I think we’ve found as much as we can about the breakup as far as the wreckage. The biggest thing now is de-coding what we’ve observed and trying to figure out what it means.This is one for the all the technical experts on here.
I know that in the mid-late 1990s there was a considerable amount of investigation conducted upon the wreck that looked into the breakup but do you think they missed anything ?
Is there anything specifically about the breakup still to learned from careful investigation of the wreck or has this went as far as it can conceivably go ?
I'm unsure why you're counselling me on the topics of a conspiracy theory and an expansion joint. I didn't talk about either of them. You must be thinking of the person ApwbD1912, who posted before me.The V break is not a conspiracy, Bill. If we carefully examine the evidence of eyewitnesses and know the main strength parts of the ship. we can build a minds-eye picture of what happened.
First: a ship is designed like a girder with a top and bottom flange. The top "flange" is the heavy strake (line ) of shell plating, which in the case of Titanic ran from bow to stern at the deck-edge of Deck C. it is called the "sheer strake"
The bottom "flange" was a little more complicated. it consists of the vertical plate keel the plate on top of the keel, the plate on the bottom of the keel and the two bottom shell plates (Garboard strakes) running from bow to stern on each side of the keel. Do you visualise this?
When a ship's stern rises out of the water.... even by a small amount, the bow dips and a stress called the "hogging stress" is imposed on a point on the upper edge of the sheet strake...the top edge of the plate is in huge tension. Consequently, the bottom "flange" is in compression.
If the tension on the upper edge of the sheer strake is great enough, it will break violently and vertically at the point of greatest stress...and usually with a very loud "BANG".
However, if the ship is up right, without a list to port or starboard, the hogging stress is shared equally between the port and starboard top edges of the sheer strake and the plates will stay intact much longer...perhaps even long enough for the ship to sink intact.
Now imagine what would happen if the ship was not only tipped by the bow but heeled over to port.
I suggest to you that in this case, the greatest stress would be on the upper edge of the starboard side sheer strake and it would part with a loud BANG. This would immediately transfer the load to the port side sheer strake and at the same time, allow a massive volume of sea water to enter the hull as the starboard side break propagated downward.
Thus, the sequence of events would be:
1...Starboard side sheer strake breaks and the hull cracks vertically downward at the break location allowing huge volumes of sea water to enter the compartments in way.
2... Ship sinks faster and port side heels even more to port imposing full stress on the port side sheer strake which then breaks with a BANG
3.... The sudden added weight in the area of the forward end of the engine room causes the bottom "girder to fail in 2 places and a sectio of the Double bottom tears free from the hull... The hull is now in two parts...the aft part returns to the upright position while the forward part continues to heel to the left and spirals bow downward toward the sea bed.
To answer you questions:
There was most certainly a V break but the Expansion Joints played no part in the main hull failure.
When the bow started down ward it did so with a forward as well as down ward movement, this gave the impression of a wave passing along the boat deck from bow toward the stern.
When the internal parts of the hull were suddenly inundates at the moment of initial failure, the flood water displace air trapped inside the compartments being flooded. In the case of the engine rooms and boiler rooms the sudden escape of trapped air through ventilator shafts would expel anything in the way such as soot, coal or Lightoller and Colonel Gracie.
The antics of the forward section as it broke loose and rolled would also confuse thos looking in the direction of the funnels visible above the surface.
Just a few thoughts.
This is how I see the first part of the hull failure sequence, Sam...a wee bit inaccurate but i'm sure you will see what i'm getting at.V-break theory? Two views of what could be considered a V break: A break that looks like the letter \/ or a break that looks like an inverted letter /\.
So which one?
Jim's description appears to be /\ caused by hogging stress failure. (I happen to agree with this view.)
The other V break would be a sagging stress failure in the double bottom and look like \/. (I see no physical reason why this would happen.)
Probably right about mixing-up postings.I'm unsure why you're counselling me on the topics of a conspiracy theory and an expansion joint. I didn't talk about either of them. You must be thinking of the person ApwbD1912, who posted before me.
I understand the construction of the ship, and how structures fail.
In your rendition of events, it isn't clear why the keel broke into pieces and tore free from the hull. Water in the engine room would not do that. Flooding into a ship compartment below sea level simply equalizes that part of the ship with the sea around it. Flooding takes away buoyancy, leaving the dead weight of the iron. The iron there could support itself and more. Maybe you're saying that the top-down break went all the way down to and through the keel?
Also, I wish that people would clarify when they are talking about a "V" break. Is it the shape of the opening that forms, or the shape of the ship once it breaks? From descriptions that people have given, it usually sounded as if they were talking about the shape of the ship: bow up, stern up, and down in the middle, like a V. Your description sounded the opposite.
If you're asking about witnesses in the lifeboats, I don't know that level of detail. I will say that it was a few women, and the women's testimonies are mostly rubbish because they were clueless about ships, sea life, etc. It is the men's testimonies that I rely more upon...although some of them are pretty bad, too. "Consider the source" is a good thumbrule for listening to people's testimonies.Do we know which sides of the boat deck those who claimed that it rose were situated?
If you're talking about net pressure acting on the hull, that it true. But if you look at the bending moments on the hull girder, the flooded compartments would create increased stresses on the sheer strake, the same as if weight was added to those flooded compartments equal to the volume water that flooded in. And that can easily be proved.A flooded compartment actually has less stress on it.
Above sea level, yes. Below sea level, no. Below sea level, water entering the ship does not add weight; it simply equalizes with the surrounding water.If you're talking about net pressure acting on the hull, that it true. But if you look at the bending moments on the hull girder, the flooded compartments would create increased stresses on the sheer strake, the same as if weight was added to those flooded compartments equal to the volume water that flooded in. And that can easily be proved.
I’m almost certain that those on the ship who talked about the deck rising were on the starboard side. If the rising sensation was only felt by those on the starboard side, is it safe to formulate the idea that the port list was simply worsening, causing the starboard side (which was partially under water) to lift up before sinking again?If you're asking about witnesses in the lifeboats, I don't know that level of detail. I will say that it was a few women, and the women's testimonies are mostly rubbish because they were clueless about ships, sea life, etc. It is the men's testimonies that I rely more upon...although some of them are pretty bad, too. "Consider the source" is a good thumbrule for listening to people's testimonies.
I do know that the guys who were trying to get the collapsible lifeboats going mentioned that the bow went under, started forward, and then seemed to rise again, enabling the men to finish getting the lifeboat's fastenings cut loose. Also, men on the starboard side like R. Norris Williams had the #1 funnel fall at them; he escaped narrowly, but his father was killed by it. That's the little bit of port-vs.-starboard stuff that I know from that moment. Usually all of the testimony from that time is about water ("it washed me off" or "I jumped"), so there was not a lot of talk about the angle of the ship at that instant.
The forward flooding was controlled. in that it entered the hull between water tight bulkheads. These kept it confined to one side of each space between these bulkheads.. The rate of flooding in each space was directly related to the size of the hull breech. However, unlike sudden vertical opening in the hull, it was not catastrophic. Nor was it "added weight". it was a loss of buoyancy. There is a difference. You can add weight to a ship until she reaches her Margin Line and she will remain afloat. Normally, weight is added to a vessel in a very controlled mannerOkay, I see what you're saying. You're pointing out a top-down break, followed by a side-to-side tearing of the keel--from starboard to port. You're also referring to the "V" shape as applied to the shape of the break ("The starboard side forward and aft of the initial fracture is increasingly free to move away from the point of fracture...forming an ever-widening vertical V" is how you describe it). Everyone else on this site appears to be using the "V" to mean the shape of the ship.
As I said before, flooding in the engine room and boiler room 1 is not "adding weight" in a concentrated fashion, any more than it was doing so in all of the compartments forward, which were already flooded. (None of them broke due to "weight" of the water inside, right?) Water coming in simply takes away buoyancy, equalizing the pressure of the inside of the hull to the pressure outside of it. A flooded compartment actually has less stress on it. For example, when the wreck of the submarine USS Scorpion was found, all compartments were destroyed (due to implosion) except the forward torpedo room, which had its hatches open. Experts surmised that a torpedo casualty blew open the hatches, and of course killed everyone in the compartment so that there was nobody to shut the hatch. Enough additional flooding of the operations compartment was enough to send the sub downward to the depths, where the pressure instantly crushed each air-filled compartment (including the ops compartment) one at a time. The torpedo room was equalized with the ocean; all stress was off of it. It was dead weight. That is also why the flooded portion of bow half of the Titanic is in such good shape on the ocean floor.
I still think that there was a top-down failure at the same time as a keel buckling failure. I think that there had to have been both, for a few reasons. (1) Deckhouse debris and the two keel pieces are together, and sitting in the direction that the ship had been coming from. Top and bottom pieces being together says something. I haven't heard a reasonable alternative explanation yet. (2) At the moment that there was excessive tensile stress at the top of the ship, there was also compressive stress at the keel (simple beam bending). A double bottom 5 feet thick, containing all of those beams and plating, would not compress more than a few inches; it was quite a rigid set-up. An immense compression would not (and did not) smash/crush/mangle the keel pieces smaller as their failure mode. The only way that the keel structure could fail under such a huge compressive stress state is to buckle, which amounts to part of the structure 'jumping suddenly out of the way'. (3) There was apparently an instantaneous, huge flooding event that increased the pressure in the ship at that time--different from all the previous flooding. I don't think that top-down cracking could cause that. However, I'll concede that a wholesale shattering of the side of the hull (after bulging excessively) below the waterline could do so. But such bulging and shattering was not possible with the keel intact--but would be quite expected once two keel pieces got thrown out of the way. (4) There had to arise some kind of driving force to make the ship thrust forward and momentarily bob upward at the bridge. If only a top crack snapped open, there would be equal and opposite reaction movements on each side of the split, and if the bottom (keel) stayed the same length (or merely cracked), it would add no asymmetric force to the ship's gross movement one way or the other. All of the top-down-only scenarios are pretty symmetrical fore to aft. By contrast, if the keel buckled at the same time as the top parts split, it would allow for the conversion of some of the stern's potential energy into some kinetic energy moving forward, due to a pivoting action. (To use your door analogy, picture a very heavy 3-hinge door having its top and bottom hinge pins pulled, so that when you opened the door, both the top and bottom came free at the same time. It would pivot about its center hinge until it ran out of room to move by hitting the floor.) Back to the ship. That additional stern force on the bow might have doubled the speed of the (maybe 1.5-knot?) Southwest drift that the ship probably already had. The ship moved about 1600 feet (almost 2 ship lengths) from the time of the deckhouse debris and keel pieces dropping, to the location of the 5 boilers and first engine cylinder dropping. A velocity of 3 knots would cause the ship to go that distance in 5 minutes. Besides any continued inertial drifting after "All Stop", the only "power source" for moving the ship that far in such a short time was the energy of the break-up. I think that there had to be an unbalanced forward-applied force in the mix.
That is technically true, but In Naval Architecture, and ship stability considerations, they are treated in a different way.The loss of buoyancy is the exactly same as the added weight of water that enters a compartment. It's just another way of looking at things. Adding 10,000 tons of water to a compartment say by pumping it in through a hose produces the exact same result as letting 10,000 tons of water flood the compartment through an opening in the hull. The vessel will trim down to the exact same configuration.