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Topic: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: KBJCpilot
Posted 2012-10-14 20:28:18 and read 6653 times.

"A U.S. Navy Aegis cruiser collided with a nuclear-powered submarine during exercises off the East Cost on Saturday, collapsing the sonar dome on the cruiser and possibly causing other damage, but no injuries, U.S. Navy officials said."

Two CO's will be kissing their careers goodbye.

http://www.reuters.com/article/2012/...idUSBRE89D00X20121014?feedType=RSS

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: boacvc10
Posted 2012-10-14 21:14:30 and read 6619 times.

This puzzles me. I'm only going on by some cursory knowledge, but wouldn't the Sub commander have had a report from sonar that a ship was so nearby, as he surfaced? I understand that (ala, perhaps Titanic) a warship cannot turn on a dime, and hopefully tried to make a turn away from a direct collision, but how much time would they have had to respond, and could the cruiser have made it?

I read elsewhere that the sonar dome of the ship is totally unpressurized due to contact, and that would have been about the depth of the submerged deck of the sub (guess!) so do we have a case of the ship running over a sub (joke!) or a ship and a sub meeting side by side. In that case, the sub hull is a pretty tough cookie then. But it would have left a big dent, right?

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: NBGSkyGod
Posted 2012-10-15 04:48:31 and read 6432 times.

Quoting KBJCpilot (Thread starter):
Two CO's will be kissing their careers goodbye.

It will depend on who was not where they were supposed to be. BZ to the watches for seeing the parascope before the collision giving the captain enough time to at least slow the ship down. Hopefully they get some awards for their actions.

At least they can still pull over and exchange insurance information.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: Revelation
Posted 2012-10-15 05:03:35 and read 6422 times.

Quoting boacvc10 (Reply 1):
wouldn't the Sub commander have had a report from sonar that a ship was so nearby, as he surfaced?

Playing armchair admiral, I'd have to say this is mostly on the sub commander. Both ships certainly should have been darn aware of each other's presence, but it was the submarine commander's decision to surface that's the proximate cause of the incident.

Quoting boacvc10 (Reply 1):
I read elsewhere that the sonar dome of the ship is totally unpressurized due to contact, and that would have been about the depth of the submerged deck of the sub (guess!) so do we have a case of the ship running over a sub (joke!) or a ship and a sub meeting side by side. In that case, the sub hull is a pretty tough cookie then. But it would have left a big dent, right?

That really depends on exactly how fast they were going when the collision happened.

The sub hull is indeed tough, but more so the inner hull (which is what protects the crew) rather than the outer hull (which is used to store ballast water needed to raise or lower the sub).

It sounds like a glancing blow, otherwise we'd be reading of how the cruiser's propellers sliced away at the sub.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: MarSciGuy
Posted 2012-10-19 08:42:45 and read 5771 times.

Quoting boacvc10 (Reply 1):

This puzzles me. I'm only going on by some cursory knowledge, but wouldn't the Sub commander have had a report from sonar that a ship was so nearby, as he surfaced? I understand that (ala, perhaps Titanic) a warship cannot turn on a dime, and hopefully tried to make a turn away from a direct collision, but how much time would they have had to respond, and could the cruiser have made it?

I read elsewhere that the sonar dome of the ship is totally unpressurized due to contact, and that would have been about the depth of the submerged deck of the sub (guess!) so do we have a case of the ship running over a sub (joke!) or a ship and a sub meeting side by side. In that case, the sub hull is a pretty tough cookie then. But it would have left a big dent, right?

While I'm not a military person and thereby don't know the specifics on cruiser/destroyer propulsion, BUT many modern Civilian ships are equipped with bow thrusters or Azi Pods (Azimuthing Pods) that allow for a great level of maneuverability. A NOAA Ship I was aboard a decade ago had both and instead of doing the Williamson turn they would spin the pods forward and full power, stopping the 274' ship going 16 kts in a ships' length... it was rarely done other then actual MOB drills or incidents, as that maneuver puts a huge amount of stress on the structure and fittings of the vessel.

Cheers! (now back to cleaning the house as the baby is about to return from an appt   )

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: astuteman
Posted 2012-10-19 10:21:28 and read 5717 times.

Quoting Revelation (Reply 3):
but it was the submarine commander's decision to surface that's the proximate cause of the incident.

As a technicality, the article doesn't say he decided to "surface", but was at periscope depth.

Whether the cruiser knew the sub was there before they saw the periscope is a good question - the alarm being raised by the sighting of the periscope suggests they might not have, but we don't know.
I can't imagine the sub didn't know there was a cruiser steaming at some speed within stone throwing distance

Gut feel? Just rank bad seamanship on the part of the sub's OOW.
Seen that before.........  
Quoting boacvc10 (Reply 1):
I read elsewhere that the sonar dome of the ship is totally unpressurized

It will probably be free-flood (be full of sea-water), to allow the incoming sound waves to propagate right through the medium of the water until they impact the transducers..

Rgds

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: ThePointblank
Posted 2012-10-19 17:25:17 and read 5568 times.

Quoting MarSciGuy (Reply 4):
While I'm not a military person and thereby don't know the specifics on cruiser/destroyer propulsion, BUT many modern Civilian ships are equipped with bow thrusters or Azi Pods (Azimuthing Pods) that allow for a great level of maneuverability. A NOAA Ship I was aboard a decade ago had both and instead of doing the Williamson turn they would spin the pods forward and full power, stopping the 274' ship going 16 kts in a ships' length... it was rarely done other then actual MOB drills or incidents, as that maneuver puts a huge amount of stress on the structure and fittings of the vessel.

The Tico's are traditionally laid out; no bow thrusters, twin screws. Warship construction have not fully embraced Azi Pods or bow thrusters yet.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: BladeLWS
Posted 2012-10-19 18:09:06 and read 5551 times.

Quoting ThePointblank (Reply 6):

The Tico's are traditionally laid out; no bow thrusters, twin screws. Warship construction have not fully embraced Azi Pods or bow thrusters yet.

Ticos have a traditional layout but that's where the similarity ends. Those ships are powered by gas turbines and variable pitch propellers, you can get immediate full astern power with a few seconds of going from flank to full back. IIRC you can stop a ship that size within a boat length or two but if you're to close it doesn't really matter.

There was a breakdown command on the sub that caused this to happen. Sonar must validate the area as clear, and the OOD or CO will visually confirm the surface picture via the scope before coming up, unless it's an emergency blow.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: ThePointblank
Posted 2012-10-19 19:25:20 and read 5527 times.

Quoting BladeLWS (Reply 7):
Ticos have a traditional layout but that's where the similarity ends. Those ships are powered by gas turbines and variable pitch propellers, you can get immediate full astern power with a few seconds of going from flank to full back. IIRC you can stop a ship that size within a boat length or two but if you're to close it doesn't really matter.

There was a breakdown command on the sub that caused this to happen. Sonar must validate the area as clear, and the OOD or CO will visually confirm the surface picture via the scope before coming up, unless it's an emergency blow.

Indeed, but the the more exotic azi pod thrusters have not fully been embraced by warship designers.

Warship designers have used Voith Schneider Propellers in the past, but realistically, only for ships that require lots of maneuverability and can sacrifice speed, such as minesweepers. A big switch has been for newer designs to use Integrated electric propulsion, which considering the increasing electrical demands on warships today, is a necessary switch.

Quoting BladeLWS (Reply 7):
There was a breakdown command on the sub that caused this to happen. Sonar must validate the area as clear, and the OOD or CO will visually confirm the surface picture via the scope before coming up, unless it's an emergency blow.

Indeed. I will not be surprised to see the CO of sub to be removed from duty at the very minimum. The captain of the cruiser will probably still continue to serve on the ship.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: astuteman
Posted 2012-10-21 00:17:08 and read 5242 times.

Quoting boacvc10 (Reply 1):
In that case, the sub hull is a pretty tough cookie then. But it would have left a big dent, right?

Didn't see this earlier. But no. The sonar dome would be lucky to scratch the sub's hull, much less dent it. Might pull some tiles off  

It could easily make a nice mess of the free-flood fore and aft ends, hydroplanes, rudders, bridge-fin (that'll be the "sail" to all you gents from across the pond   ), or casings (if US SSN's had any)

Rgds

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: Darksnowynight
Posted 2012-10-21 05:04:07 and read 5162 times.

Quoting NBGSkyGod (Reply 2):

At least they can still pull over and exchange insurance information.

Nahh, that'll buff right out.

Quoting Revelation (Reply 3):

It sounds like a glancing blow, otherwise we'd be reading of how the cruiser's propellers sliced away at the sub.

Well... Are the cruiser's screws made of the same metal? I always thought that there they traded some brute strength away to get a more corrosion resistant metal. I always figured that's why they were made (or is just coated with) from brass.

Quoting astuteman (Reply 5):
Whether the cruiser knew the sub was there before they saw the periscope is a good question - the alarm being raised by the sighting of the periscope suggests they might not have, but we don't know.
I can't imagine the sub didn't know there was a cruiser steaming at some speed within stone throwing distance

Yeah, you'd think a cruiser's screws would be audible through the sub's hull even without needing the sonar suite for that one. Should have been louder than a train wreck at that range.

Quoting astuteman (Reply 5):

It will probably be free-flood (be full of sea-water), to allow the incoming sound waves to propagate right through the medium of the water until they impact the transducers..

Hmmm.. Interesting. I had previously assumed it was pressurized to avoid balance issues. But I guess having a water medium right up to the 'phones probably does save quite a lot of processing power what with not having to compute out the massive speed of sound differences between water and sea level air. Good point.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: astuteman
Posted 2012-10-21 07:22:15 and read 5116 times.

Quoting Darksnowynight (Reply 10):
I had previously assumed it was pressurized to avoid balance issues. But I guess having a water medium right up to the 'phones probably does save quite a lot of processing power what with not having to compute out the massive speed of sound differences between water and sea level air. Good point.

A reference....

http://en.wikipedia.org/wiki/Bulbous_bow

Quote:
The entire compartment is flooded with water and the acoustic window of the bulb is made of fiber-reinforced plastic or another material (such as rubber) transparent to underwater sounds as they are transmitted and received.

Amazing what you can find out from Wiki....  

Rgds

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: KC135TopBoom
Posted 2012-10-28 16:38:41 and read 4383 times.

Is it just me or does this collission sound similar to the USS Greenville (SSN-772) and the Ehime Maru back in 2001?

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: woodreau
Posted 2012-10-28 21:55:41 and read 4283 times.

Quoting Darksnowynight (Reply 10):
Yeah, you'd think a cruiser's screws would be audible through the sub's hull even without needing the sonar suite for that one. Should have been louder than a train wreck at that range.

It depends if the prairie masker was in use or not. If it was in use the acoustic signature of the surface ship is significantly reduced.

If its an exercise, there is usually a designated safety course for the participants to come to if there is an unexpected sighting of a periscope or submarine. And during routine operations there usually are designated operating "water space" areas that are supposed to separate submarines from other submarines and surface ships laterally vertically and in time.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: ThePointblank
Posted 2012-10-29 02:36:22 and read 4210 times.

Quoting KC135TopBoom (Reply 12):
Is it just me or does this collission sound similar to the USS Greenville (SSN-772) and the Ehime Maru back in 2001?

Very similar. Also similar in terms of what happened between the USS Hartford and USS New Orleans.

Topic: RE: Well, That Sucks- Aegis Vs. Fast Attack Collide
Username: L-188
Posted 2012-10-29 11:32:06 and read 4057 times.

Interesting thing is that histirically there are many documented US-Soviet sub collisions

And those are just the ones we know about


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