61–70 of 108 posts
Are they really not detectable from space?
Subs would be detectable using magnetometers, except that they have electromagnets in them to hide their magnetometer footprint. Still, this is not perfect.
Large subs have somewhat detectable gravitometric footprints that could be observed from space, indeed.
Are they really not detectable from space?
Why do you think they would be detectable from space? That doesn't make any sense.
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There is a technique for finding nuclear submarines from space by using satellites to look for the hot water exhaust from the nuclear reactors.
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.
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You don’t need drones. Planes and helicopters already drop sonar buoys for the exact reason you stated. A better solution would be for an escort when they get into crowded lanes. Surface ships can use active sonar to scan for other subs while being some what close to their sub. The only problem is other listeners can pick up on what is reflecting off your active sonar as well. Also the subs try to avoid ever being de…
It's not like any navy has spare surface warships with active sonar available to escort submarines through constricted navigational channels. There are also environmental concerns with active sonar due to impacts on marine life, especially cetaceans. During peacetime it's usually only allowed in designated exercise areas.
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How would the proximity sensors work? The can’t go active sonar…
Low power high freq radio waves? These should rapidly attenuate underwater, so not much of giveaway, but could be enough for proximity scans around the sub. Is there some spectrum of emissions from an even stealthy sub, some kind of "local presence"? The immediate massive obstacles would result in distortions to such a self-presence profile. So the sensors could be trained to detect such local distortions, almost lik…
Turns out, this has been modeled already (2007):
[1]:https://www.photonics.com/Articles/Fish_Navigation_System_Re...
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It's not like any navy has spare surface warships with active sonar available to escort submarines through constricted navigational channels. There are also environmental concerns with active sonar due to impacts on marine life, especially cetaceans. During peacetime it's usually only allowed in designated exercise areas.
I have sonar on my kayak. You can certainly use a power that is not going to hurt sea creatures. A lot of Navy ships including submarines have off the shelf sonar as well as military sonar. I’ve seen a pic of a sub with Raymarine radar they use when surfaced in channels. The subs don’t want to use their own military grade stuff because then the enemies have the frequency signature so they use off the shelf for naviga…
https://www.frontiersin.org/articles/10.3389/fmars.2017.0029...
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Optical, perhaps? How much light is at these depths? How do the subs avoid terrain?
Subs avoid terrain using charts and dead reckoning, including inertial navigation systems. They typically come to periscope depth occasionally to get a navigational fix. In 2005 a US submarine allided with an underwater mountain due to a navigational error. https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/ There is little or no light at typical operating depths. Lidar can work to a limited extent in some w…
And, of course, it's an active sensor. An adversary could detect the emitted light.
So the submarines can't use active sonar, because their number one priority is to avoid detection... but then these subs are all parked in the same "parking spots" in the ocean. If the favored parking spots for submarines are so rare and small that collisions happen more than once, surely that undermines their stated number one priority of remaining hidden? If someone wanted to locate enemy submarines, surely they co…
Sounds like the FAA altitude problem all over again. As altimeters got more accurate, the odds that you were flying at exactly 28000 feet went up. If an air traffic controller fucks up and puts two planes at 28000ft, they can now collide because they're ±10ft instead of ±200ft. That was the RCA of that mid-air collision over Brazil a while back. The more you try to control a thing the more problems you can have. A pa…
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I have sonar on my kayak. You can certainly use a power that is not going to hurt sea creatures. A lot of Navy ships including submarines have off the shelf sonar as well as military sonar. I’ve seen a pic of a sub with Raymarine radar they use when surfaced in channels. The subs don’t want to use their own military grade stuff because then the enemies have the frequency signature so they use off the shelf for naviga…
That's simply not how it works. The active sonar on your kayak has nowhere near enough power or resolution to detect a military submarine at sufficient range for reliable collision avoidance. Due to the inverse square law, active sonars have to put out a huge amount of power to detect submarines at any useful range. This is a proven risk to marine life. https://www.frontiersin.org/articles/10.3389/fmars.2017.0029...
My middle of the road Garmin can see 1,100 feet deep in salt and side scan 500 feet in either direction. You can see bottom features and schooling fish. The higher end stuff is so much better.
and
Re >> "At some point, the two navies compared notes"
I get that ballistic submarines want to stay secret and use passive sonar, instead of active sonar. But I also would have thought - if a submarine mysteriously ran into something under water that they did not expect to be there, that they'd start taking a more "active" approach to figuring out what was going on. It'd be like if I tried to walk blindfolded through a large & empty conference room: if I bumped into a whole wall after walking only 3 or 4 steps, I'd be very confused!