I was listening to a BBC broadcast about the missing submersible. If I heard correctly, they said that under the surface of ocean water, radar does not work and neither does satellite communications, but sonar does in a very limited way.
Is that correct? And if it is, why, scientifically, is it correct?
If it is correct, what does it say about military submarines?
but sonar does in a very limited way.
As I understand it, it has to do with the thermocline.
https://en.wikipedia.org/wiki/Thermocline
In the open ocean, the thermocline is characterized by a negative sound speed gradient, making the thermocline important in submarine warfare because it can reflect active sonar and other acoustic signals. This stems from a discontinuity in the acoustic impedance of water created by the sudden change in density.
The lost sub is probably in deep water (it was a Titanic wreck tourist operation) finding it with surface sonar would be difficult if not impossible.
Is that correct? And if it is, why, scientifically, is it correct?
If it is correct, what does it say about military submarines?
It says that you ought to do your own DuckDuckGo or Google or Bing searches instead of just asking on this forum.
Also, military subs can use VLF antenna, but only at depths of less than 100'. That's why subs in WWII were vulnerable, because they had to stick an antenna ABOVE the surface to send/receive. That's what makes sub commanders special - once they get orders, no one's looking over their shoulder.
I was listening to a BBC broadcast about the missing submersible. If I heard correctly, they said that under the surface of ocean water, radar does not work and neither does satellite communications, but sonar does in a very limited way.
Is that correct? And if it is, why, scientifically, is it correct?
If it is correct, what does it say about military submarines?
RADAR does not work at all under water, SONAR is similar but has limitations.
Thermoclines are a very real thing, and cause strange effects with sound. Think of them as "rivers" of water of a different temperature (normally colder) running through the ocean. And in short, the barrier between the two temperatures can cause strange reflections. Ask any diver and they have likely experienced thermoclines first hand.
It tends to look kind of "shimmering", and the moment you pass the water can drop 10 degrees in an instant. Then passing through the other side rise again just as much. The barriers between the temperatures can refract or deflect the SONAR, unlike the air on RADAR.
Military submarine communications is a bit different. And there are two main systems used.
The first is via radio or satellite, where they have to rise to a shallow depth and extend an antenna. The other is via ELF or Extremely Low Frequency radio. This is a kind of radio that does penetrate the oceans, but requires a lot of power to do so which is why it is only transmitted from ground stations. And as it operates at between 3 and 20 Hz (compare to 87-108 MHz for FM), it is too slow to pass actual information to the subs.
So how it is used is that the Navy will use one of their ELF transmitters to send a coded signal to the subs at sea. Simply a short code of a few letters and numbers that will give instructions. It may range from ordering a single sub to surface and contact them via radio, to all of them moving to their fail-safe points and prepare for nuclear war.
From an article:
In underwater disasters, a crew unable to communicate with the surface relies on banging on their submersible's hull to be detected by sonar.
Why it wasn't tethered to the ship is beyond me.
It was running a tour of the Titanic Wreck which is at a depth of 13,000 feet.
They probably can't maintain a tether that long. And even if they could, if they are would be getting close to the wreck and going around it a tether could get tangled in the wreck at that would be very bad.
If a USN or other NATO submarine were to get close enough (a kilometer more or less, depending upon a number of environmental factors) it is possible to communicate by Phone. No wires, the sound transmits through the water.
The tourist sub may not be equipped with such a device; but it might, as they could talk to the "mother ship" when they are close to the surface during hook up, or soon after release from the harness that lifts the sub from deck to ocean and vice versa.
Also, a remotely operated submersible, at least one of which may be used in an attempted rescue, could provide a communications device that could be attached to the exterior of the sub and hear them through the hull, or possibly the view portion.
I don't know how the carbon fiber composite hull might convey sound compared to a metallic hull.
If a USN or other NATO submarine were to get close enough (a kilometer more or less, depending upon a number of environmental factors) it is possible to communicate by Phone.
If the tourist sub is on the bottom, it's more than a kilometer deeper than a Navy sub can get. US navy subs have a max depth around 3K feet, the Titanic is at 13K feet.
If the tourist sub is on the bottom, it's more than a kilometer deeper than a Navy sub can get. US navy subs have a max depth around 3K feet, the Titanic is at 13K feet.
My math may be a bit off, but I believe that is within a kilometer, 1,000 meters,
I believe I mentioned using a remotely operated DSR, that can be sent out through a torpedo tube to attach a "phone" to the exterior of the sunken sub.
My math may be a bit off, but I believe that is within a kilometer, 1,000 meters,
Your math is a lot off. 10,000 feet is 3048 meters, a hair over 3 kilometers.
Yup. Somehow in my head, I must have multiplied by 3, twice. I should have used pencil ✏ and paper 📃 😅
However, they did use RPV DSRVs to find that missing F35, and recover with cables similar to those sent to the site of the missing sub. The F35 was in significantly deeper water.
The F35 is about the same size as the missing sub; but made of "stealth" materials.
They had USN SSNs in the vicinity "helping" in ways not specified in open sources.
The sub could be lifted by the lifting eye built-in to the sub. Or by using flotation bags. Or by releasing the external ballast.
The sub could be lifted by the lifting eye built-in to the sub.
They are bringing a crane that can lift it from a depth of 20,000 feet.
Of course they have to find it first. And by the time the crane arrives everyone onboard would have run out of oxygen.
They are bringing a crane that can lift it from a depth of 20,000 feet.
My understanding from radio reports is that a ship capable of conducting the rescue has been there since Monday. The USN had flown out 3 sets of cables* that they have used to replace the DSRVs (Deep Sea Rescue Vessel); identical to those used to recover the F35 that fell overboard in the Pacific Ocean and sank into deeper waters than the missing sub.
Of course they have to find it first. And by the time the crane arrives everyone onboard would have run out of oxygen.
That may be a moot point. As of 1600 Hours Greenwich Zulu 22 June 2023, it was reported they found a "debris field" that authorities (USCG) believe may be the missing sub. No specifics, nor even indications of why they suppose this.
No specifics, nor even indications of why they suppose this.
They found 5 major pieces of the sub 1,600 feet from the Titanic from an implosion.
The report I just saw said that the tour didn't guarantee you would see the Titanic Wreck and while it cost $250,000 it came with a non refundable policy.
Theycan't complain though, can they? Those billionaire arseholes paid for an immersive Titanic experience. Can't get much more realistic than being dead at the bottom of the Atlantic Ocean due to catastrophic engineering failure compounded by unbelievable hubris and severe overconfidence.