Hypothetical Question


Dec 3, 2005
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First off, I'm new here and glad to finally be aboard. Secondly, I have this hypothesis. It seems to be general consensus that Titanic took on an appreciable list to port late in the sinking. I'm tempted to wonder if she hadn't have broken in two, what are the chances she would have lost stability and rolled over to port when she reached neutral buoyancy. Of course, I'm remembering sinkings like the Eastern Challenger or the Spiegel Grove here. What do you all think?
 
Dec 2, 2000
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>>What do you all think?<<

Hard to tell. The Titanic was odd man out in terms of casualties in that she remained on a more of less even keel throughout most of the sinking. There are a lot of factors which play into how a ship sinks and they're not as well understood, even today, as we wish they were.
 
Dec 4, 2000
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Peter-- A fantastic first post. You have touched on something that I'm currently trying to research. It seems to me that by the time the bridge went under Titanic had lost stability and was going to port in a "death roll." I see the breakup as the factor which put an end to that roll.

-- David G. Brown
 
Dec 2, 2000
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Further to just how unpredictable sinkings can be, watch the vidio of the former USS Oriskany going down at http://cbs11tv.com/watercooler/watercooler_story_137164650.html

Keep in mind that this whole event was carefully planned out with explosive charges placed and with cuts in the hull and bulkheads which were intended to sink the ship on a more or less even keel. I noticed that during the sinking, the ship had rolled sharply to starboard and also that she sank in less then 35 minutes. The prediction was that she would take up to 5 hours to go down. This just goes to show that even in a controlled event, there's always room for surprises. Titanic was very much an uncontrolled event.

We have a lot to learn about the dynamics of how ships sink.
 
Dec 3, 2005
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I'm glad to know that my idea wasn't completely insane. To my mind, the transverse bulkheads would only encourage a cascade effect inside the ship and a rollover if she were very full of water. I'd like to know how it would have affected the sinking if she had longitudinal bulkheads as well. Probably would have listed heavily to starboard, but I wonder how much longer she could have floated. And it's funny Michael, I saw that video online about an hour before you posted it here. This one was in real time however and showed only the first few minutes of the sinking. Probably the most unpredictable sinking I've seen was one of a large passenger boat whose name I only wish I knew. She went down by the head until her entire bow was underwater and her stern was rising noticeably. All of the sudden she changed her mind, swung back level in the water, stuck her bow up and went under steeply by the stern. Rather indecisive, eh?
 
Mar 22, 2003
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Peter. The list to port on the Titanic was never very severe. At most it was only about 10 degrees, or half the list it took to starboard at the very beginning. It certainly did not prevent the launching of Collapsible C on the port side at 2 AM despite some difficulty of getting hung up by rivets as it was lowered. The list to port can be estimated based on the reported gap (~2.5 ft) between the edge of a lifeboat No. 10 and the rail on the boat deck within the last 40 minutes before the ship went down. Just prior to the breakup, the longitudinal trim had attained a down angle of about 10-11 degrees. Up until that point the ship was obviously stable with slowly changing trim and list angles. It looks like the ship would have lost longitudinal stability before loosing transverse stability if it hadn't broken first. The work of Hackett and Bedford show that if the WTDs could have been kept open the ship would have taken on much more severe angles of list and would have capsized before going down in a much shorter time period. An interesting academic observation. It should be pointed out that even if some of the WTDs were left opened in unflooded compartments, they would automatically close once water entered those compartments because of a float mechanism that would have released the clutch that held them open.
 

Roy Mengot

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May 16, 2006
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I had a chance to talk to Chris Hackett when I was at H&W in the late 90's. All the work in the B&H paper shows that at the time Titanic's stability (GM/GZ curves) go negation. The ship will tip up and fall by the nose. What's not in the paper is another scenario they ran as they played a few 'what if' games.

Titanic goes unstable about the time everything forward of #4 boiler room is flooded, and #4 boiler room is about half full. The ship will tip up (and did). If, at that point, you move half of the water in BR #4 to BR #3, the ship will roll. He didn't say which way as they largely ignored the slight list throughout the simulations.

Regards
Roy Mengot
 
Dec 3, 2005
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Was it really 20 degrees to starboard, Samuel? I always thought it was more like 3-5. I would expect less skepticism among the passengers if that were the case. That's Andrea Doria land right there. As for the capsizing if the watertight doors were open, that's a result of the water spreading aft along the starboard side inside of having to trickle over to port, or am I completely misinterpreting it?
 
Dec 2, 2000
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>>I'm glad to know that my idea wasn't completely insane.<<

It wasn't insane at all.

>> To my mind, the transverse bulkheads would only encourage a cascade effect inside the ship and a rollover if she were very full of water. <<

Actually it tends to be the other way. Transverse bulkheads allow water to flow from one side to the other and this makes it a lot more likely that the ship will stay on a more or less even keel throughout the event. The presence of longitudinal bulkheads tend to confine water to one side and promote a rollover if the damage is severe enough. This is the reason Harland & Wolff disliked them and preferred transverse bulkheads.

Of course, the devil is always in the details and there are a lot of things that can throw a monkey wrench into the works such as

•Cargo shifting because of poor restraining measures or simply because the nature of the accident rendered any sort of restraints irrelevant.
•Non structural bulkheads and doors which tend to restrain the flow of water even if they can't stop it.
•Vents, wireways, as well as,
•Plumbing waste/drainage systems through which water can back up and flood the entire ship. (This is what happened to the Oceanos when the sea chest ruptured and the DWV system wasn't properly blocked off.)
•Free surface action in large spaces causing a rollover, and
•Watertight decks which are damaged high up and raise the centre of gravity, also promoting a rollover.

>>As for the capsizing if the watertight doors were open, that's a result of the water spreading aft along the starboard side inside of having to trickle over to port, or am I completely misinterpreting it?<<

That's free surface action doing the dirty work there. That is the tendency of water to shift from one side to another if there's nothing to restrain it, and for the condition to make itself worse over time. This phenomenon is the reason the tankers have anti-surge baffles built into each of the tanks.

>>And it's funny Michael, I saw that video online about an hour before you posted it here. This one was in real time however and showed only the first few minutes of the sinking.<<

I'd love to see a time lapse vidio of the whole thing as I noticed in one of the still photos on the Navy Newsstand site that the Oriskany first shifted to port before tipiing up and rolling over to starboard. For all that this was as meticulously planned out as it was, the unpredictable was well at work here.
 
Dec 3, 2005
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That's alright, Sam. I'm still tempted to picture her rolling over, though, maybe just because it seems unnatural for a ship to settle evenly like that. Didn't her stern section fall onto it's side before it tipped up? I'd like to look into the mathematics of those other sinkings Eastern Challenger and Spiegel Grove and see how they compare to Titanic.
 
Mar 22, 2003
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Too many uncertainties I'm afraid to accurately predict what will happen. I've seen pictures of torpedoed ships with broken backs sinking with bow and stern sections pointing upward without developing any perceivable list. I've also seen other pictures where the ship first rolls over onto its side before going down by the head or stern first. It all depends on flooding patterns and the changes to GZ curves.
 
Dec 3, 2005
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Well, I'm still rather an amateur with ship physics. The number of variables involved doesn't really help either. Speaking of stability, though, does the general idea of metacentric height/center of buoyancy/center of gravity still apply to longitudinal stability?
 
Dec 2, 2000
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>>The number of variables involved doesn't really help either.<<

You're right. They don't, and there are a lot more of them then what I placed on my list above. We've been discussing them one way or another for years. You might find it useful to parse some of the threads in this folder to see where we've been. Suffice to say that one way or another, we're all on a learning curve here.
 
Dec 4, 2000
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Someone asked about Roy Mengot. He is a long-time Titanic researcher and the builder of the most famous model of the wreck. (Ask to see the video.) Roy is a member of the SNAME forensic committee, an engineer, and an all-round good fellow. Those who know Roy trust his research and listen to his opinions.

But, you gotta see the video.

-- David G. Brown
 
Dec 3, 2005
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I've seen Roy's model of the wreck. I want that thing as a centerpiece of my dining table. Seriously though, you did an amazing job on that thing Roy, especially given the clarity of a lot of those wreck photographs.
 
Dec 4, 2000
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Sam-- I knew it was a rhetorical question, but it gave me a chance to mention "The Video." Those who have seen it know that Roy's video of his model building activities is...ah, memorable. I'm still not sure about the cowboy business, though.

-- David G. Brown
 

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