After the collision


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Jul 9, 2000
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>>i never knew there was such a thing<<

A lot of people don't. They were quite common on period warships but I understand that they were rarely all that effective. They were better then nothing I suppose but fairly useless when dealing with battle damage. There's also an upper practical limit on the size of the ships on which they could be used. Since they tended to be a lot more trouble then they were worth, you just don't see them in use today.
 
Oct 28, 2000
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Collision mats originated as "fothered" sails during the era of wooden fighting ships. To make one, an older sail would have thousands of short yarns hooked into its weave much the way some rugs are still constructed. The yarns were intended to provide more resistance to the flow of water when the device was in use.

A warship struck by a shot below the waterline could staunch the inflow by placing this fothered sail over the opening. In those days, a large ship had nearly 900 men, most of whom were experienced in handling canvas and rope so the task was within reason. In addition, the top speed of a wooden warship was in the same neighborhood as dead idle for Titanic. This meant the hydrodynamic forces were more manageable during the days of wooden ships.

Collision mats are still used on small boats, especially pleasure boats being salvaged. An ordinary blue plastic tarp can work wonders--but only if conditions are right. Ships the size of Titanic are another story entirely. Trying to put a collision mat in place would have been like operating a marionette on 100-foot long strings. And, Titanic was not equipped with sails large enough to do the job.

-- David G. Brown
 

Sally Butler

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I was wondering why Titanic didn't break in two where the forward first class staircase is. Isn't there more open room there when compared to the aft staircase. Both were close to an expansion joint.
It's also above boiler room four also. If I follow it right, there talk of the grand stair case breaking loose and floating free during the dive to the bottom.
I imagine the angle of the ship was important.
 
Mar 22, 2003
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Sally. The expansion joints allowed to superstructure above B deck to flex under heavy seas because the superstructure was built of relatively light materials. These expansion joints were not carried down into the basic hull girder of the vessel. It would be wrong to assume that they were points of stress concentrations within the hull girder itself and therefore the cause of a fracture even if a fracture appeared to start in the vicinity of one of them.

The entire issue of stress analysis is very complex, and depends on the distribution of weight and buoyancy as the ship was taking in more and more water in its forward compartments. The distribution would have undergone radical change once the angle of longitudinal trim of the ship started to become much more severe as well as the list to port that developed near the end.
 

Tim Foecke

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Sam,

According to blueprints we used back in 1998, the expansion joint did extend into the hull plate at C deck. As such, it would have acted as a very strong initiator for a crack when the stern came up out of the water.

Tim
 
S

Scott R. Andrews

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Tim,

I don't know where they got those prints from, but either the drawings aren't being interpreted correctly or they weren't prepared correctly. The expansion joints only extended down as far as the Bridge Deck (B), and then only through the Boat and Promenade Deck (A), and through the vertical deckhouse bulkheads and the light plating of the superstructure at the ship's sides, but not at all into the plating of B Deck itself, or beyond. The deck and sheer strakes of the shell at this level and beneath were unbroken from end to end of B Deck, and on the Shelter Deck (C) as well; the only openings through these decks were, of course, the numerous engine and boiler casings, hatchways and stairways along the longitudinal centerline; transversely, these decks were unbroken. All of this can be confirmed by examining copies of the actual H&W main construction drawings which detail the plating and framing of the aforementioned decks. The deckhouse drawing for Olympic's Bridge Deck will also confirm this, as will the drawing showing the structural details of Titanic's expansion joints.

Regards,
Scott Andrews
 
Jan 17, 2002
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I sent out copies of the Expansion Joint Details plan to Bill Garzke and a couple of others on the MFP there at CSC. I laid out the plans in September at the MFP meeting to explain the problem with the views used in 1998. When I saw the elevation plan view used for the simulation modeling only recently, it was a head-slap moment. No wonder they came to that conclusion!

Those drawings missed the details of how the expansion joint was actually designed. The kinds of stresses seen in the finite element stress simulation were artificially induced.

Tim, ask Bill Garzke for a copy of the draft paper Richard Woytowich(MFP) and I wrote for SNAME. More of the details are under wraps following the History Channel taping we did last fall. I hear the show may air in early summer. Bill also has the plans and you can see how Tom Andrews designed the joints to prevent the situation seen in the stress analysis.

Regards
Roy Mengot
 

Sally Butler

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Thanks for the replies.
It's interesting to note how one set of incorrect data could allowed a possible different simulated outcome. Does this mean the figures and assesment for the breakup will have to be reworked over again?
It's amazing how a simple oversight like this could be made by the specialists in their fields.
 
Jan 17, 2002
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Like everything in Titanic world, research is everything. The stress analysis simulation done in 1996/98 was based on the best information available. Now we have more. A big part of the peer review process for a technical paper in a professional society like the Society of Naval Architects and Marine Engineers (SNAME) has been convincing VERY senior naval architects and materials specialists that the new evidence does point to a different break-up scenario. They want to see the evidence and check the numbers.

While the break-up was incidental to the sinking, the ship was already gone from the initial damage, people still study this.

Regards
Roy Mengot
 

Tim Foecke

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Roy,

Haven't seen the newest work, so am not dissing it at all (look forward to seeing it), but I want to let you know that there is a reason that the SNAME journals have an impact factor of ZERO (impact factors are a measure of whether people are citing the work and building on it - relates to how good the journal is). Their peer review is a joke.

The 96/98 calculation, and all subsequent calculations I have seen, lacked one huge factor - a failure criterion. You have to be able to tell the finite element program that once you reach a certain stress, or better yet a certain accumulated plastic strain, the element degrades (load drops to zero) and you have a crack or hole. Without that, the steel is modeled as super strong Silly Putty. Missing in every finite element model I've seen of Titanic, because you need to run the calculation explicitly to get it to converge. Mongo computer cycles consumed.

I'm doing a model of just 1/8th of the Arizona wreck, and it has 250,000 degrees of freedom, and takes 2 days to solve. That's for each time step. Been running for better part of a year so far. Why so long? We have a failure criterion.
 
Jul 9, 2000
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>>It's interesting to note how one set of incorrect data could allowed a possible different simulated outcome.<<

Sally, this is sometimes known as the GIGO factor. (Garbage In, Garbage Out.) The simple fact of the matter is that if one is operating with incomplete data and some flawed assumptions, what's going to come out is going to be equally flawed.

The beauty of what I see here is that the people involved are aware of the problems and are working hard to correct the misconceptions. As Roy indicated, research is everything. By identifying what's wrong and what couldn't have happened, that gets us a lot closer to what really did.

I'll be looking forward to this documentary that's been mentioned and I hope somebody will announce the airing date as soon as it's known. From what I've been seeing here, the varsity team of Titanic techies have been hard at work on this. I'll have my recorder set for it.
 
Jan 17, 2002
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>> The 96/98 calculation, and all subsequent calculations I have seen, lacked one huge factor - a failure criterion. <<

The problem with any stress analysis is you can only predict the likely failure point based on the accuracy of the simulation model. We think we have the smoking gun, the body, and a couple of shell casings on the ground. We know from the previous simulation work what the general stresses were. Those are not contested. The photo evidence from the History channel expedition, and the careful mapping of the two bottom pieces, provide the physical clues no simulation model could achieve. The MFP review has been backtracking the physical evidence against the construction plans and they map nicely to discontinuities in the hull and the level of the ship's neutral axis, conditions that would only manifest themselves in the unusual position of the ship tipped up.

Regards
Roy Mengot
 

Paul Lee

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Tim, didn't the 1996/98 Finite Element Analysis factor in the breaking stress required to break Titanic's steel- I believe this was data gathered from a Charpy (sp?) Test on recovered hull fragments?

Paul

 

Tim Foecke

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Charpy data does not give an intrinsic value of the fracture energy that can be used in a finite element model. It is only used as a proof test for steels - was the reading over 20, ok then, it's good. Trouble is - 20 what? Charpy is not quantitative nor standardized.

And no, they put no fracture information whatsoever in the 96/98 model. Got that straight from the guy that ran it.
 

Jim Currie

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New boy on the block!
First: We all know the vessel went astern in any case as part of an emergency procedure to take the way off the ship. Since as was suggested in evidence, the rudder was hard over to the port side - going astern for any length of time after coming to a complete stand-still and gaining stern-way would have caused the head to swing to starboard and cant the stern to port. Continuing going astern - the vessel would eventually set into a reverse turning circle of sorts with the bow constantly swinging to starboard; increasing the water flow into the 'wound'.
This follows naturally into the speculation that the engines were run briefly ahead to cant the stern away from the ice. Why? 'Titanic' was travelling at around 37 ft/second when she hit. She would have been about 300 ft or so past the offending ice 30 seconds after the impact which would also coincide with the propellers coming to a complete stop. Ideas that her stern was 'swinging away from the berg' can easily be explained if the berg was a small one. The energy of impact would move the ice away from the ship. In addition 'narrow channel effect' would also set up a brief pressure between the ship's side and the ice forcing the two apart. Additionally, the ship would be turning very rapidly to port - in fact she would have completed 90 degrees of her tactical turning circle ( in about 1.5 minutes) before any astern thrust became positive and the vessel came to a standstill. At that point she would have been heading south. An additional minute or two running astern would have returned her heading to the planned one of around 266 T. That would occur just before she gained stern-way. After the vessel came to a complete standstill - further use of engines would be counter-productive. Astern progress was undesirable. Swinging back onto her heading using engines ahead if at all necessary could only be momentarily. After all, when the engines came to a complete halt - it was not immediately apparent that 'Titanic' was sinking. It is possible that the Master thoughts were farthest from that when he was assessing the situation. He would, however, not wish to aggravate the problem until he was fully aware of the extent of damage to his ship. I suggest he would therefore limit engine use severely.
When it is found necessary to take to the lifeboats it is obviously best to it when all way is off the vessel. Captain Smith was well aware of this. For that reason an ice free area was his best bet. He would have made the best of his known situation. I know this might cause problems with some theories but as the Scottish Bard says: 'The best-laid schemes o' mice an' men gang aft agley'.
Incidentally; Lightholler's action in going astern with a holed bow is a well known one among seafarers. Holing the bow exposes the forward collision bulkhead. Although it is designed to withstand a certain pressure at its lower third, it would be foolish in the extreme to aggravate the situation by adding to the existing damage while assisting natural pressure with forward movement.

Sailorjim
 
Jul 8, 2007
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Jim,

Some interesting ideas and suppositions. Regarding two points -

>>"Ideas that her stern was 'swinging away from the berg' can easily be explained if the berg was a small one. The energy of impact would move the ice away from the ship. In addition 'narrow channel effect' would also set up a brief pressure between the ship's side and the ice forcing the two apart."

I'm assuming that you agree that it would have to be a pretty small berg for Titanic to impart any movement to it. But leaving that "If" in there, no disagreement.

As to "narrow channel effect", are you referring to "bank effect"? If so, I don't think you can apply it here, because passing an iceberg in open water doesn't involve the same physics as running a channel, which also normally involves a fairly restricted depth under the keel. Even if it did, bank effect will normally pull the stern toward the bank, not force it away.

For those readers not familiar with this aspect of large ship handling, here's a very useful explanation of the above, with illustrations, from the Chesapeake Quarterly magazine:

http://www.mdsg.umd.edu/CQ/V04N2/side1/

(Astute readers will also note that the last two diagrams illustrate what happened between Titanic and the New York at Southampton.)

By your login name, it sounds like you may have some experience on the water, so if you feel I'm incorrect, I'd be interested in hearing your reasoning. (And I do realize that my points, if correct, don't bear heavily on your other reasoning regarding helm and engine orders.)


Regards,

Art Braunschweiger
 
Jul 9, 2000
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>>We all know the vessel went astern in any case as part of an emergency procedure to take the way off the ship. Since as was suggested in evidence, the rudder was hard over to the port side <<

A small nit, but actually, we don't really know either one. What you've said may be true, but the problem here is that we don't know down to the last detail exactly what rudder orders were given. We know from testimony from the engine room survivors that some sort of manuevering was done, but they weren't privvy to rudder orders.
 

Jim Currie

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I agree Sam and Michael but why should we dispute what was said by Hitchins - the man who was actually on the receiving end of the order? The result of the order is the crucial thing. That result was verified by the lookout who reported the ice being right ahead. I don't think there's any dispute about the vessel's head swinging to port - regardless of who heard what helm order. I of course refer to the statement of the lookout who said the head was swinging to port even before he turned back from the telephone in the crow's nest. Surely; the fact that this was an emergency turn to the left is not in dispute?
As for the vessel turning back to starboard - I again ask the question: why should she, if she is stopped dead in the water with no apparent danger nearby? Unless of course there was an additional danger which witnesses forgot to mention. I frankly cannot see any sense in moving from the known to the unknown. If I am correct, there were three clear ER orders 'Shut Dampers', 'All Stop Port and Starboard engines' and 'Full astern Port and Starboard engines'. There was evidence given by the lad in the turbine room who said the engines were ordered
ahead but there does not seem to be any conformation of this. Hitchins said he left the helm hard-a starboard. His relief at 0023hrs did not mention receiving any helm orders.

Art; I fully understand the physics involved with the 'bank' or ' narrow channel effect, having experienced this in the Suez and several other canals and rivers ( including the St. Lawrence Seaway!( yes, you are correct- I do have some experience) Unfortunately I don't have an earth-shattering revelation regarding the physics. However since there is conflicting evidence from a QM who said the berg was so close, it almost touched the aft docking bridge and an AB who swore the stern was swinging to port away from it - and, since I do know what happens during an emergency turn - I thought I'd chuck that one in and see who'nibbles'. After all there are some pretty sharp cookies on this site. Who knows? perhaps the magic of physics may yet be revealed?
I'll start the ball rolling by suggesting that yes, this was a fairly small berg and yes,the berg absorbed some of the energy and then moved away from the source(s) - initially from the impact and then from pressure caused by this giant 'paddle' which was 'Titanic's' sideways sweeping motion as she turned rapidly. Actually, I agree with the QM but I have to fence carefully on this site. Incidentally; it has been suggested that a head-on collision would have been a life-saver. Perhaps so but believe me, at 22+ knots and all that tonnage behind it , the internal damage would have been terrific. Think of a bus load of people hitting a brick wall at 25+ mph. Hitting a quay wall at 3 knots is an eye-waterer, believe me. OK! lives might have been saved but that is just speculation based on the unknown (unless someone out there knows better?).
 
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