What caused the damage to the stern?

A

Alicia Coors

Guest
The view of certain credentialed naval architects is that the stern section exploded after reaching a depth of about 300 feet. In their view, the compressed air inside the wreck violently forced its way out, splaying the sides asunder and rolling back the poop deck like a sardine can.

I think this is impossible, because the pressure inside would never exceed ambient. Does anyone know how these mature, educated engineers might explain it? Failing that, can anyone suggest how the stern got wrecked?
 
Jan 21, 2003
271
1
146
Hey Alicia
There was alot of air trapped in the stern section and as the pressure increased it began compressing the hull til it literally exploded from its compressed air. Also i think it had a hard hit on the bottom which couldnt have helped.
 
Dec 2, 2000
58,584
376
283
Easley South Carolina
>>I think this is impossible, because the pressure inside would never exceed ambient. <<

Okaaaaay....since this seems a valid question, perhaps somebody who can find something with the science to back up or refute these positions can do so.
 
Dec 4, 2000
3,226
480
213
The commonly-accepted theory is that spaces such as the refrigerated storage rooms did not flood passively, but retained air. As the stern sank, the walls and decks which made up these enclosed spaces were forced to sustain the increasing water pressure. At some point (different for each large space) the theory is that they imploded (collapsed explosively inward). An underwater implosion can be quite violent, as was illustrated by the Thresher disaster.

A number of survivors in lifeboats reported hearing dull "booms" or sounds like large artillery at a distance after the stern disappeared. These sounds are attributed to the implosions.

There is controversy over whether the air inside the imploded spaces would have rushed out in a near explosive fashion. Or, some suggest it would have come out as compressed "bubbles" and only expanded as it floated upward outside the confines of the stern. One thing certain, air expelled from an implosion would have been compressed to a fraction of its sea level volume by the pressure of the deep.

Either way, it is probable that air trapped beneath the poop deck would have created buoyancy sufficient to have started pulling that deck upward. Water pressure from the descent probably finished the job of "peeling" that deck back like the lid of a sardine can.

All of this is speculation as it happened out of human sight. What we see are the results. The only firm conclusion is that sinking is not always a quiet event, but can be one full of violence for the ship involved.

--David G. Brown
 
Mar 22, 2003
5,253
684
273
Chicago, IL, USA
Upon collapse of an inclosed space, the air inside would have compressed to a fraction of its sea level volume and escaped as compressed bubbles. The violent compression of the air is what an implosion is all about. Think of it as an explosion run backward in time.
 
A

Alex McLean

Guest
David,
Can you tell me which passengers and crew heard these reports, and when they stated them (inquiry, personal reflections, etc.)
My best,
happy.gif

Alex
 

Paul Lee

Member
Aug 11, 2003
2,239
2
108
I think Frank Prentice heard dull thuds below him as he lay in the bottom of the lifeboat that rescued him.

By the way, does anyone think that the stern "flipped over", so that it was heading fan-tail downwards before it imploded? I ask because the poop deck is peeled in a fore-aft way, not from the aft forewards.

Cheers

Paul
--
http://www.paullee.com
 
A

Alicia Coors

Guest
It is obvious to me that the stern imploded (as the phrase "the pressure inside would never exceed ambient" in my initial post intended to imply). The hull girder may have been weakened by the differential pressure, but most of the damage was internal.

My question is: what could possibly explain why people with an engineering background would posit the stern being wrecked by explosion? Roy Cullimore went so far as to suggest that the poop deck was peeled back by compressed air rushing out of the 3rd class stairwell. I not only don't see how that would happen, but I don't see why he would think it could.

The idea that the shell plating was detached by the slipstream also seems unlikely. If water pressure alone could account for ripping the plates loose, they would be spread all over the seabed. But they aren't. They're either hanging from the hull by a thread or lying next to it. The following explanation for this arrangement might fly:

Owing to the high concentration of mass in the engine spaces (compared to the bow section), the stern section dropped much faster under the influence of gravity than the bow, hitting the bottom at considerably higher velocity than the 22 knots that the model bow did. The damage shown in Roy Mengot's model of the stern at http://home.flash.net/~rfm/STERN/stern.html is totally consistent with a sudden stop from a high speed. As the incompressible water inside looked for an outlet under the influence of the collapse, it both blew the sides out and produced a jet through the stairwell that tore the poop deck loose and folded it back.
 
Mar 22, 2003
5,253
684
273
Chicago, IL, USA
quote:

My question is: what could possibly explain why people with an engineering background would posit the stern being wrecked by explosion? Roy Cullimore went so far as to suggest that the poop deck was peeled back by compressed air rushing out of the 3rd class stairwell. I not only don't see how that would happen, but I don't see why he would think it could.
You would have to ask them. I agree with you. There would be no explosions in the stern section. Your explanation may be the answer to the observed damage.​
 
Dec 4, 2000
3,226
480
213
I have no problem accepting that the slipstream resulting from sinking could have "peeled" the poop deck back. In fact, that does appear to be what happened.

As to the air explosively coming up the third class stairway...well, i'm with Sam's view that the bubbles would be compressed and not expanding violently. They would, however, have gathered beneath the poop deck where they would have for a while provided buoyancy which may have helped lever the deck off.

As to who heard explosions, the answer is just about everyone who described the last moments remembered something that sounded like cannons or thuds. (Or, implosions?)

As to TV documentaries...what comes out on the screen may not be exactly what the contributors intended. The goal of entertainment TV is to attract sufficient number of viewers to "sell" to advertisers. Ads in American TV lingo are called "spots." During my days as a news producer we had a saying, "see spot run. Damned spot better run!" The term "run," of course meant that it got on the air as planned. The news was simply the stuff between spots.

So, keep in mind that anything on TV is first intended to entertain and draw an audience. If secondarily it enlightens, so much the better. But, truth and facts are not required in TV productions. I daresay there must be hundreds of "horror stories" about how scientific research was twisted by the documentary producers just to have a more exciting program.

-- David G. Brown
 
Dec 6, 2000
1,384
1
166
Alex - you can find some of the passenger & crew testimonies of what they saw and heard in my article here at ET - it's call "The Facts - What Did the Survivors See of the Breakup of the Titanic". I went thru all the testimony at both Inquiries, and excerpted what was said.
 
A

Alicia Coors

Guest
David,

I understand your remark about the trapped air providing a little buoyancy, but once that air was submerged by 99 feet, it would only occupy one-fourth of its sea level volume (assuming that everything that was going to implode had done so by then). That probably wouldn't provide enough buoyancy to lift very much.

But your slipstream analysis is probably spot on. If the hull was headed down fast enough to smash to bits on the bottom, there was undoubtedly enough flow across the well deck to peel up the poop.

I have no doubt that the witnesses were hearing things like the refrigerators imploding.

But I remain a little surprised that a marine engineer would suggest that the stern was wrecked by explosions (even for TV consumption).
 

Jeremy Lee

Member
Jun 12, 2003
1,374
1
106
>>But I remain a little surprised that a marine engineer would suggest that the stern was wrecked by explosions (even for TV consumption)<<

Obviously! There is nothing in the stern that would cause an explosion, at that time he probably mixed up the words explosion with implosion.....
 
Dec 4, 2000
3,226
480
213
A thought -- As the stern went down, air had to come out. Otherwise, it would have remained buoyant and might still be floating. That air was compressed by the sinking of the stern. How much? I don't know. However, motion pictures of ships sinking (mostly WW-II torpedo victims) that I have seen often have hatches blowing open and other signs of compressed air "exploding" outward. Could compressed air up the 3rd class stairway have damaged the poop deck? Maybe, or maybe not. But, the result would have been an increasing "blast" of air in that space.

As to what scientists say, they are human and sometimes toungle their tangs. I suggest that Alicia attempt to contact the people involved. I've had great success with polite e-mail inquiries.
 
Mar 22, 2003
5,253
684
273
Chicago, IL, USA
There is another possibility that could be considered for large spaces that would be subject to implosion. The three spaces between bulkheads M and O, and between the tank top and the Orlop deck, were separate watertight compartments. (These were the electric dynamo room [along with the 6 fresh water tanks] and the two shaft tunnel compartments.) The escapes from these spaces were watertight shafts that ran all the way up to D deck level. Assuming that the watertight doors on the tank top aft of bulkhead F were closed again later that night, before the ship broke up and took its final plunge, then these three spaces would have contained a relatively large volume of air. As the stern section went down, water flowing down through the escapes (the only means of access to these compartments) would have closed off these compartments preventing air from easily escaping out. Think of it as taking a closed jar with a small hole in its lid and pulling it under water quickly. If the stern section sank really fast after it went under, the water pressure could have exceeded the crush depth of the hull before enough air could bubble out of these spaces causing these sections to implode, one right after the other. (see attached diagram.)

86861.gif


Regarding the popping of hatches on sinking torpedoed ships, this is caused by a sealed compartment being ripped open to the sea from below. The internal compartment pressure would take on the pressure of the sea after the trapped air gets compressed. The pressure difference between the top of the compartment hatch and the pressure of the trapped air within the compartment (equal to the sea pressure from below) could be enough to blow the hatch covers.
 

Lee Gilliland

Member
Feb 14, 2003
511
0
146
"Obviously! There is nothing in the stern that would cause an explosion, at that time he probably mixed up the words explosion with implosion.....'

Did they even know the difference back then?
 
Mar 22, 2003
5,253
684
273
Chicago, IL, USA
"Back then" I assume you are referring to 1912? Yes, engineers in 1912 would know the difference between implosion and explosion. The average person, even today, may not have heard of implosions. Regardless, what people would have heard would have been described as "explosion," a term that most people were familiar with.

What Alicia is asking is something very different. She is asking why knowledgeable people today with an engineering background would suggest explosion rather than implosion? The suggestion, I believe, would come from the scene at the bottom of the Atlantic. It looks like something exploded in the stern section. The explanation for what one sees, however, needs to be thought out. For an explosion to occur, there has to be a greater internal pressure relative to the external pressure. Not the other way around, which would cause an implosion. If it was compressed air that exploded outward, where did that compressed air come from? How did it get trapped at a pressure greater than the surrounding pressure? And when did that explosion happen, near the surface or deep below? I am speculating that these experts that were interviewed may not have thought the problem through. It is OK to speculate, but any speculation needs to be based on plausible, well thought out assumptions. And this is what I believe Alicia is questioning.
 
K

Keith R E Hall

Guest
I have an image of the damage to the stern section but it is to large to upload so if you email me at hdollygrey@aol.com i will send it to you as an attachment. I also have the bow section and the bridge which shows the steering telemotor but the ships telegraphs are gone.
 
Dec 4, 2000
3,226
480
213
By chance, last night one of the airplane channels on cable TV ran a story about forensic investigations of two crashes involving the failure of the aft bulkhead of the pressurized cabin. One was a Japan Air Lines 747, the other plane a British prop-jet. In both cases, the pressurized air rushing out of the cabin through the ruptured bulkhead was forceful enough to "blow" apart the tail structure.

The analogy between the two aircraft and Titanic is not exact. For one thing, the aircraft were surrounded by thin, low pressure air, whereas the sinking stern was surrounded by dense water. However, the thought of air expanding with enough force to destroy an aircraft does bring to mind what we see in Titanic's stern on the bottom.

My thought is that we have not considered the pressure differential with depth. Some parts of the stern would have been 150 or more feet down, while the taffrail was still dry. Thus, air under the pressure of that depth would have been sought the surface by passing through whatever openings that were available...or, perhaps by making new openings as in the aircraft.

My thought..hunch, really..is that any damage done by air pressure would have been in areas still at or above the level of the sea and that the air under pressure was coming from tens if not a hundred feet down.

That said, I cannot think of any testimony where a survivor describes anything approaching an explosive rush of air. The closest I can come are the remarks in which the "booms" were attributed to boiler explosions. Anyone remember any better descriptions?

-- David G. Brown