twitter.com/Pogue/status/1671524465736335366 https://twitter.com/Pogue/status/1671524465736335366

pillefitz 3y ago

"not completely unreasonable" does a lot of heavy lifting here. I have zero intuition how the sound of an under water explosion of c4 compares to an implosion.

dadzilla 3y ago

Volume is more like a tenth of that, I think? Maybe interior dimensions 2 meters diameter and 5 meters length gives around 16 cubic meters if my math is sane (Religion major, so go easy on me if not).

cdelsolar 3y ago

my "orders of magnitude" alarm is going off here. There's no way that the implosion of a fairly small sub is going to be heard in Boston even if underwater. Something doesn't make sense here.

Ataraxic 3y ago
Sound does travel extremely well in water. http://resource.npl.co.uk/acoustics/techguides/seaabsorption/ http://resource.npl.co.uk/acoustics/techguides/seaabsorption... -- here is a quick calculator for sound loss by distance. I think actual geography is important too but from understanding whether or not it's hypothetically possible, it certainly looks like it. For example, at the default inputs we see .061 db/km absorption. This is at 1khz. Higher frequencies attenuated more and lower frequencies less. I have no idea what frequencies an implosion generates, but given that, a sound at 120db might still be 60db 1000km later. Certainly seems possible and in fact given what we have seen from the US Navy (detecting imploding soviet subs in the middle of the pacific ocean) it seems totally possible to me that this small sub could be detected if microphones were places in quiet spots offshore of the continental US and Canada. I think we don't have enough information to rule out that this was detectable.

codedokode 3y ago

Your calculations might be wrong. If the distance is 1000 km (1M meters), and inverse square law is correct, then the sound would become 1M*1M = 1T times more silent. 1M times smaller is 120 dB less, and 1T times smaller is 240 db less, so the amplitude of sound should be at 210 - 240 = -30dB less than threshold of hearing. Also, I wonder, if sound of explosions propagate that well, can one install multiple sensors to detect and map source of gunfire and artillery positions in realtime? (I hope I haven't disclosed NATO military secrets here).

xsmasher 3y ago
You just invented ShotSpotter https://en.wikipedia.org/wiki/ShotSpotter https://en.wikipedia.org/wiki/ShotSpotter