4 ms·

Stupid question, perhaps: was/it possible for this sub to have any kind of beaconing or communication system that works at depth? It seems like one of this fir

Stupid question, perhaps: was/it possible for this sub to have any kind of beaconing or communication system that works at depth? It seems like one of this first things I'd investigate before deciding to build a sub.

mikestew 3y ago
Summary: water attenuates radio signals, and a 4Km cable is going to be way heavy and subject to currents.
- tguvot 3y ago
  what about fiber ? <4kg per km. throw at end powered buoy. maybe inflatable to hold more of it. currents still will be mess, but with lower than copper weight you could have a few km slack
  - teraflop 3y ago
    I think your assumptions are unrealistic. A fiber optic cable weighing 4kg per km with no other reinforcement or protection would be extremely fragile. According to my back-of-the-envelope math, using the density and tensile strength of typical glass, it would have a breaking load capacity of around 10 newtons (roughly 2 pounds of force). Even a steel cable with the same weight would only be about 20 times stronger.
    - tguvot 3y ago
      4kg/km it's not for clean glass fiber. it's fiber drop cable, in whatever plastic sleeving + a couple of steel strands for some added rigidity/structure. there are also versions with kevlar braiding to protect core and improve resilience.
- ZanyProgrammer 3y ago
  Well they paid the price for that bit of efficient thinking, didn’t they?
- nerpderp82 3y ago
  Sound carries very efficiently in water. https://oceanexplorer.noaa.gov/explorations/sound01/background/acoustics/acoustics.html https://oceanexplorer.noaa.gov/explorations/sound01/backgrou... https://news.cornell.edu/stories/2005/02/secrets-whales-long-distance-songs-are-unveiled https://news.cornell.edu/stories/2005/02/secrets-whales-long... The sub should have had an acoustic transponder that broadcast telemetry which could also be used to locate it.
- silisili 3y ago
  Seems you're right, I just was searching how the military does it and...it's not great. Came across https://en.wikipedia.org/wiki/Communication_with_submarines https://en.wikipedia.org/wiki/Communication_with_submarines . So perhaps the best you could do here are something like emergency buoys that either one can record data on or perhaps automated recording some stats/location/whatever that can be released in an emergency and send a broadcast once topside?
nradov 3y ago
The sub had a limited acoustic telemetry system for transmitting to the host ship. That signal was lost, so presumably the sub has suffered some type of serious failure.
- silisili 3y ago
  Thanks! I've read a few articles in passing, and none mentioned anything like that. Doesn't sound promising now...
vlod 3y ago
I was wondering how naval submarines work when they get in trouble. I would expect to see some sort of emergency button (internally) that you could press, that would release some sort of buoy, that would float to the surface and start transmitting with gps etc. I think that would help narrow down the search. The buoy would be in an external container (to prevent pressure problems), with explosive bolts or something to release.
- mustacheemperor 3y ago
  From what I understand, naval submarines typically have a signaling device called an EPIRB mounted in such a way that it's released automatically if the sub dives significantly below crush depth and/or if a switch isn't activated on some set interval. Then it pops up on the surface and says "Hi, wreck here." I don't think the former system would have worked here anyway, since the sub is supposed to get very close to the bottom.
  - bombcar 3y ago
    They had this but there were problems with it, if I recall correctly. So it would be disabled in "times of war" or whatever because if it accidentally popped off it was not a good time for you.
    - shadowgovt 3y ago
      "Hi, depth charge here."
- shadowgovt 3y ago
  > I was wondering how naval submarines work when they get in trouble. Naval subs in trouble? They go "forever on patrol." A naval sub is an espionage watercraft; signaling an emergency isn't exactly in the playbook for most of their mission cycle. ;)
  - vlod 3y ago
    The alternative is death of 134 odd people. Not ideal. :/ I would expect some e2e encryption satellite communication, however that might be still traceable to the enemy listening posts. Man, I now need to watch "Hunt for Red October" again [0]. lol [0] https://www.youtube.com/watch?v=3C2tE7vjdHk https://www.youtube.com/watch?v=3C2tE7vjdHk
jonathankoren 3y ago
Yes, you'd think emergency procedures would be at the top of the list right after you made a viable pressure vessel. They obviously didn't do this. They previously lost the sub for five hours. Why this doesn't have an emergency buoy, or an locator beacon that works when the ship surfaces, I don't know.

mikestew 3y ago

Summary: water attenuates radio signals, and a 4Km cable is going to be way heavy and subject to currents.

tguvot 3y ago
what about fiber ? <4kg per km. throw at end powered buoy. maybe inflatable to hold more of it. currents still will be mess, but with lower than copper weight you could have a few km slack
- teraflop 3y ago
  I think your assumptions are unrealistic. A fiber optic cable weighing 4kg per km with no other reinforcement or protection would be extremely fragile. According to my back-of-the-envelope math, using the density and tensile strength of typical glass, it would have a breaking load capacity of around 10 newtons (roughly 2 pounds of force). Even a steel cable with the same weight would only be about 20 times stronger.
  - tguvot 3y ago
    4kg/km it's not for clean glass fiber. it's fiber drop cable, in whatever plastic sleeving + a couple of steel strands for some added rigidity/structure. there are also versions with kevlar braiding to protect core and improve resilience.
ZanyProgrammer 3y ago
Well they paid the price for that bit of efficient thinking, didn’t they?
nerpderp82 3y ago
Sound carries very efficiently in water. https://oceanexplorer.noaa.gov/explorations/sound01/background/acoustics/acoustics.html https://oceanexplorer.noaa.gov/explorations/sound01/backgrou... https://news.cornell.edu/stories/2005/02/secrets-whales-long-distance-songs-are-unveiled https://news.cornell.edu/stories/2005/02/secrets-whales-long... The sub should have had an acoustic transponder that broadcast telemetry which could also be used to locate it.
silisili 3y ago
Seems you're right, I just was searching how the military does it and...it's not great. Came across https://en.wikipedia.org/wiki/Communication_with_submarines https://en.wikipedia.org/wiki/Communication_with_submarines . So perhaps the best you could do here are something like emergency buoys that either one can record data on or perhaps automated recording some stats/location/whatever that can be released in an emergency and send a broadcast once topside?

nradov 3y ago

The sub had a limited acoustic telemetry system for transmitting to the host ship. That signal was lost, so presumably the sub has suffered some type of serious failure.

silisili 3y ago
Thanks! I've read a few articles in passing, and none mentioned anything like that. Doesn't sound promising now...

vlod 3y ago

I was wondering how naval submarines work when they get in trouble. I would expect to see some sort of emergency button (internally) that you could press, that would release some sort of buoy, that would float to the surface and start transmitting with gps etc. I think that would help narrow down the search. The buoy would be in an external container (to prevent pressure problems), with explosive bolts or something to release.

mustacheemperor 3y ago
From what I understand, naval submarines typically have a signaling device called an EPIRB mounted in such a way that it's released automatically if the sub dives significantly below crush depth and/or if a switch isn't activated on some set interval. Then it pops up on the surface and says "Hi, wreck here." I don't think the former system would have worked here anyway, since the sub is supposed to get very close to the bottom.
- bombcar 3y ago
  They had this but there were problems with it, if I recall correctly. So it would be disabled in "times of war" or whatever because if it accidentally popped off it was not a good time for you.
  - shadowgovt 3y ago
    "Hi, depth charge here."
shadowgovt 3y ago
> I was wondering how naval submarines work when they get in trouble. Naval subs in trouble? They go "forever on patrol." A naval sub is an espionage watercraft; signaling an emergency isn't exactly in the playbook for most of their mission cycle. ;)
- vlod 3y ago
  The alternative is death of 134 odd people. Not ideal. :/ I would expect some e2e encryption satellite communication, however that might be still traceable to the enemy listening posts. Man, I now need to watch "Hunt for Red October" again [0]. lol [0] https://www.youtube.com/watch?v=3C2tE7vjdHk https://www.youtube.com/watch?v=3C2tE7vjdHk

jonathankoren 3y ago

Yes, you'd think emergency procedures would be at the top of the list right after you made a viable pressure vessel. They obviously didn't do this. They previously lost the sub for five hours. Why this doesn't have an emergency buoy, or an locator beacon that works when the ship surfaces, I don't know.