Did only 2 ft doom the Titanic?

[Steven Christian]

It is very interesting and you might want to read it alongside Chapter 6 of Sam's book (A Centennial Reappraisal). IMO, the Stettler-Thomas article is technically very detailed but Sam's analysis is more reader friendly to the likes of me from other fields. The Stettler-Thomas article can be a bit confusing about the bending stress level on the keel and how it led to the break-up; this is where Sam explains it better.

At about 02:15am, the bow was down by about 10-degrees with the Crow's Nest just touching the sea and water coming over the wheelhouse. It also coincided with the time when the bending force on the keel was close to its maximum (see graph on p119); it was also at that point that Sam calculates that the Titanic suddenly lost its longitudinal stability and started to tip over, dramatically increasing the rate of dipping of the bow. The resultant sudden displacement of a very large volume of water was what many survivors described as a "wave" that washed sternwards.

Thus, Sam has demonstrated that the bending force on the keel reached its maximum at about 11-degrees trim and very likely it and the deck plates started to fail at that point. But with so many decks and the keel itself forming part of the whole unit, the ship would not have simply 'snapped' in two. Even as the various levels were failing, the bow continued sinking rapidly because of the reasons mentioned above; as result of that the stern continued to rise and likely reached an angle of around 23 to 24 degrees when the full, catastrophic break-up, as seen and reported by some survivors, occurred - likely at about 02:18am.

I would bet money that Mr. Halpern gives an accurate and more lucent description as to what happened from reading his other stuff. As to the paper above I'm just saying that I'm reserving my judgement on it until I can go thru it more when I the time to delve into more deeply. When I read things like: "required working with the software vendor (DRS Defense Solutions) to effect modifications to the
software to attain the correct results." I have to take a step back and see if I can understand what they mean by that. The reason I'm like that is because I had to deal a lot with certain parties that wanted data manipulated to get the readings they wanted over my career. But I still liked reading thru it. It re-raised some questions on a more simple level that I wondered about before. Cheers.

 

[yotsuya]

That's certainly a very interesting diagram and graph. I downloaded this article from ET https://www.encyclopedia-titanica.org/community/attachments/study-titanic-pdf.39309/ and am going to read it slowly. Looks like something right up Sam Halpern's expertise and it would be nice if he would comment on both the article and the graph.

That is a good article, but it makes a few false assumptions. I see it is focusing on the aft expansion joint. The wreckage doesn't support that being the point of failure. Something changed at 2:15 to hasten the sinking. At that point it has taken 2 hours and 35 minutes for the bow to go down 10 degrees. How does that increase by 13 degrees in 3 minutes? The article makes a telling admission - it does not take into account any points of weak metal or rivets. It also doesn't take into account any twisting stresses. I don't think the scenario this article is based on is correct. I don't think it fits survivor accounts or the wreckage. I think the ship broke at a shallower angle and in stages.

 

[Arun Vajpey]

Something changed at 2:15 to hasten the sinking. At that point it has taken 2 hours and 35 minutes for the bow to go down 10 degrees. How does that increase by 13 degrees in 3 minutes?

Something - two things in fact - did change at around 02:15am that dramatically altered the dynamics of the sinking process and led to what we now call the final plunge. According to Sam Halpern, at around that time, the bow had dipped so that the ship had trimmed to 10-degrees; by his graph on p119 of his book, that was very close to the maximal bending stress on the keel. But whether by coincidence or direct relation (loss of buoyancy), that was also the point where there was so much water on top of the sinking bow that the Titanic suddenly lost its longitudinal stability and started literally to 'tip over'. That also suddenly increased the rate of sinking of the bow and consequently rising of the stern even though the keel and deck plates were already failing due to the bending forces. As I have understood it, the break-up process lasted between 2 and 3 minutes and the final catastrophic separation was the culmination of actions of those opposing forces.

 

[Samuel Halpern]

My first impression is that its a very technical analysis that concludes with this is "our best guess".

Any analysis, no matter how detailed or thorough it may be, is only as good as are the assumptions and data that go into it. There is a lot of guesswork, and that tends to be overlooked by many. The authors of that article were careful enough to point that out.

 

[Samuel Halpern]

Sam's analysis is more reader friendly to the likes of me from other fields.

Thank you Arun for the kind words. As some very famous physicist once said, if you can't explain something in relatively simple terms, then you yourself don't really understand it.

 

[Arun Vajpey]

Sam, there is something about the final plunge that I want to clarify. As you said, by around 02:15am the Titanic had trimmed down to about 10-degrees, which was very close (in the graph) to maximal bending stress on the keel. Then you explained that in the next 1 or 2 minutes the ship lost its longitudinal stability and started to literally tip over - let us say 90 seconds for the sake of discussion. During those 90 minutes the keel went through an almost continuous phase of near-maximum to maximum stress, right? But also during those 90 seconds the bow continued to dip and the stern rose, finally leading to the break-up.

My question is about the physics involved which I have limited knowledge. The fact that those 2 forces - the bending force on the keel due to the stern being unsupported and the sudden loss of buoyancy of the bow - occurred within such a short space of time; was it related specifically to the anatomy of the Titanic?

 

[yotsuya]

I'm going to have to disagree with the ship rising to a high angle. I think Roger Long and Roy Mengot nailed it with a low angle for the breakup. I disagree with them slightly on the mechanics of the breakup, but not the angle. Roger Long had a cruicial observation that a top down break up would leave clean edges and what we see in mangled. He proposed a top down break with the ship counter bending and crushing the upper structure. He is right about the need to account for that mangling of the upper structure. Roy pinged he bottom breaking first, but I think Cameron is right that the double bottom held on and pulled the stern down. And I don't think the ship had as much water in it as some simulations assume.

 

[Samuel Halpern]

I don't think there is anything that unique to Titanic. Any vessel where the stern get pulled up by the bow being flooded would undergo high stresses in the hull girder as the stern gets lifted higher out of the water until a maximum stress angle is reached. Whether or not the hull would break depends on the strength of the steel that was used. The ship did not sink because the hull broke; the hull broke because the ship was in the process of sinking.

 

[Samuel Halpern]

I'm going to have to disagree with the ship rising to a high angle.

I agree with you, but what one must ask, what is considered a high angle?

 

[Michael H. Standart]

Ship's carpenters have a long history of enacting repairs on ship. The change from wood to metal hulls changed things a bit, but I'm sure many of the same procedures remained the same. For Titanic, there was just too much damage. There were some valiant saves in the age of wood and sail by ship's carpenters.

On smaller hulls. The change from wood to metal and the vast differences in size changed a LOT, not a just a little.

It seems to me that you're still trying to posit an understanding of large-scale damage control along with resources which did not in fact exist in 1912. The principles are fundamentally the same, but the resources just weren't there. NOBODY had collision mats on any of the liners and you see nothing of the kind even today.

There are a lot of reasons it wouldn't have worked out then, not the least of which was that they didn't know exactly where the breeches were. That's kinda important and you can't plug or patch a hole if you can't even find it.
They didn't have divers to help find anything or lights that would work underwater, nor did they have divers suiting which would protect a diver in 28-degree water.

Actually, they had no diving equipment aboard at all.

 

[Steven Christian]

Any analysis, no matter how detailed or thorough it may be, is only as good as are the assumptions and data that go into it. There is a lot of guesswork, and that tends to be overlooked by many. The authors of that article were careful enough to point that out.

Yes. I stated that in an earlier post.

 

[Arun Vajpey]

I'm going to have to disagree with the ship rising to a high angle.

I agree with you, but what one must ask, what is considered a high angle?

I have always accepted Sam's excellent paper "Why The Low Angle Break?" with its carefully detailed analysis and that telling "Bending Moment vs Angle of Trim" graph. Sam clearly demonstrates how the bending force on the keel rose sharply as the bow trimmed down, till reaching a maximum somewhere between 11 & 12 degrees at about 02:16am. It was about a minute after that the ship lost its longitudinal stability and the bow plunged sharply, generating the wave.

That said, most survivor accounts suggest that the stern was higher when the break-up as those few who saw it occurred and it was more likely around 02:18am. I believe that this apparent discrepancy is due to what actually constituted the "break" as we know it. The Titanic was made up of a keel, double bottom and several deck levels, all of which had to come apart visibly to justify statements of those survivors who saw the ship break in two. Although a catastrophic event, I believe the break-up extended over a couple of minutes at least that started when the Titanic was at a relatively low angle of between 11 and 12 degrees but being subject to the peak of the bending force. During those 2 minutes the bow continued to dip and the stern rose, even though the two "parts" were steadily coming apart. It is quite possible that the stern reached an angle of 23 to 24 degrees before the final separation occurred and that would have been what most survivors who reported the break-up would have noticed.

 

[PeterChappell]

There are a lot of reasons it wouldn't have worked out then, not the least of which was that they didn't know exactly where the breeches were. That's kinda important and you can't plug or patch a hole if you can't even find it.

I agree that the positions of the breaches in the forward compartments were unknown which made it impossible to cover these compartments without covering a substantial part of the ships hull which was impractical.

However, a substantial part of the damage may have been caused by a single spur of the iceberg at a similar height, stretching from BR5 intermittently through much of BR6. The next breach in the adjacent holds may have been slightly higher. Is that just down to where the plates join? The workers in BR6 would have noticed where the water came in, not least due to the rivets fracturing, and that coincides with the height of the visible breach in Boiler room 5. From that information, perhaps Andrews would have be able to identify some of the plates which had opened up from his drawings and thus determine the height?

Even with the right equipment ,I doubt if it would have been possible to cover much of this before BR6 was filled and all the flooded compartments were joined, so it's probably of academic interest only.

 

[Arun Vajpey]

The workers in BR6 would have noticed where the water came in

They might have noticed the general area from where the water was coming in, but I doubt if most of them would have had time to see the actual breaches before the (the damaged areas) became submerged. Putting ourselves in the positions of the crew of BR6, the alarm bells would have been their first warning that anything was wrong. Then they would have been busy shutting dampers and other tasks before the actual impact. A few might have seen the first jets of water gush-in but BR6 flooded so rapidly that the force of the water would have made access very difficult before the breaches went underwater.

 

[PeterChappell]

They might have noticed the general area from where the water was coming in, but I doubt if most of them would have had time to see the actual breaches before the (the damaged areas) became submerged. Putting ourselves in the positions of the crew of BR6, the alarm bells would have been their first warning that anything was wrong. Then they would have been busy shutting dampers and other tasks before the actual impact. A few might have seen the first jets of water gush-in but BR6 flooded so rapidly that the force of the water would have made access very difficult before the breaches went underwater.

Harland and Wolff used larger sized plates to reduce the amount of butts and overlaps. I think they were 6 feet high and 30 feet long. There's quite a difference between water entering at ones feet, at head height, and 6ft over the head. Wouldn't this localise the height of the breach, assuming Andrews had brought the drawings?