Time of the break

[Erik Wood]

Great info Parks thanks.

 

[Erik Wood]

I did some basic calculations to check on that 78 point whatever and how it would stand up. I still can't figure out where that comes into play or how that number came up. With weight of water and it's spreading the ship was loosing to much to much buoyancy to achieve an angle of 78 some degrees. More over if the ship increased it's angle by 5.67 degrees every 45 minutes then the ship should have only acheived about a 17 degree angle.

Now if we are referring to after the break when the stern was completely detached from the bow....I didn't do any calcualtions on that I will have to work on it. But I think 78 degrees is stretching it.

I can't help but wonder if it is in one the many mistakes that the Discovery Channel made in there attempt to cover the thing.

 

[Stephen Stanger]

(by the ref that Parks made to "hull girder", would that be another term for keel?)

I'm seeing some light here but I still find it hard to see that the keel would have snapped at less then 35 degrees. The skin and the decks maybe but that keel must have had a dash of brittleness to it.
In all the research done, is there no definite conclusion as to the angle of the break then? I checked Mengot's site which was very enlightening but there was no angle alluded to.

 

[Michael H. Standart]

Hi Stephen, about all we can say at this point is what positively could not have happened. This is what Edward Wilding actually said on the matter;

The Commissioner: It was thought the boilers had got loose from their seats.

20916. (Mr. Laing.) Yes. (To the Witness.) Is that a reasonable theory? - When the ship was about 35 degrees by the head.

20917. That might have happened? - When the bow was down so that her stern was up, so that the slope fore and aft of the ship was about 35 degrees.

Mr. Wilding knew the Olympic class ships about as well as anybody could and if he was of the opinion that the ship would have to reach an angle of 35 degrees for the boilers to come loose, you can bet he did his math to back it up.

As to the keel breaking, keep in mind that a lot of the ships weight is supported by the water. When the stern reared up out of it, that support was gone. As tough as the keel was, it simply could not hold up to the enormous bending loads placed on it which may well have approached 65,000 pounds per square inch. Brittleness in this case...if any...would have been a non-factor.

 

[Parks Stephenson]

<font color="#000066">(by the ref that Parks made to "hull girder", would that be another term for keel?)

Stephen,

No, The keel forms one component of the hull girder. The best way to describe the hull in terms of structural strength is to liken it to a box-shaped girder. No one component of the structure provides all the longitudinal strength...the deck, side and bottom plating make up a considerable portion of the structure's strength. Stresses resulting from a transverse bending moment are typically less severe than those due to a longitudinal bending moment, so the design of a hull girder provides more strength along the longitudinal axis.

The most significant modifications to the box-like structure are the tapered ends at both bow and stern, as well as the sheer of the deck. The form is further modified by the turn of the bilge and the fairing of the bottom toward the ends. Because the streamlined underwater form is symmetrical about the longitudinal centreplane, a rigid centreplane girder is required that runs from end to end...that is the keel structure. The structural frame of the ship is built up with the keel structure as the central member and is composed of longitudinal and transverse members that for a framework over which the plated is riveted (or welded). The strength of the hull girder lies in the rigidity of this framework, coupled with its "skin."

The keel itself is generally a heavy I-beam or T-bar. The strength of the hull girder is not dependent solely on that one component. The hull girder's strength depends upon a uniform and continuous structure. When I say the hull girder failed, I mean that the entire framework, keel structure included, suffered a discontinuity of some sort that allowed the concentration of stresses to occur in and propogate through adjacent members. A failure in the shell plating could begin a general collapse of the hull girder, just as easily as a fracture in any of the key longitudinal members, including the keel.

As a matter of fact, that's exactly what I believe happened. I believe that it was a near-simultaneous failure in the both the shell plating and a few of the key longitudinal members along the bottom of the hull that caused a bending moment that steadily increased as progressive flooding increased the loads on the structure. The bending moment moved aft as the bow slowly flooded, increasing all the while. When the bending moment found a portion of the hull girder with several discontinuities in the structure (open machinery spaces, large public spaces, staircases, etc.), the vertical shear stresses overwhelmed the rigidity of the structure, causing a catastrophic collpase. The keel structure was partially compromised during that collapse but did not completely fail, testifying to its individual strength. But, as I described, the keel was but part of the overall structure and would eventually fail when it lost the supporting strength of the framework of which it was a part.

Keep in mind that the angle of sinking may have no relation to the fracturing of the structure. A ship has loads acting upon it at times. The USS Schenectedy actually broke in half while tied up to the pier in January 1943. The steel was made brittle by cold temperature, but even so, static loading was what caused the hull girder to fracture.

By the way, increased brittleness in steel is not solely a result of cold temperatures. Some steel can exhibit brittle behaviour when a sudden impact load is applied, regardless of temperature, even if that same steel had shown ductility when loaded slowly. I don't believe this scenario was tested with samples brought up from the wreck. Too many people have a vested interest in seeing the cold blamed for the failure of the steel.

So, if you can visualise the skin and decks breaking, you can visualise the keel breaking. Computer simulations have provided probable angles for the break, but none have been proven. I therefore can't tell you what happened in exact units. I can only tell you what could not have happened.

Parks

P.S. A good portion of my explanation above is lifted from my old Naval Architecture textbooks and notes, which I thankfully kept. I wanted to ensure that I remembered my education correctly and not just give an interpretation based on memory.

 

[Erik Wood]

Great post Parks.

 

[Stephen Stanger]

YeessssH! I say so too! Cheers Parks!

 

[Stephen Stanger]

So is it safe to say that any of the animated sinking videos are inaccurate?
Cos all of them show the bow section pointing straight down before seperating then sinking down diagonally.

 

[Parks Stephenson]

I haven't seen any animation of the sinking that I would sign up to. A real ship does not need to take on an extreme trim in order to tear itself apart. From a CGI perspective, it might actually look quite anticlimatic, unless it were exaggerated a bit.

In the other thread, I mentioned that the production company making "Raise the Titanic!" commissioned my Naval Architecture professor to come up with a technically plausible scenario for raising the ship. The result was that our final report was completely disregarded by the filmmakers. Why? Because we had the ship brought up gradually, on an even keel, not even breaking the surface of the water until it had been towed to shallow water. That wasn't dramatic enough for the producers, who had visions of the bow shooting up out of the ocean depths. In the end, the producers went with the cinematically-appealing shot. All that work for nothing....well, almost. They paid for one heck of a summer academic project. And my copy of the report makes for an interesting and unique addition to my Titanic library.

Parks

 

[Haowei Shi]

I did some reserch.The Titanic break at 0218.

Haowei
FULL SPEED AHEAD