Hydrodynamics and Suction


Status
Not open for further replies.
Sep 12, 2000
1,513
6
313
Dean and Michael, Thanks, you both are wonderful for taking time to help me understand. And the comments by Jack Theyer about the bobbing around is interesting as well. I understand better what the keel is and about how thick it would have been. It helps me to use my imagination,... but at times I really need help.
 
D

Dean Manning

Guest
Hi Michael and Maureen!

I just watched the video that I had mentioned above. Apparently, there were two separate finite element analysis done on the Titanic, one in 96', and the other in 98. The one done in 96' is the one that is on Gibbs and Cox's web page. The one done in in 98' was done by a different structural engineer, and reveals something that I had overlooked. On the stress analysis, the deckhouse around the second expansion joint are still colored red, indicating high stresses. But, the stresses down by the keel were only colored green. The implication from this is simple. The keel didn't suffer, at least when the stern was in the air, the same magnitude of stresses as the deckhouse did. The other implication is that the upper part of the ship broke in half first.

One other note. The 65,000lb/in^2 figure was quoted in the 98' analysis. I think the differences between the magnitudes of the stresses, both in location and magnitude are mostly likely due to additional data that wasn't available in 96'. I'll check my sources to see if this indeed the case.

bye!

-Dean
 
Sep 12, 2000
1,513
6
313
Bill DeSena is awefully quiet out there. Did the ship emergency test go well? Did he survive that terrible ordeal with all those young ladies? Did he ever get the stoweaways to board the lifeboats? Did he ever get any of his family members to buy into this whole thing in the first place? Did he sell the yacht to pay for interests in Michael's, Maureen's and Pat's real air captured from the ice berg scam...I mean...uh..oh what's the word....sale...deal of the century...yeah that's it? Does anybody know?
 
Sep 12, 2000
1,513
6
313
Hey there Dean.
I have another question. You were indicating the red and green variations...how does the third piece measure up in all of this? Okay, the bow section is in one place and was the one with the water. The stern section was the one with its....up in the air. I think what you are saying is that the pressure was not a bow versus stern issue it was a keel versus upper portion of the ship problem and that is where the pressure was greatest.

So, where did this third piece come from and at what point did it separate from the ship? Did it separate from the bow first or the stern first or did the ship immediately break into three parts...kinda like when you spread apart an orange slice/half...when the peel is made flat, the orange kinda breaks into little sections. Maybe bad analogy, but I am trying really hard to imagine what happened. Anybody?
Maureen.
 
Jul 9, 2000
58,662
872
563
Easley South Carolina
Hello Dean, and thanks for that peice on thefinite stress analysis. Now I have to get that vidio one way or the other.

It might be worth noting that the break happened at what would be the weakest part of the structure, as in the region of the 1st Class Dining Saloon.

Mo, the big problem with the part in the air was that it was supported by nothing more then thin air. For a structure designed to be supported by water, that's not a good thing.

Cordially,
Michael H. Standart
 
Sep 12, 2000
1,513
6
313
Michael,
Okay, so for example, if I have a ship model that is eight feet long and I fill the front third of it with water and the back third of it has heavy stuff likethe engines and there is just hollow space in the center, when I let go of it the center will snap breaking at the top not bottom because the way the stress is built up from the strain of trying to keep the bottom staying straight up...right?
Thanks so much! I think that I am starting to get a handle on some of this stuff. I also bought several books today. One is on ship handling.
Maureen.
 
D

Dean Manning

Guest
Wow Maureen, your getting into this awfully deep! I think your really starting to understand this because your starting to ask questions that we don't have answers for yet. However, I'll try to answer what I can. Here goes.

First the stresses in the hull and the color association. A little bit of background is required here. I've mentioned the term finite element analysis in several of my post here at ET, but I never really said what it was. A finite element analysis is a computer tool based on linear algebra that calculates complex loading situations and reveals the stresses on the structure with a square colored mesh. The colors in the mesh represent the stresses in the structure. In the case of the Titanic, a 3D computer model was created and the data about the flooding patterns as well as the ships buoyancy curves, steel strength and weight distribution were entered. The computer then calculated the stresses in the hull. As it turns out, the highest stresses occurred in the upper region of the ship, at the second expansion joint, which is just behind the third funnel. There is debate as to whether the stern and bow section broke completely apart at the surface. But, the computer model showed at the region of the keel and double bottom only moderate stresses. With the high stresses at the top, and only moderate stresses around the keel and underbottom, it seems highly probable that the Titanic split apart at the deckhouse first, and then worked it's way down almost to the bottom of the ship.

So how does the third piece measure up in all this? Well, the third piece was the only section of hull left that was holding the bow and stern together when the ship slipped under the surface.

The third piece came from the bottom of the ship. The best way I can think of explaining this to you is like this. Imagine a crack running down the side of the ship. Before it gets to the bottom, it splits into a "Y", forming two cracks. The same thing happens on both sides, and the two cracks that formed on each side go under the ship and meet at the keel.

After the ship left the surface, all that can be said for sure is that it broke into three pieces at relatively shallow depth (about 500ft or so). At exactly what depth, and whether all three pieces broke away from each other at the same time or different times is an issue that just hasn't been resolved yet.

While science has shed a lot of light on what's happened, it's never going to be able to gives us an exact description of what happened. There are just too many variables involved to pinpoint everything down to an exact sequence in which the breakup occurred. Having said that, most of the information here, and in fact, on this web site, is debatable. Michael had mentioned in one his posts above that he thinks the ship may have broke apart before completely leaving the surface. He could be right. Nothing is set in stone.

I hope this helps, at least a little. If you need clarification, please say something.

I wonder what happened to Bill as well. Maby the suction from his model pulled him, his daughter, her friends, and all the dolls down when it sank... ;) I'd like to hear about any further experiments that he's conducted.

-Dean
 
D

Dean Manning

Guest
hi Michael and Maureen!

Michael, I hope you enjoy the video. As far as I'm concerned, it's a pretty good documentary.

Your absolutely right about the weakest part of the deckhouse being at the breaking point. It's definitely a major point to consider.

Who knows if the model will break, Maureen. And if it does, who knows if it will break the whole way through. It was in Titanic's nature to break the way she did.

It's 3:00am, I'm going to bed.

-Dean
 
Jul 9, 2000
58,662
872
563
Easley South Carolina
Good Morning Mo...if you get up in the morning. Now that my shift has changed, I have to get used to living in sunlight again. I hope it's not as hard on me as it was on Count Dracula.

In regards the break, I'm impressed by the questions you're asking. They're good ones and some of the answers proposed are a matter of debate. I've seen it mooted that the break happened at the keel first. With the weight of the engines and boilers combined with wide open spaces such as the machinary rooms and the dining saloon, it's certainly possible that it happened that way.

But, as Dean explained, it's a very debatable proposition. That chunk of double bottom could well toss the monkey wrench in those works. Say, the break happening at the superstructure first, then the keel breaking in two places next. Or the keel could have snapped first, possibly in two places, and set everything else in motion. A nasty variation of the domino effect either way.

By the way, what titles are you buying? With the questions you're starting to ask, it sounds like some territory I need to explore further.

Cordially,
Michael H. Standart
 
Sep 12, 2000
1,513
6
313
Titles? "Sir" ...ummmm "Your Highness"....ummm let's see ...uh..... oh you mean book titles?

Not in any particular order are some of the titles that I had already owned are:
1) "Dear America - Voyage on the Great Titanic - the diary of Margaret Ann Brady - RMS Titanic 1912"
2) "Titanic - Colonel Archibald Gracie - A survivor's story"
3) "Titanic - Eyewitness Books"
4) "James Cameron's Titanic"
5) "The Last Days of the Titanic" by EE ODonnell
(I actually have three copies of this- don't ask)
6) "Titanic" by Leo Marriott
7) "Titanic-An Illustrated History" byLynch,MArschall and Ballard
8) "Titanic - lgeacy of the world's greatest ocean liner" by susan wels
9)"James Cameron's titanic - the poster book" (a treasured gift)
10)"Molly Brown Unraveling the Myth by Kristen Iversen/Muffet Brown
11) "The Story of The Titanic" Beesley, Gracie, Lightoller, Bride
12) "Titanic - fortune and fate" The MAriners Museum
13)Sinking of Titanic Eyewitness accounts - Mowbray
14) "Titanic - Destination Disaster- The Legends and the Reality" eaton/hass

Some of what I picked up yesterday were:
1) "Ken Marschall's Art of Titanic"
2) "Explorations-A life of Underwater Adventures" by ballard
3) Lost Liners by Ballard/archbold
4) The Annapolis Book of Seamanship by John Roumaniere (just so I can keep up with you guys out there!)
5) Checking on the Boat ( a non leather land lubbers guide to wriitng a boat log...just kidding) by Mystic Seaport

I also own some others but space is limited and no one really wants to know what is in my library.

I also own the Discovery channel amd A&E tapes on the Titanicas well.
I stopped and read an architect type of book as well, but it was pretty pricey so will have to wait for that one.

My next acquisitions will be many of the books recommeded here, but also some on Thomas Andrews, architectural drawings and various resources regarding Murdoch.
HAve a great day. Welcome to days!
I actually work days now...7:30-4pm should be but I normally am there til 7-8pm getting home late. But I have no one here and no cats any longer so I have put myself into my job and I have learned through the years to survive off little sleep going to bed around midnight and getting up at 4am generally. Getting to bed earlier...no warm snuggling there so its best to stay at worka dn stay out of trouble. Right!
Maureen.
 

Paul Rogers

Member
Jun 1, 2000
1,244
14
313
58
West Sussex, UK
Hi Maureen, Dean & Michael.

After reading various bits n bobs, I thought that I had got the breakup straight in my mind. I believed that the break started at the keel, sort of as follows:

(1) The keel compresses upwards at around boiler room nos. 1 and 2.
(2) The side plating of the ship bows outwards on both sides, to cope with the shortened keel length.
(3) The decking breaks at around the 2nd expansion joint, and the superstructure tears downwards towards the damaged plating and keel.

Now I've been really surprised by Michael saying that the keel area was not under great stress, and this confuses me totally! It almost sounds like the "hinge effect" as shown in Cameron's film, (you know, with the stern crashing down as if hinged at the keel), could be correct. And I had been laughing at that scene for the last 3 years as well!

Have I got it wrong again? And Michael, could you direct me to the later research please. I have a link to the Gibbs & Cox website, but I don't know where to find the '98 research. Thanks.

Regards,

Paul.
 
Jul 9, 2000
58,662
872
563
Easley South Carolina
Hello Paul, I wasn't the one saying the keel wasn't under great stress. Although Dean pointed out that it wasn't under as much stress as the portion of the superstructure that broke apart. I've been to the Gibbs and Cox site today to do a bit of rechecking. In the last view, there is a lot of red to indicate the stress on the superstructure in the region of and surrounding the second expansion joint and it was pretty widespread. I also noted that the area of stress on the keel in the area of the break wasn't as widespread, but it was that nice angry red color.

I for one don't beleive the hinge effect as dramitised on the film, but I wouldn't be surprised if the breaks began in several places at roughly the same time, but with the process accelerated once the keel gave up the ghost.

The '98 research is at least pertly available on Titanic, Answers From The Abyss, which I just ordered from Discovery Online. If anybody knows of an on line source which provides the '98 data in detail, I'd love to see it.

George, Dave, anybody? Help!

Mo, that's quite a list you have. I'll have to put a few of them on order next month when my Visa card isn't hanging on the ropes. I'm trying to get that two volumn Shipbuilder set too for it's information on other liners. Like the RMS Lusitania. I really want that information so I can discuss the matter with Geoff Whitfield a bit more intelligently.

Cordially,
Michael H. Standart
 

Paul Rogers

Member
Jun 1, 2000
1,244
14
313
58
West Sussex, UK
Sorry Michael - I meant to type "Dean," but didn't!

Looks like I'll have to get my credit card out again, and buy Answers From The Abyss. (It's getting too much, you know...the kids were on bread and water for the last week before payday. And all because I HAD to get Titanic At 2.00am!)

Regards,

Paul.
 
Sep 12, 2000
1,513
6
313
Dear Michael, Dean, Paul,
Your sharings on this topic is incredible and I think that I am beginning to understand all of this stuff. But I totally understand what you mean about having the books beside you and ready for the experts Michael. Guys like Geoff who know alot help keep us on focus. He's helped me to get back on track a few times and I really appreciate it.

I am probably one of the few women that you will ever know in your whole life who try to stay away from credit card purchases if at all possible. Other wise I would have 4387 books on Titanic in a cardboard box along with all of my belongings on the corner of ....whatever.... panhandling. But I can relate very well to the bread and water thing.

Now regarding the keel thing and the pressure. If I have a roll of french bread and there is a hollow section in the center of it and I place the right side of it into gravy, but I have places meatballs internally into the other end...won;t the greatest pressure be on the top of the center part of the loaf of french bread and not the bottom? Okay so I am desparate...but be kind okay...its late and I haven;t fixed my dinner yet.

(By the way, I have the greatest cheese cake recipe for you Paul that you can give to your wife as colateral for your next Titanic adventure.If you wish.)

Maureen.
 
D

Dean Manning

Guest
Hi everybody!

Paul, I didn't mean to imply that the keel wasn't under a great amount of stress.
happy.gif
As Michael pointed out, the colors that indicate stress were different around the keel area between the 96' and 98' finite element analysis models. I'll have to dig through my resources to try and figure out why this is. I have a hunch that there was a lot more accurate data used in the 98' model, which may also explain the differences in pressure quoted between the 96' and 98' expeditions.

I'm not so sure that I wouldn't by into the hinge thing. As far as I'm concerned, the bow and stern didn't separate until after they both left the surface. I think this because it's kind of hard to explain the stern's tattered condition if they had broke at the surface. So, with that said, let me explain why I think the hinge thing isn't that far fetched. After the stern leaves the water, at an angle of no more than about 12 degrees (this angle was determined from the finite element analysis) the stern starts to break away from the bow, from the top down. The hull breaks down to about the double bottom. At this point, what's holding the stern up? So, the stern falls back down into the water, where it starts to flood, but gets pulled under by the bow before it has a chance to completely fill. Once the ship leaves the surface, the bow and stern tug and pull at one another, each trying to go on separate paths. The bow and stern break away, along with a third piece, the double bottom and the keel. Ok, it's kinda far fetched, but it's my opinion. ;)

Michael, I seem to remember reading a mechanical engineering article about the breakup that was published after the 98' expedition. I think it contained detailed information about the actual split. I'll dig around and see if I can find it. If so, I'd be willing to send you a copy snail mail. And hopefully, the post office won't bend it!
happy.gif


I have to run.

-Dean
 
B

Bill DeSena

Guest
Good Day All !

Some of you expressed interest in my latest experiment the lifeboat drill. I am pleased to say it went well with my daughter's friends providing unwilling and noisy pasengers for the one boat being used at the local mariner.

I told my lab subjects that the ship was only slightly damaged and I wanted them to get into the boat. I also told them to picture the scene: the dark cold sea, the lack of urgency from authroties and the long 10 story distance in the dark from the boat deck to the sea. I wasn't too surprised that nobody wanted to get into the boat! One of the ladies was pushed into the bay by her sister then threw her sister in and tried to drown her, but aside from that little drama the test didn't have any danger. My 4 youngmen who served as seaman for the drill were happily grabbing the ladies and tossing them into the boat with riotous abandon until an 'officer' intervened and restored order.

Regards
Bill
 
Sep 12, 2000
1,513
6
313
Welcome back Bill! Great to hear that you survived the terrible ordeal with these....young ladies in bathing suits. What a hardship for you...you poor baby. I know that Pat and Mike Herbold and several others really just felt so badly for you and offered several times..nagged ...begged...wept loudly crying out to please let them go instead. But being the true fearless man that you are overcame your own...needs to throw women and children first...I mean place the little darlins into the boats.
Glad you survived Sir. But your intro section is full up Sir. Maureen.
 
Status
Not open for further replies.

Similar threads

Similar threads