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Underwater ears everywhere

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Re: Underwater ears everywhere

#21

Post by samwillis »

On this:

> Instead, the battle of submarine silence has mostly revolved around obscure technical problems of fluid dynamics, since one of the loudest noises made by submarines is the cavitation around the screw. I don't know if this is true today, but at least years ago the low-noise design of the screw on modern US submarines was classified, and so the screw was covered by a sheath whenever a submarine was out of the water.

I wander if they are Toroidal or "tipless" propellers? They create less turbulence and cavitation.

https://en.m.wikipedia.org/wiki/Toroidal_propeller

Previous posts on HN:

> Toroidal propellers turn your drones and boats into noiseless machines

https://news.ycombinator.com/item?id=34571282

> Sharrow MX-1: Tipless propeller

https://news.ycombinator.com/item?id=33949895

Re: Underwater ears everywhere

#23

Post by jcrawfordor »

darkclouds wrote: post #5

>Much more appealing is passive sonar, which works by listening for the sounds naturally created by underwater vehicles. Experts in marine biology. Reminds me of the night vision camera the british military were showing off on BBC Countryfile program. Who would have thought the military are experts in biology, but probably explains why the brits took off sunglasses in Iraq when talking to people, but the US didnt. Yo…

> I read somewhere once that a sensor, sonar or hydrophone, in UK waters could detect the sounds come from a New York harbour, which gives an insight into the distance sounds can travel underwater, but considering all the noises that can be detected, having sound processing abilities, a little bit better than something like Dolby Noise Reduction, is the key part of the underwater arms race.

I didn't really get into this in the article but there's a phenomenon called SOFAR (I think this does stand for something but the acronym is sort of a joke). It's basically a specific static water pressure (and thus depth) in which sound "ducts" sort of like how HF radio can duct in the ionosphere. As I understand it, it's not at all unreasonable for a sound in the SOFAR channel to go clear around the world. I know there are cases where hydrophones have recorded a particularly loud sound multiple times because of it coming "the long way around" as well as echo effects. Some of these sounds have been things like "perhaps the loudest sound ever produced" and are attributed to seismic phenomenon, but there are a lot of strange things going on in the ocean and hydrophones continue to provide plenty of questions for marine researchers to answer. And, of course, at least some of the IUSS sensors are very intentionally placed within the SOFAR channel to capitalize on this effect.

Re: Underwater ears everywhere

#24

Post by SkyMarshal »

manzanarama wrote: post #6

This writing is so clear and good. I can't tell you how many NYT articles I read where the paragraphs feel out of order, chopped up and there is no consistent flow. This reads very enjoyably.

That kind of modern journalism is absurd. Originally the rule in journalism was, the first paragraph must contain who, when, what, where, then subsequent paragraphs fill in the details in either chronological or logical order.

Now the first paragraph must contain an emotional human-interest style “hook” to rope in the reader, then bury the lede in some random spot in the remainder of the text, in an attempt to keep the reader searching for it, like a slot machine.

As soon as I realize that’s how something is written, I take that as signal it lacks the quality to stand alone and I discard it and move on.

Re: Underwater ears everywhere

#25

Post by grog454 »

tw04 wrote: post #18
grog454 wrote: post #14

An excellent read but one thing caught my attention: > The Navy did not withhold information on the detection for four days out of some concern for secrecy. I think it's more likely than not that the statement is correct, but what gives the author the authority to make the claim so definitively? The author's bio indicates he's a consultant and there is no indication of direct involvement in this or any other SAR effo…

>While the workings of the SOSUS and IUSS systems may be declassified, the deployments and capabilities (mostly range and computation related) of such systems most likely are not. And there is always the possibility that there is yet another system the author simply isn't aware of. But they confirmed it 4 days later - which would be admitting to its capabilities. The entire talk track of: "they kept it secret because…

And those are all valid reasons to delay release. My point is that they are not mutually exclusive with declassification, or verification that the information is OK to release publicly from a security standpoint. I'm not sure why secrecy automatically means "conspiracy theory".

Re: Underwater ears everywhere

#26

Post by andrelaszlo »

micromacrofoot wrote: post #17
darkclouds wrote: post #5

>Much more appealing is passive sonar, which works by listening for the sounds naturally created by underwater vehicles. Experts in marine biology. Reminds me of the night vision camera the british military were showing off on BBC Countryfile program. Who would have thought the military are experts in biology, but probably explains why the brits took off sunglasses in Iraq when talking to people, but the US didnt. Yo…

what’s the difference with british scarecrows? eyes or something?

They take their sunglasses off when talking to people. It's more polite.

Re: Underwater ears everywhere

#27

Post by maxbond »

jcrawfordor wrote: post #19
grog454 wrote: post #14

An excellent read but one thing caught my attention: > The Navy did not withhold information on the detection for four days out of some concern for secrecy. I think it's more likely than not that the statement is correct, but what gives the author the authority to make the claim so definitively? The author's bio indicates he's a consultant and there is no indication of direct involvement in this or any other SAR effo…

Well, the clearest source is that no one claims the information was withheld, as far as I can tell that idea was just synthesized by podcasters and internet commenters. The Navy states, the WSJ reports (probably based on the Navy statement), and the Coast Guard mention that Navy intelligence reported the possible implosion almost immediately after it was discovered. The only thing that didn't happen until four days l…

> As far as I can tell that idea was just synthesized by podcasters and internet commenters.

I don't use Twitter so can't confirm, but what I've heard in the news is that the OceanGate lawyer tweeted some vague, borderline conspiratorial stuff about not getting proper cooperation from the Coast Guard. I think the commentary people you refer to then boosted and expounded upon that idea.

ETA: Partial confirmation here https://nypost.com/2023/06/20/oceangate-adviser-rips-us-gove...

The statements quoted here don't match the description "vague and borderline conspiratorial," but they could be misinterpreted that way, and maybe there were others.

Re: Underwater ears everywhere

#28

Post by the-printer »

manzanarama wrote: post #6

This writing is so clear and good. I can't tell you how many NYT articles I read where the paragraphs feel out of order, chopped up and there is no consistent flow. This reads very enjoyably.

The fact that he publishes informative pieces at such a steady rate is remarkable as well. And the fact that he resisted to use the phrase "deep dive" in this particular one is indicative of a high level of discipline with his prose.

Re: Underwater ears everywhere

#29

Post by chongli »

SkyMarshal wrote: post #24
manzanarama wrote: post #6

This writing is so clear and good. I can't tell you how many NYT articles I read where the paragraphs feel out of order, chopped up and there is no consistent flow. This reads very enjoyably.

That kind of modern journalism is absurd. Originally the rule in journalism was, the first paragraph must contain who, when, what, where, then subsequent paragraphs fill in the details in either chronological or logical order. Now the first paragraph must contain an emotional human-interest style “hook” to rope in the reader, then bury the lede in some random spot in the remainder of the text, in an attempt to keep t…

Yeah. I can usually tell within the first couple of words if the article is worth reading or not. Anything that seems to start with a complete non-sequitur or some variant of “once upon a time” is an immediate back-button bounce for me!

Re: Underwater ears everywhere

#30

Post by tomcam »

micromacrofoot wrote: post #17
darkclouds wrote: post #5

>Much more appealing is passive sonar, which works by listening for the sounds naturally created by underwater vehicles. Experts in marine biology. Reminds me of the night vision camera the british military were showing off on BBC Countryfile program. Who would have thought the military are experts in biology, but probably explains why the brits took off sunglasses in Iraq when talking to people, but the US didnt. Yo…

what’s the difference with british scarecrows? eyes or something?

Yeah, that comment fascinated me too. I can only say that the character of British scarecrows is… very different from those in the US, although I can’t articulate one reason exactly why: https://www.google.com/search?&q=british+scarecrow&
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