3 ms·

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?

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?