People trapped belowdecks?


Arun Vajpey

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Since the Lusitania lost power early after the attack thus plunging the unexposed interior spaces into darkness, I imagine many passengers and crew were caught out and unable to get up to the open decks before the ship sank. Since the ship had so many bulkheads including a longitudinal one and did not break-up during the final plunge, there must have been some air pockets in certain areas, particularly port aft ones. Could people have been alive and conscious in such areas even after the ship sank below the surface? If so, how long could they have lasted?
 

Charles

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I'm not sure, but Elsie Hook recalled going down to D-Deck when the torpedo struck, and headed back up immediately. It seems that the passengers in the dining saloon were shocked, and nobody really wanted to move for a minute.others seemed to beat them to the stairwell, and trapped them for at least 3-5 minutes, and the fact that they had to use their promenade to reach the boat deck probably hindered it more. One stewardess however recalls the promenade empty by the time she left (or at least her side)
 
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I hope this is accurate. I found on a website that at 93 meters below the surface of the water the pressure is 9.3 kilograms per square centimeter. That is all I know right now. I couldn't find the depth where an air pocket would implode. I will try and find it.
 
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Doug Criner

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"I couldn't find the depth where an air pocket would implode."

I don't there is such a thing as an air pocket imploding. Can you explain?
 

Athlen

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Below the surface, the air pressure in a "pocket" will be equal to the pressure exerted by the water. According to this site, water pressure increases by 1 atmosphere for every 33 feet, or 10 metres, of depth. (That is, water pressure at the surface is 14.5 pounds per square inch, the same as air pressure, and at 33 feet of depth the water pressure is 29 psi.) This means, roughly, that the volume of an air pocket will be reduced by half for every 33 feet of depth... so it will be 1/4 the original volume at 66 feet and 1/8 the original volume at 99 feet. Note that at some point the pocket will either have sufficient pressure to burst whatever is containing it, or it will dissolve into the water (this is not a phenomenon that we experience in the everyday world).

I'm not sure at all whether it would be possible to breathe the compressed air, and I think it's fair to say that the air pocket would be useless by the time the wreck sank to 100 feet. If not a hundred feet, then 200 feet (1/128 original volume). Lusitania sank in 305 feet of water.
 
Aug 2, 2017
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This discussion concerning the trapped air inside the Lusitania is both valid and relevant to a similar discussion regarding the Titanic. In both cases the knowledge of how trapped pockets of air dramatically lose volume when compressed. When an air pocket is pulled down 100 feet, according to the figures it would only be 1/8 of its original volume. These calculations indicate that extreme pressure forces within the hull, currently thought to be a contributing factor to Titanic's breakup at or near the surface, in actuality reveal that any such forces are short lived. For instance, a 1,000 cubic foot pocket of trapped air, once pulled down to a depth of 100 feet would only displace 125 cubic feet. So as the vessel sinks lower, the air trapped within it has approximately the same upward force, 62,430 lb. but concentrated in a smaller area. This may seem like enough concentrated force to rip steel compartments apart, however what about the weight of the water that has leaked into the ship and is pushing back in equal and opposite directions? Isn't the weight of the water on the other side pushing back equally and thus negating the forces of the trapped air?

It you consider the entire volume of the Titanic to be equal to her 52,000 Ton displacement, this works out to be 1.66 million cubic feet of air. Big deal! If the ship is sinking, and only one half of it is filled with air, then there is an "air bubble" trapped and pulling upwards with 26,000 Tons of force. Actually, this force is reduced by appx. 15% because of water buoyancy, leaving us with 22,100 Tons pulling downward.

How much steel did the Titanic have in cross section to resist this downward force? If we take Titanic’s 9 decks at ½” thick plus the two bottom 1” bilge decks, this represents an area of 92ft x12 in/ft. x 6 ½” total cross-sectional steel thickness, which equates to 7,176 sq. inches of steel. How much stress is on the steel: 22,100 tons/7176 in2 = 3.1 tons per sq. in. or 6,160 lb. per sq. inch.

How much force does it take to pull steel apart in tension? Laboratory testing of an actual piece of Titanic taken from the wreck yielded a value of 64,000 psi. This means, that in a worst-case scenario, the stresses imposed on the steel decks s of the Titanic would have been only 11.2% of the rated strength of the steel, and I have not added in the sides nor the structural beams beneath the floor nor the 18” bilge keels on either side nor the 3” x 3” steel keel along the bottom. Therefore, I have yet to see any kind of valid explanation of what caused this steel ship to separate into individual pieces.
 

Jim Currie

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Below the surface, the air pressure in a "pocket" will be equal to the pressure exerted by the water. According to this site, water pressure increases by 1 atmosphere for every 33 feet, or 10 metres, of depth. (That is, water pressure at the surface is 14.5 pounds per square inch, the same as air pressure, and at 33 feet of depth the water pressure is 29 psi.) This means, roughly, that the volume of an air pocket will be reduced by half for every 33 feet of depth... so it will be 1/4 the original volume at 66 feet and 1/8 the original volume at 99 feet. Note that at some point the pocket will either have sufficient pressure to burst whatever is containing it, or it will dissolve into the water (this is not a phenomenon that we experience in the everyday world).

I'm not sure at all whether it would be possible to breathe the compressed air, and I think it's fair to say that the air pocket would be useless by the time the wreck sank to 100 feet. If not a hundred feet, then 200 feet (1/128 original volume). Lusitania sank in 305 feet of water.
A cubic foot of salt water weighs about 64 lbs...29k gramms. At 1 ft depth, the pressure is 64 lb/cu.ft. At 2 feet depth it is 128 lb.cu.ft. It increases by 64 lb/cu ft for every foot of depth. An air-filled compartment which is sealed will eventually rupture when the pressure exceeds the strength of surrounding structure. Then, the air in the compartment which will be at surface pressure will escape in the form of bubbles.
 
Aug 2, 2017
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Folks, I guess this is the end. The air bubbles ripping out through the steel is the last and final word. Just one thing though: there have been at least three very informative posts between this post and my first that have been removed by the administrator. So neither this thread, nor this entire blog, is an encyclopedia of science but rather a dollar store of worthless trivia not yet edited out. What a joke guys! This from full grown men?

At least now I know why there are no alternate theories as to what ripped the Titanic into completely-separated pieces; there are! They've been edited out by the administration. Good bye.
 

Mark Baber

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Moderator's note: Nothing has been "edited out" of this discussion or any related discussion by "the administration" of this message board.
 
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>>At least now I know why there are no alternate theories as to what ripped the Titanic into completely-separated pieces; there are!<<

Of course there are other or alternative theories as HOW it happened but that's just haggling over the details. Most of them have been either refuted or revised in the light of new information. I've been watching discussions like this for years! There's really no question as to WHY it happened and it was because the bending loads on the hull girder were way in excess of anything it could possibly survive. It really isn't rocket science.

>>They've been edited out by the administration.<<

Oh piffle! Maybe you posted something in a different thread by mistake.
 
Aug 2, 2017
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What happened to the post with the drawing composed by the New York City Technical College of Marine Forensics. I posted it here myself, and it was up for a few moments. Then it and two posts above it disappeared. Of course I copied it, so I will post it again, let's see what happens.

"September 6, 2017

It is a pleasure to make your acquaintance. I greatly enjoyed your book.

I also spent some time trying to break steel toys. Caused me to write a book about steel "breaking".

Also spent some time thinking about all of that hull" out of the water" when the ship had supposedly been filling with water for 160 minutes, give or take. In your book you stated that 3rd Class people were still milling about, an hour, two hours (I forget). But it was as if nothing had happened. This is where I began to see some light. This was a key piece of information for me to put my version of the story together. My version is: The ship couldn't have had that much water in it and people not know it. Plus, if they knew it, they wouldn't be calm.
new york college drawing.jpg


How did 1/3 of the hull come out of the water when the ship was already more than half filled with water? But, honestly, this is all a mute point, since the New York City Technical College, Marine Forensics Division, has revised the high angle break theory to this: Low Angle Break Theory-Bow Drags the Stern Down. This is the fourth theory now.


Cheers! The search for the truth never stops.
 

Rob Lawes

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I'm sorry but you've completely lost me. What is your point regarding the break up? Are you saying it didn't happen due to an over stressed hull or are you saying it happened in the way shown in your diagram above?

I'm not sure why your getting your shorts in a knot. I don't think anyone has fully grasped the point you're trying to make.
 

Jim Currie

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Folks, I guess this is the end. The air bubbles ripping out through the steel is the last and final word. Just one thing though: there have been at least three very informative posts between this post and my first that have been removed by the administrator. So neither this thread, nor this entire blog, is an encyclopedia of science but rather a dollar store of worthless trivia not yet edited out. What a joke guys! This from full grown men?
At least now I know why there are no alternate theories as to what ripped the Titanic into completely-separated pieces; there are! They've been edited out by the administration. Good bye.
I presume you are referring to my last post, Kenneth? If so, I suggest you read it in full. I draw your attention to the bit where I write: " An air-filled compartment which is sealed will eventually rupture when the pressure exceeds the strength of surrounding structure". I presumed wrongly that since I was previously writing about water pressure, you understood that the pressure I was referring to was the pressure of the water at depth. Think submarine. I take umbrage at your observation: "neither this thread, nor this entire blog, is an encyclopedia of science but rather a dollar store of worthless trivia not yet edited out. What a joke guys! This from full grown men?"

Since you have re posted your sketch of the break-up: allow me to comment. The authors might have been at a marine College but they didn't know very much about the construction of a ship like Titanic.
For a start-off, there was no such thing as a double plate as shown in black. In fact, that area was known as the sheer strake and extended at weather deck level from the bow to stern and was connected on each side to the stern post. It is one of the two main longitudinal strength members of a ship. Titanic's keel was the other main longitudinal strength member. It was what is known as a vertical plate keel. It too extended from bow to stern. See here:
Titanic's keel.jpg
It was 6 feet or so deep forward of Frame No.-28. It increased in depth in way of the main Engine Room bed plates then was reduced back to 6 feet at Frame No. -58.....a distance of 90 feet. The break probably initiated in the area of Frame No. -28 forward of the main engine room but directly under the large, vertical void space which rose uninterrupted to the boat deck.
I do not think it was possible for the double bottom part in the way shown in your sketch. I believe that the two sections of DB seen on the sea floor, are the top and bottom sections of the DB tank area between Frames -30 and - WT bulkhead "J". I believe the keel parted in one length...from forward of the engine room to WT bulkhead "J". That bulkhead was a transverse strength member so would connect to the top and bottom of the keel.
By the way, I spent much of my life forensically analysing marine accidents for Lloyds Underwriters so perhaps I may be excused from your list of incompetents?
 
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