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USS Connecticut Nuclear attack submarine underwater collision


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One Of The Navy's Prized Seawolf Class Submarines Has Suffered An Underwater Collision

https://www.thedrive.com/the-war-zone/42669/one-of-the-navys-prized-seawolf-class-submarines-has-suffered-an-underwater-collision

USS Connecticut's nuclear reactor was unaffected by the undersea accident, but the Navy won't say what exactly the submarine hit.

...11 sailors on the USS Connecticut suffered minor to moderate injuries in the accident....

Connecticut is present due to arrive in Guam today, where it is already Friday, Oct. 8. There are now reports that the collision occurred in the South China Sea....

 

You guys are getting really good at this! :D:D:D

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If they're running in poorly charted waters with no sonar active (and relying on charts alone), it could have hit a seamount.

Because they said several sailors were injured it must have been a pretty hard stop.

This quote sure sounds like they hit a big lump of uncharted rock, not another sub.

https://www.thedrive.com/the-war-zone/42669/one-of-the-navys-prized-seawolf-class-submarines-has-suffered-an-underwater-collision

 "An official who requested anonymity because they weren’t authorized to speak on the record said that the area’s topography at the time did not indicate there was a land mass in front of the boat," Military Times reported.

 

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I suppose it is possible they T-Boned a seacan right at the sail? But yeah, you would think a seacan would just bounce off otherwise. 

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25 minutes ago, Zonker said:

Because they said several sailors were injured it must have been a pretty hard stop.

 

Eh, maybe.  Article said 11 guys got bumps, bruises, and cuts.  That kind of thing can happen just from a surface ship taking a roll in heavy seas.  When the San Francisco hit a mountain, the boat went from flank speed to zero and injured almost the entire crew, broken bones galore, plus a guy who got killed.  In comparison, 11 guys with an ouchie could be anything from a light tap on the side of seamount, to hitting an unlucky whale.

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WooHoo! Sounds like Australia's first Nuked up Sub will soon be on lease to us Ozzies....available on a "scratch & dent" discount!!!

 

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A container either sits on the surface or sinks to the bottom. Neutral buoyancy is very hard to achieve. Attack subs don't be driving around on the surface or within 8' of the bottom where a container would be.

A whale is possible. But a whale, even a max blue whale is 150T max. A Seawolf sub is 9000T.

A lower speed collision with a bottom feature is far more likely. Nobody is doing flank speed in the South China Sea like the SF. They're SNEAKING around!

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They know what the bottom looks like, but perhaps not there?  We sailed with a NOAA commander that logged the bottom. . . they could draw contour lines around a car body in 10,000 feet of water.  The charts that are available to us are fantasy compared to what is available to them.

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My Dad and a few of my good engie friends worked on the Seawolf design. One of my guys was the composites engineer running the bow dome fabrication program.

It was(probably still is) the largest composite structure ever made. The typical hull section was 16" of solid fibre glass/vinylester resin. Many layups due to massive exotherm. The molds were made of steel. 

The domes of all the US subs are fibre glass so the forward looking sonar works.

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4 hours ago, Zonker said:

If they're running in poorly charted waters with no sonar active (and relying on charts alone), it could have hit a seamount.

Because they said several sailors were injured it must have been a pretty hard stop.

This quote sure sounds like they hit a big lump of uncharted rock, not another sub.

https://www.thedrive.com/the-war-zone/42669/one-of-the-navys-prized-seawolf-class-submarines-has-suffered-an-underwater-collision

 "An official who requested anonymity because they weren’t authorized to speak on the record said that the area’s topography at the time did not indicate there was a land mass in front of the boat," Military Times reported.

 

and they didn't look out of the windows 

 

 

 

ow wait

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Maybe they hit one of the chinese government's new islands... "That's funny, there was no obstruction here last week"...

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7 hours ago, CaptainAhab said:

My Dad and a few of my good engie friends worked on the Seawolf design. One of my guys was the composites engineer running the bow dome fabrication program.

It was(probably still is) the largest composite structure ever made. The typical hull section was 16" of solid fibre glass/vinylester resin. Many layups due to massive exotherm. The molds were made of steel. 

The domes of all the US subs are fibre glass so the forward looking sonar works.

And they are acoustically brilliant.

Decades ago, I was wandering around a Navy yard and came upon a bow dome, propped up on blocks. About 30 ft in diameter or so; I stuck my head under and said something just to see what the echo was like... and I then said to myself, WOW! Self, run and get your guitar and play for a while, under here. Made me wish I could play better, now I wish I could do it again.

FB- Doug

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Any reports of Spanish orca pods migrating to the South China Sea?

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On 10/7/2021 at 10:53 PM, Zonker said:

If they're running in poorly charted waters with no sonar active (and relying on charts alone), it could have hit a seamount.

Because they said several sailors were injured it must have been a pretty hard stop.

This quote sure sounds like they hit a big lump of uncharted rock, not another sub.

https://www.thedrive.com/the-war-zone/42669/one-of-the-navys-prized-seawolf-class-submarines-has-suffered-an-underwater-collision

 "An official who requested anonymity because they weren’t authorized to speak on the record said that the area’s topography at the time did not indicate there was a land mass in front of the boat," Military Times reported.

 

Hard to believe they don't have sonar active all the time.   In any event there will be a few more people looking for jobs.  

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17 minutes ago, robalex117 said:

Hard to believe they don't have sonar active all the time.   In any event there will be a few more people looking for jobs.  

Not much point spending all that money on a sub if your going to have sonar active all the time. You might as well run on the surface.

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3 minutes ago, JohnMB said:

Not much point spending all that money on a sub if your going to have sonar active all the time. You might as well run on the surface.

ok understand now.  makes sense but for somebody who does not know I thought it would be like turning off your depth sounder.

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2 minutes ago, robalex117 said:

ok understand now.  makes sense but for somebody who does not know I thought it would be like turning off your depth sounder.

I'm probably overstating it, but they do spend lots of money to keep those things hidden :)

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8 hours ago, robalex117 said:

Hard to believe they don't have sonar active all the time.

 

I learned a lot in this very interesting short article:
 

Why Multi-Billion Dollar Nuclear Submarines Still Run Into Things Underwater

https://www.thedrive.com/the-war-zone/42706/why-multi-billion-dollar-nuclear-submarines-still-run-into-things-underwater

A veteran submariner explains the challenges crews face navigating complex undersea environments that they can't even see.

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3 hours ago, Virgulino Ferreira said:

 

I learned a lot in this very interesting short article:
 

Why Multi-Billion Dollar Nuclear Submarines Still Run Into Things Underwater

https://www.thedrive.com/the-war-zone/42706/why-multi-billion-dollar-nuclear-submarines-still-run-into-things-underwater

A veteran submariner explains the challenges crews face navigating complex undersea environments that they can't even see.

I don't even need to see that.

1. They don't have windows.
2. They don't have headlights.

3. They don't use their sonar because that gives them away.

4. Sonar often doesn't work at all at most angles that are above horizontal AND below vertical--due to refraction.

So collide / allide with stuff on the way up.

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14 hours ago, JohnMB said:

I'm probably overstating it, but they do spend lots of money to keep those things hidden :)

You're not overstating it.  Active sonar is less like a depth sounder and more like a giant flashing neon sign that says "HAI GUYZ LOOK AT ME I'M A SUBMARINE."

Worse still, a sound wave can only travel so far in water, so, whatever is the maximum distance you can detect something, everyone else can hear you blasting away from twice as far off.  So you can't detect anything with active sonar that hasn't already found you ages ago.  Other than training in friendly waters, Navy submarines would only ever turn on active sonar when they know something is there and they're trying to kill it.

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7 hours ago, coyotepup said:

You're not overstating it.  Active sonar is less like a depth sounder and more like a giant flashing neon sign that says "HAI GUYZ LOOK AT ME I'M A SUBMARINE."

Worse still, a sound wave can only travel so far in water, so, whatever is the maximum distance you can detect something, everyone else can hear you blasting away from twice as far off.  So you can't detect anything with active sonar that hasn't already found you ages ago.  Other than training in friendly waters, Navy submarines would only ever turn on active sonar when they know something is there and they're trying to kill it.

I think the distances quoted in that article were for targeting. Detection can take place at far great distance, I believe.

FB- Doug

 

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I think we wait and see what happens to the CO. If he gets fired... they hit the bottom. If not they hit a foreign submarine. 

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9 hours ago, Steam Flyer said:

I think the distances quoted in that article were for targeting. Detection can take place at far great distance, I believe.

FB- Doug

 

Well, a submarine can use its active sonar to detect something further away than it can use that data for proper targeting, yes.  But as long as it's pinging out active signals, anyone else can detect that sub from further away than the sub can find anything at all, for two reasons.

One is that if a sound wave can travel a mile in the water, then it can travel half a mile to the target and half a mile back, but can be heard by the enemy a mile away.  Said sound wave would not find the enemy 3/4 of a mile away because it would dissipate before returning, but the enemy would hear it.

Two is that the echo that bounces off the target is much weaker than the original ping.  So that wave that can travel a mile, probably can't make it the half mile back to the sub anyway.

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9 minutes ago, coyotepup said:

Well, a submarine can use its active sonar to detect something further away than it can use that data for proper targeting, yes.  But as long as it's pinging out active signals, anyone else can detect that sub from further away than the sub can find anything at all, for two reasons.

One is that if a sound wave can travel a mile in the water, then it can travel half a mile to the target and half a mile back, but can be heard by the enemy a mile away.  Said sound wave would not find the enemy 3/4 of a mile away because it would dissipate before returning, but the enemy would hear it.

Two is that the echo that bounces off the target is much weaker than the original ping.  So that wave that can travel a mile, probably can't make it the half mile back to the sub anyway.

My time in the Navy was a long time ago, when digital sound processing was literally in it's infancy, and I did not spend much time in CIC. But my 2nd ship's primary task (Knox class frigate) was ASW and I recall them drawing 20 miles circles of probability. Usually they could tell which sub it was, due to already-recorded sounds of specific equipment, before they could get a targeting solution.

Surface ships have the advantage of using helos and sonobuoys, when they're serious about nailing a sub. Just keeping track of roughly where they are and where they're going, passive tracking was good for many miles. The thermocline(s) makes it more difficult, of course.

- DSK

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6 hours ago, Mizzmo said:

I think we wait and see what happens to the CO. If he gets fired... they hit the bottom. If not they hit a foreign submarine. 

Generally, it’s usually not very good for your career if you hit another sub either. 

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15 minutes ago, Monkey said:

Generally, it’s usually not very good for your career if you hit another sub either. 

Was likely common back in Cold War days to bump Soviet subs in the endless cat and mouse games. Would never be reported of course as neither navy would want anyone to know their sub was “found”. I suppose if someone is hurt in the modern FB-centric navy there is no way to keep it a secret, so…

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1 minute ago, Virgulino Ferreira said:

252790468_Screenshot2021-10-14192858.gif.9b45fd688e61070313c3314be8e0ec44.gif

 

Hitting 10,000 posts in SA is probably not good either. :D:D:D

Holy shit! I wouldn’t have even known if you hadn’t mentioned it. Too be fair, I’ve been here about 15-16 years I think. And in standard SA fashion, I only found this place because everyone was talking about my best friend’s girlfriend’s tits while she was working race committee with me. Lol!

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2 minutes ago, El Borracho said:

Was likely common back in Cold War days to bump Soviet subs in the endless cat and mouse games. Would never be reported of course as neither navy would want anyone to know their sub was “found”. I suppose if someone is hurt in the modern FB-centric navy there is no way to keep it a secret, so…

A great book for the history buffs out there is “Blind Man’s Bluff.”  It details several of those little “oopsies.”

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16 minutes ago, fastyacht said:

We are glad to see you stepping up your game recently :-P

I even made it with only one name change (I went from Bow Monkey to just plain Monkey after I got old). I’ve also made the whole run with only one month of time out when Scot got bitchy. 

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1 hour ago, Monkey said:

I even made it with only one name change (I went from Bow Monkey to just plain Monkey after I got old). I’ve also made the whole run with only one month of time out when Scot got bitchy. 

Perhaps you were being a dick. Takes quite a bit to get a timeout here. You pretty much need to run aground or hit another participant with words repeatedly. Fucking el mariachi, may he rot in invective rhetoric, had to essentially open up with a flamethrower of hate to get the boot.

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5 hours ago, Steam Flyer said:

My time in the Navy was a long time ago, when digital sound processing was literally in it's infancy, and I did not spend much time in CIC. But my 2nd ship's primary task (Knox class frigate) was ASW and I recall them drawing 20 miles circles of probability. Usually they could tell which sub it was, due to already-recorded sounds of specific equipment, before they could get a targeting solution.

Surface ships have the advantage of using helos and sonobuoys, when they're serious about nailing a sub. Just keeping track of roughly where they are and where they're going, passive tracking was good for many miles. The thermocline(s) makes it more difficult, of course.

- DSK

I was on an Oliver Hazard Perry frigate for 18 months.  I think I can count on one hand the number of times we deployed our towed array sonar.  About as often as needed to maintain qualification with it.  (The other ship I was on was an amphib, so ASW was limited to "watch out for feathers.")  I think the Navy got significantly more pessimistic between your time and mine about surface ships ever being able to find a submarine that wanted to stay hidden.  We were usually told the best way to find a sub was with another sub and the second best was with a helo.  Submariners liked to tell stories about training exercises and wargames where they'd sneak up on a destroyer and play "one ping only" with the big noisy surface ships.

If we ever have to win a shooting war with China it'll be the submarines that win it, I'm convinced.

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55 minutes ago, fastyacht said:

God spare us from a real war.

^ this ^

I believe we have some sonar techs and OS's here, so take my comments as filler until one shows up (hey @Ajax !!). All the stuff I know is pretty much public although not many of the public read stuff like Proceedings (which I don't follow as closely as I used to, sinking deeper into the laziness of retirement)

Surface ships are handicapped when it comes to hiding, but the ocean is big place. They have some advantages at sub hunting, like being able to move fast without giving up the whole game, being able to scatter active sonobuoys over a wide area, I'm not sure if the advantage in longer range weaponry is still true but the ability to shoot without giving up the game probably is.

The best way for a sub to hide is go deep and still. Preferably resting on the bottom, although there are places where they can't. Even active sonar has a hard time finding them, especially if they're below a thermocline, when they look like a bump on a rocky underwater plain. But if they can get a firing solution without going active, they still give themselves away by launching weapons. And they are, by inherent nature, more vulnerable. It doesn't take much damage to sink a sub.

In most of the publicized exercises where subs get "kills" on major targets, that sub has already been "killed" several times over by the ASW assets in that same exercise.

Still, all things considered, good subs are a great strategic asset.

- DSK

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On 10/8/2021 at 10:53 AM, Zonker said:

If they're running in poorly charted waters with no sonar active (and relying on charts alone), it could have hit a seamount.

Because they said several sailors were injured it must have been a pretty hard stop.

This quote sure sounds like they hit a big lump of uncharted rock, not another sub.

https://www.thedrive.com/the-war-zone/42669/one-of-the-navys-prized-seawolf-class-submarines-has-suffered-an-underwater-collision

 "An official who requested anonymity because they weren’t authorized to speak on the record said that the area’s topography at the time did not indicate there was a land mass in front of the boat," Military Times reported.

 

The charting produced by the "Navigation Guarantee Department of the PLA Navy is actually pretty good. I use it frequently (naturally). In fact the Navionics software for the region uses their charts. The chart agents are also extremely diligent at updating charts. I have some that peppered with the kind of magenta ink used in corrections.

If they weren't using all their available navigation aids such as sonar they were either being extremely unseamanlike or were somewhere where they shouldn't have been and didn't want anyone to hear them. Either way, pretty embarassing

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40 minutes ago, Steam Flyer said:

^ this ^

I believe we have some sonar techs and OS's here, so take my comments as filler until one shows up (hey @Ajax !!). All the stuff I know is pretty much public although not many of the public read stuff like Proceedings (which I don't follow as closely as I used to, sinking deeper into the laziness of retirement)

Surface ships are handicapped when it comes to hiding, but the ocean is big place. They have some advantages at sub hunting, like being able to move fast without giving up the whole game, being able to scatter active sonobuoys over a wide area, I'm not sure if the advantage in longer range weaponry is still true but the ability to shoot without giving up the game probably is.

The best way for a sub to hide is go deep and still. Preferably resting on the bottom, although there are places where they can't. Even active sonar has a hard time finding them, especially if they're below a thermocline, when they look like a bump on a rocky underwater plain. But if they can get a firing solution without going active, they still give themselves away by launching weapons. And they are, by inherent nature, more vulnerable. It doesn't take much damage to sink a sub.

In most of the publicized exercises where subs get "kills" on major targets, that sub has already been "killed" several times over by the ASW assets in that same exercise.

Still, all things considered, good subs are a great strategic asset.

- DSK

I might rephrase that to say: the game is already given up because the sub already knows where they are, so they might as well zoom around.

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1 minute ago, coyotepup said:

I might rephrase that to say: the game is already given up because the sub already knows where they are, so they might as well zoom around.

Well, there's "knowing where they are," and then there's having a firing solution. Then there's having a firing solution and being in position to execute it.

Subs can launch Harpoons but that definitely gives them away. They can fire old fashioned torpedoes with some chance of not doing so (I think), but their range is quite limited. An ASW ship can stay outside torpedo range and kill a sub relatively easily.

With Russian subs, you can follow them by the oil slick they leave, but that doesn't give a firing solution  ;)

27 minutes ago, fastyacht said:

Note that "strategic assettt " is Strangelovian

Well, you don't want The Other Guys to have more/better subs than us, do ya?!?

FB- Doug

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11 minutes ago, shanghaisailor said:

The charting produced by the "Navigation Guarantee Department of the PLA Navy is actually pretty good. I use it frequently (naturally). In fact the Navionics software for the region uses their charts. The chart agents are also extremely diligent at updating charts. I have some that peppered with the kind of magenta ink used in corrections.

If they weren't using all their available navigation aids such as sonar they were either being extremely unseamanlike or were somewhere where they shouldn't have been and didn't want anyone to hear them. Either way, pretty embarassing

Subs use inertial nav when submerged. Very, very, VERY good inertial nav. They keep plots of where they, or other subs have gone before, so if they didn't bump into a rock last time they followed this track, they can follow it again at high speed. Unless the bottom contour changes.....

- DSK

 

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1 minute ago, Steam Flyer said:

Subs use inertial nav when submerged. Very, very, VERY good inertial nav. They keep plots of where they, or other subs have gone before, so if they didn't bump into a rock last time they followed this track, they can follow it again at high speed. Unless the bottom contour changes.....

- DSK

 

SINS is not exactly new technology, RN bombers were using it in the late 70's and I am sure the system is more reliable when it was 40+ years ago 

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1 hour ago, shanghaisailor said:

Th

If they weren't using all their available navigation aids such as sonar they were either being extremely unseamanlike or were somewhere where they shouldn't have been and didn't want anyone to hear them. Either way, pretty embarassing

This may be the dumbest, most un informed, ignorant bordering on offrnsively stupid comment ever written on sailng anarchy :^D

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38 minutes ago, shanghaisailor said:

SINS is not exactly new technology, RN bombers were using it in the late 70's and I am sure the system is more reliable when it was 40+ years ago 

We're a long way from SINS.  When I left, the US was implementing RLGN- Ring laser gyro-navigation. That was 20 years ago.

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7 minutes ago, Ajax said:

We're a long way from SINS.  When I left, the US was implementing RLGN- Ring laser gyro-navigation. That was 20 years ago.

Commercial nav units for airplanes have had laser-ring gyros for some time now. They lose X percent accuracy per hour, you need to set them to your current lat-lon before takeoff every flight*. The rumor always was they could be much better than that, but export controls did not allow the best gyros to be sold over the shelf to all customers ;)

* they probably have an auto-sync button connected to the GPS now, assuming people still buy INS units, but back in the day it was a major screw-up to forget to set the INS or fat-finger it before takeoff, there was no way to fix it until the next flight.

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13 minutes ago, Ajax said:

We're a long way from SINS.  When I left, the US was implementing RLGN- Ring laser gyro-navigation. That was 20 years ago.

That still increments the ship's inertia... cumulative motion, right?

Don't answer if it means you have to shoot me.

- DSK

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1 hour ago, Steam Flyer said:

Unless the bottom contour changes.....

Which can happen in the South China Sea.  We were sailing in Vanuatu near an island and were in 10m of water when the charts said 20m. Whole area had uplifted in an earthquake several years previous.

 

32 minutes ago, Steam Flyer said:

That still increments the ship's inertia... cumulative motion, right?

Yes. And they are not perfect. They drift. After several days they can be 100m or so off the initial fix, depending on what sort of movements the sub has been doing.

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5 minutes ago, Zonker said:

Which can happen in the South China Sea.  We were sailing in Vanuatu near an island and were in 10m of water when the charts said 20m. Whole area had uplifted in an earthquake several years previous.

 

Yes. And they are not perfect. They drift. After several days they can be 100m or so off the initial fix, depending on what sort of movements the sub has been doing.

Sounds like a mighty fancy DR plot. (NTTAWWT)

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22 minutes ago, Raz'r said:

Sounds like a mighty fancy DR plot. (NTTAWWT)

Not really - the INS reacts to movement relative to the planet, not relative to the air or water. If you are flying/sailing east with a strong wind/current from the north, the INS figures your actual true speed and heading, not the apparent speed and heading. It knows you are going to the southeast ;)

 

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4 hours ago, shanghaisailor said:

The charting produced by the "Navigation Guarantee Department of the PLA Navy is actually pretty good. I use it frequently (naturally). In fact the Navionics software for the region uses their charts. The chart agents are also extremely diligent at updating charts. I have some that peppered with the kind of magenta ink used in corrections.

If they weren't using all their available navigation aids such as sonar they were either being extremely unseamanlike or were somewhere where they shouldn't have been and didn't want anyone to hear them. Either way, pretty embarassing

Like I'm surprised the Xi Jinping apologist thinks the US Navy was doing something wrong.  If you've been paying attention to the discussion, you'd know subs don't want anyone to hear them regardless of where they are, whether or not that's somewhere China thinks they belong.

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On 10/8/2021 at 7:29 AM, Zonker said:

A container either sits on the surface or sinks to the bottom. Neutral buoyancy is very hard to achieve. Attack subs don't be driving around on the surface or within 8' of the bottom where a container would be.

 

dunno what you mean with "sits on the surface" but this here old fart witnessed the Canadian airforce somewhere off Newfoundland (which is the normal great circle route beween the old continent and the US) bombing and shooting a number of semi to just about submerged containers which fell off a ship the day before during one of the typical winter gales ... have to say though, they first made a pass at us, contacted us asking to keep current course, we had a jolly good view on things, good show, and when they got them down they made another pass at us giving a little wing wave and a flicker of light .... from old memory, they do tend to sit just below water level depending on what's inthere.

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I guess I should have said "floats on the surface".

image.png.1452913a509a8f9c627250b2cc41b6dc.png

image.png.4dfa94f1f9095787f0e3b517338cd598.png

It's never going to be "neutral buoyancy". If the volume > weight it floats. If weight > volume it sinks.

It would be a very rare container that is EXACTLY neutrally buoyant and floats with the top barely awash.

And thus it can't be floating 2' below the water... once it's sinking, it sinks.

 

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8 hours ago, kent_island_sailor said:

Not really - the INS reacts to movement relative to the planet, not relative to the air or water. If you are flying/sailing east with a strong wind/current from the north, the INS figures your actual true speed and heading, not the apparent speed and heading. It knows you are going to the southeast ;)

 

I think the INS only knows the accelerations. Speed and direction are  computed from that. Included in the INS data are earth rotation, orbit, moon, sun, etc.  That is the problem with initializing them. An aircraft must stop on the tarmac. Cannot be updated underway unless all other motions are known. Inertial reference frame….

Subs are very good at hiding. Everything else, navigating, communicating, searching, not so much. 

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4 hours ago, Zonker said:

It's never going to be "neutral buoyancy". If the volume > weight it floats. If weight > volume it sinks.

Wouldn't every container that starts at positive buoyancy and ends at negative buoyancy be of "neutral buoyancy" at some point?

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25 minutes ago, weightless said:

Wouldn't every container that starts at positive buoyancy and ends at negative buoyancy be of "neutral buoyancy" at some point?

Well sure, by incredibly random bad luck a sub could hit a container on the way down to the bottom.

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12 hours ago, fastyacht said:

This may be the dumbest, most un informed, ignorant bordering on offrnsively stupid comment ever written on sailng anarchy :^D

Just winding people up - seems to have worked. Anyway, I would have been embarrassed if I managed to put a vessel with some of the most sophisticated nav gear on the planet onto the putty. I remember way - way back when I tapped a rock in a boat with little more than a spinning disk echo sounder and paper chart I was mortified. Sword and medals time for the watch keeper perhaps! 

 

9 hours ago, coyotepup said:

Like I'm surprised the Xi Jinping apologist thinks the US Navy was doing something wrong.  If you've been paying attention to the discussion, you'd know subs don't want anyone to hear them regardless of where they are, whether or not that's somewhere China thinks they belong.

I find it hard to understand how, by stating the facts I become a XI Jing Ping "apologist". I know how quiet and hard to find submarines are, I have been down on one (conventional one - it was a long time ago). Also other evolutions I am not about to divulge on here.

My response was purely to @Zonker about my own personal experience regarding the chart quality having used them on several China Cup HK-Dawa Wan passage races and Round Hainan Regattas. @Zonker is completely correct that charts don't always match the GPS Plotter readout. Geological effects are one reason & of course a Clipper yacht fell foul of a chart with different Datum reference a few years ago hitting an island that the plotter told them was 1 mile off their course (to the east I think) 

I am not concerned where it was or wasn't. It is still pretty embarrassing that a 'fully trained' (presumably) watch officer managed to hit something with the sort of sophisticated nav gear these puppies are supposed to have. That said no one is completely error free. I remember reading of 'Drum' being skelped by one running without lights on the Clyde. And of course the USN has a bit of recent history in hitting things - a ship off Singapore and another off (I think) Japan

SINS way back when was accurate enough ( was told by an RN Nav officer) to set position, circumnavigate and surface within 30 feet of position when the boat submerged so goodness knows how accurate the systems are these days (40+ years later) although the primary reason for the system was fire control. If you don't know where you are you don't know range & bearing to target for your missiles (back then - Polaris)

Bottom line is I am glad, damage to the boat apart, injuries on board appear to be limited to minor. We are all seamen or sailors after all.

Why do we have to make everything so frigging poitical @coyotepup 

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16 hours ago, fastyacht said:

God spare us from a real war.

So true fastyacht. My closest was Falklands where as a recently left RN guy i was half expecting a brown envelope marked OHMS  (on Her Majesty's Service) to drop through the letter box. Thankfully that was the last REAL war that the UK was involved in and I am sure the majority of Americans are glad that the US is now largely disentangled from the Middle East.

One thing I have to say I laud Americans for is how openly they thank military for their 'service'. These guys and gals, sometimes putting their life on the line - most recently and tragically the 13 service personnel trying to protect Afghan civilians at the airport - truly deserve the thanks of the general population.

Every time I hear someone say that in a report on, eg CNN, I feel like giving a thumbs up on the screen. WE should never forget them and of course we should never forget the horror which is war.

The founder of the World Trade Centres once said that the greatest barrier to world war was world trade. If he was right (& I hope he is) the amount of business interaction between China and Taiwan or China & America would hopefully mean the 'spats between these countries NEVER escalate beyond verbal and/or sabre rattling

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11 hours ago, kent_island_sailor said:
12 hours ago, Raz'r said:

Sounds like a mighty fancy DR plot. (NTTAWWT)

Not really - the INS reacts to movement relative to the planet, not relative to the air or water. If you are flying/sailing east with a strong wind/current from the north, the INS figures your actual true speed and heading, not the apparent speed and heading. It knows you are going to the southeast

Actually it was a very fancy, normally highly accurate DR.  But it was a DR.  It did measure movement relative to the planet, but you could do that while DR'ing, by accurately estimating (knowing and applying) set and drift.  SINS couldn't take "a fix" and it had to be initialized, which was essentially being told where it was.  Then it did a very fancy DR...but it wasn't actually a navigational fix and didn't count as a navigational fix (on ships that could take fixes) which was either visually, or with radar, or via LORAN/GPS.  Submerged Subs, without the periscope up, can't actually take a fix unless they turn their active sonar on (Which they almost never want to do unless they are in a phone box with an enemy sub that already knows they are there).  They are DRing, albeit, with a very sophisticated, and (normally) highly accurate ring laser gyro/SINS

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7 hours ago, weightless said:

Wouldn't every container that starts at positive buoyancy and ends at negative buoyancy be of "neutral buoyancy" at some point?

A bull is galloping west across a field. A fly is flying east across the same field. The fly smacks right into the centre of the bull’s head and immediately changes from heading east to heading west.

For a very small time, though, the fly is stopped and is going neither east nor west. So your reasoning above works.

Here’s a corollary: Between heading east and heading west, the fly is stopped. Given that he is joined to the bull at that time, is the bull also stopped?

If so, has the fly stopped the bull in its tracks?

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4 hours ago, Black Sox said:

 

If so, has the fly stopped the bull in its tracks?

And how much did the bull slow down as a result from the collision with the fly?

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And would the bull have slowed down more or less if the fly had bounced off instead of landing?

The answer will be left as an exercise for the student.

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10 hours ago, Crash said:

Actually it was a very fancy, normally highly accurate DR.  But it was a DR.  It did measure movement relative to the planet, but you could do that while DR'ing, by accurately estimating (knowing and applying) set and drift.  SINS couldn't take "a fix" and it had to be initialized, which was essentially being told where it was.  Then it did a very fancy DR...but it wasn't actually a navigational fix and didn't count as a navigational fix (on ships that could take fixes) which was either visually, or with radar, or via LORAN/GPS.  Submerged Subs, without the periscope up, can't actually take a fix unless they turn their active sonar on (Which they almost never want to do unless they are in a phone box with an enemy sub that already knows they are there).  They are DRing, albeit, with a very sophisticated, and (normally) highly accurate ring laser gyro/SINS

Good point, it IS a DR like a human would do with perfectly accurate set and drift information, it has no way of knowing it is wrong if it manages to wander off course from the gyro drift or it someone fat-fingers the fix it starts at.

The semantics that tripped me up are that when we think of boat DR, it is in large part a guess as to current and leeway, if we had any accurate information on these factors we would also have our position from the same instrument. Remember back in the day the various dodges to make up for inaccurate information? Approaching Bermuda with DR and noon-site info you might be 20-30 or more miles off from where you thought you were, but as long as you were safely north of the reefs it was fine, you just kept going until the RDF bearing was due south and turned in to St. Georges. A sun sight was not an accurate fix, but you could get accurate latitude out of it.

 

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7 hours ago, Black Sox said:

Here’s a corollary: Between heading east and heading west, the fly is stopped. Given that he is joined to the bull at that time, is the bull also stopped?

If so, has the fly stopped the bull in its tracks?

No the bull did not stop, the bull is elastic a very small part of the bull stopped.

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How does the INS know about currents? I don't think it can. Maybe they can use a Doppler current profiler on an intermittent but they are probably acoustically noisy.

It knows boat's speed, acceleration, heading, pitch, roll. It does math from a known starting point and says "you are here."

 

For our perfectly neutral buoyant container - just to beat a dead horse. If you start out positive, with a slow leak, you slowly sink in the water until your top surface is awash, and for a brief moment you're neutral. Now if you can stop the leak at that exact instant, great, you float with with neutral buoyancy. HOWEVER if a big wave pushes your container underwater briefly, the container compresses _slightly_ and loses a tiny bit of buoyancy. Then you're headed for the bottom as the container volume keeps decreasing. 

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18 minutes ago, Zonker said:

How does the INS know about currents?

 

It doesn't per se, it knows speed and heading. If you are adrift in the Gulf Stream, the boat knotmeter says 0 and the compass heading is any random direction the boat is pointing.

The INS doesn't know heading or speed through the water, it does know the speed of the boat and the direction it is moving referenced to the planet, so it might say you are headed north at 2 knots. If you have accurate heading and speed through the water info, you can do the math and find the current.

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Ha, it looks like they use doppler velocity meters as inputs. These give speed thru the water and for multi-beam systems you can tell how much you're drifting with the current.

https://www.nortekgroup.com/knowledge-center/wiki/new-to-subsea-navigation

They may also have really detailed bottom contour maps that they can follow a pre-surveyed course using a lower powered echo sounder.

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1 hour ago, Zonker said:

Ha, it looks like they use doppler velocity meters as inputs. These give speed thru the water and for multi-beam systems you can tell how much you're drifting with the current.

https://www.nortekgroup.com/knowledge-center/wiki/new-to-subsea-navigation

They may also have really detailed bottom contour maps that they can follow a pre-surveyed course using a lower powered echo sounder.

"They" may be any number of civilian subs, but I am 99.99999999999999999% sure the Navy does not go around emitting sound pulses to navigate.

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3 hours ago, Zonker said:

For our perfectly neutral buoyant container - just to beat a dead horse. If you start out positive, with a slow leak, you slowly sink in the water until your top surface is awash, and for a brief moment you're neutral. Now if you can stop the leak at that exact instant, great, you float with with neutral buoyancy. HOWEVER if a big wave pushes your container underwater briefly, the container compresses _slightly_ and loses a tiny bit of buoyancy. Then you're headed for the bottom as the container volume keeps decreasing. 

Sounds like a plausible story to me given a perfectly still and homogeneous ocean and a container with a slow leak. Maybe not the alpha to omega of container dynamics? But whadda I know? I thought the bull and fly thing was a creation story with a new universe popping into existence at the singularity. A big bang. So called on account of where the bull was headed.

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