News British and French nuclear submarines collide in Atlantic

[Tachyon]

MARCO ! :rofl:

 

[pattersoncr]

Were they "operating" or was one of them heading to or from port, though?



Outstanding reference to an old thread. Bravo!

I doesn't matter what they were doing. If they were submerged, they need to be in their assigned water.

 

[tblaxland]

Were they "operating" or was one of them heading to or from port, though?

Apparently Le Triomphant was returning from a 70 day tour. Whether that means it was "operating" or not, I don't know.

I doesn't matter what they were doing. If they were submerged, they need to be in their assigned water.

Wouldn't the operational zones would begin to overlap as they approach port?

Does anyone have any idea where the collision occurred? I've read "mid-Atlantic", "north Atlantic" and now Urwumpe's post make me think it was somewhere closer to the Bay of Biscay...

 

[garyw]

If I recall right each sub is supposed to be assigned a "block" of water. The idea is that incident's like the above cannot happen. If a sub falls to the rear of it's assigned block it's meant to radio someone (their upper managment?) and get the block updated.

There was an interesting documentary on the Australian submarine service and this was covered when they had engine problems and fell outside of thier assigned block.


-----Post Added-----


Bay of Biscay seems right for the collsion -> http://www.dailymail.co.uk/news/wor...es-packed-nuclear-missiles-come-disaster.html

 

[Urwumpe]

I think the collision is still hard to explain as outsider - why was the English submarine silent running in the Bay of Biscay? I doubt the report of the collision happening in 1000 ft. Beyond 800 ft, submarine hulls start "talking", I have not heard of any technology yet to distribute the increased tension inside the structures faster - you can't create flexible gaps inside a submarine hull and harder steel or Titanium would make the sound more high-pitched and easier to detect.

As the French suspected a collision with a wreck or a fishing boat initially, I would say the water was rather shallow there and both submarines pretty close to the surface. Bad conditions for passive sonar. Also, the French submarine has the frontal damage, which limits the number of collision scenarios. Also, that the French submarine has only sonar dome damage (officially) while the English submarine was immobilized, speaks for low relative velocities and rather worst-case damage on the English submarine.

A frontal collision at 20 knots looks like that:

http://www.freerepublic.com/focus/f-news/1330102/posts

As you can easily see, the impact deformed the whole submarine hull and did not even spare the massive steel structures. A tiny bit more than just the sonar dome (which is made of thin steel for US submarines, if I remember correctly, compared to fiber glass for the French submarine - but US submarines also had much more collisions and near-collisions in their submarine history). Possibly the French submarine went into the stern of the English submarine and damaged the propulsion.

I suspect, the most important evidence what happened is inside the English submarine.

What would be the normal activity in any submarine, if an unknown submerged sonar contact would appear?

 

[tblaxland]

As the French suspected a collision with a wreck or a fishing boat initially, I would say the water was rather shallow there and both submarines pretty close to the surface.

Shipping container, I read, but it would still be quite shallow.

 

[lennartsmit]

I think Doctor No is on the loose.

 

[MajorTom]

Wrong. The news about the sattelites broke first, but as far as the actual date of collision, the submarine collision happened first.

So it's su -(-20)-> sa -(-20)-> rg

Roentgen?
Roentgenium?
R-Gespraech?
Rig?

RetroGrade Planet...look out!!!

 

[T.Neo]

RetroGrade Planet...look out!!!

Hey, the moon sure looks different this morning...

 

[pattersoncr]

GaryW is pretty close to the money on this.
Submarines are assigned either a stationary geographic area to operate in or for transiting long distances, a "moving haven" is assigned.
The moving haven is a rectangular block of water constructed around a point which moves between several waypoints at a specified speed. An engineering casualty could result in the boat not being able to keep up with the moving haven and having to request more water to operate in.

The phenomenon Urwumpe is referring to is called "hull popping" it occurs during a change in depth as the pressure hull expands or is compressed. It is not due to the hull itself being compressed but due to relative motion between the hull and the interior structure. The internal structure is connected to the pressure hull via sliding fittings. If these aren't lubricated properly, they make noise as the two parts of the boat's structure move relative to each other during a depth change. Since these points are anchored to the hull, the noise radiates out into the water pretty easily. Hull popping is not much of an issue on modern submarines, especially SSBNs as the sliding joints are well designed.

The photo linked in post #25 is USS San Fransisco. She was going significantly faster than 20kts. I can't tell you how much faster. Well, I could tell you but then...(you get the idea).

 

[Urwumpe]

The phenomenon Urwumpe is referring to is called "hull popping" it occurs during a change in depth as the pressure hull expands or is compressed. It is not due to the hull itself being compressed but due to relative motion between the hull and the interior structure. The internal structure is connected to the pressure hull via sliding fittings. If these aren't lubricated properly, they make noise as the two parts of the boat's structure move relative to each other during a depth change. Since these points are anchored to the hull, the noise radiates out into the water pretty easily. Hull popping is not much of an issue on modern submarines, especially SSBNs as the sliding joints are well designed.

I mean another metallurgical phenomena actually, which does not related to the rapid change of pressure, but rather on the continued redistribution of tensions inside a material. But I don't remember the exact term - we just say the "material works" in everyday German language.

The photo linked in post #25 is USS San Fransisco. She was going significantly faster than 20kts. I can't tell you how much faster. Well, I could tell you but then...(you get the idea).

Yeah, the Captain of the submarine will look even less favorable. Speeding in a no-speeding zone...tztztztz

 

[pattersoncr]

I mean another metallurgical phenomena actually, which does not related to the rapid change of pressure, but rather on the continued redistribution of tensions inside a material. But I don't remember the exact term - we just say the "material works" in everyday German language.



Yeah, the Captain of the submarine will look even less favorable. Speeding in a no-speeding zone...tztztztz

The Soviets used to have some titanium-hulled boats (the Alfa class as well as some others). One of their oddities was that even though they were very deep-diving, they had a limited number of times they were allowed to go very deep (as compared to a steel-hulled boat that can go to test-depth as many times as desired) this was due to the poor fatigue life of titanium compared to steel.

 

[doggie015]

I think someone must have been asleep or drunk at the wheel. They have all sorts of collision avoidence systems (I hope) and how they can crash even though they have SONAR radar amoungst other things is just beyond me

 

[pattersoncr]

I think someone must have been asleep or drunk at the wheel. They have all sorts of collision avoidence systems (I hope) and how they can crash even though they have SONAR radar amoungst other things is just beyond me

They were opperating passive sonar. Submarines almost never operate active sonar. The only thing passive sonar can detect is noise put into the water by another vessel. These were both modern SSBNs, some of the quietest submarines ever built. They put very little noise into the water. They should be able to detect each other but probably not until they were at very close range. This is why waterspace management schemes are used, so that no two submerged submarines are ever in the same place at the same time.

 

[Dickie]

I'd imagine that because all the RN's SSBN movements are highly classified (and given the near paranoid lengths I know the RN goes to to keep them so, I'd imagine the French would do the same), even if they were given clearly defined blocks of sea to operate in chances are that neither the RN or the French Navy would have shared the information with each other, thus meaning they would have no idea about the other boat in the area. Add in the fact that you have two of the quietest submarines ever built on passive sonar only like Pattersoncr said, and the whole incident is actually not that surprising.

 

[NukeET]

@pattersoncr:

BZ!

Thanks for being the "been there, done that" person on this thread.

 

[bujin]

You'd have thought they would have their headlights on. I do when its stormy.

N.

Must have skidded in the wet conditions.

 

[pattersoncr]

I'd imagine that because all the RN's SSBN movements are highly classified (and given the near paranoid lengths I know the RN goes to to keep them so, I'd imagine the French would do the same), even if they were given clearly defined blocks of sea to operate in chances are that neither the RN or the French Navy would have shared the information with each other, thus meaning they would have no idea about the other boat in the area. Add in the fact that you have two of the quietest submarines ever built on passive sonar only like Pattersoncr said, and the whole incident is actually not that surprising.

Like I said further up thread, all NATO navies coordinate on waterspace management but I don't know how much France does so.
It's pretty easy to do this sort of coordination without comprimising the position of your submarines so I'd be very surprised if they didn't as well. Huge swaths of water could be reserved by one nation without telling any of the others where in the huge area your submarines were (or even whether or not they were there at all).

The only way this sort of thing happens is that someone screwed up big time. The RN submariners I've worked with have all been very good sub drivers.

@ NukeET
I wondered when you would chime in. It's not often you get to talk about submarine stuff even if it is "coner" stuff.

 

[NukeET]

@ NukeET
I wondered when you would chime in. It's not often you get to talk about submarine stuff even if it is "coner" stuff.

You beat me to the punch...but the way you argued the point I figured you for a "coner".

Seriously, I spent time forward. I was periscope assistant for battle stations (my CO liked nukes on his fire control tracking party). He also wanted us to stand watches in Sonar. I got "volunteered" for a week's worth of duty in the shack...doing the "important" jobs of resupplying the toilet paper and swapping the tapes. I could see that the "girls" get as much training as the nukes do...and learning to do that wasn't just an overnight effort. Still, they were the easiest watches I ever stood. And I got the standard ration of st from my comrades aft about the daily showers...all I could do was look at them and smile!

 

[pattersoncr]

You beat me to the punch...but the way you argued the point I figured you for a "coner".

Seriously, I spent time forward. I was periscope assistant for battle stations (my CO liked nukes on his fire control tracking party). He also wanted us to stand watches in Sonar. I got "volunteered" for a week's worth of duty in the shack...doing the "important" jobs of resupplying the toilet paper and swapping the tapes. I could see that the "girls" get as much training as the nukes do...and learning to do that wasn't just an overnight effort. Still, they were the easiest watches I ever stood. And I got the standard ration of st from my comrades aft about the daily showers...all I could do was look at them and smile!

I spent far more time standing OOD than I did as EOOW. We would often bring some of the nukes forward for Section Tracking. Some of them hated it and couldn't wait to get back aft. A few really enjoyed it though.