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The sinking of MS Estonia: Case Reopened Part VII

JayUtah said:
Ductility is preferred over hardness. Most lay people have a completely unrealistic idea of how steel behaves at scale.
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Its something that 'normal' people 'don't get' in many subjects- and in many cases 'hard steel' is exactly what you DON'T want!!!!!

The truck trailers I used to haul for example would literally bend and flex anything up to 30cm/1ft when loaded and running- people would think that was a 'bad thing' when they saw them flexing- no, trying to make them rigid was the bad thing....
(in fact 'from the factory' they come with a 'reverse bend' built into them... which 'flattens out' when loaded- making a trailer out of non ductile steel ie hardened would be a BAD idea- it doesn't bend or flex- its stiff- until it reaches its breaking point- at which point it just snaps!!! :eek:)
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Like plane wings- those trailers were designed to flex and anyone making repairs or modifications had to be well aware of the actual engineering behind them, or you could actually make them a lot WEAKER by adding reinforcements to stop them flexing- strange as that may seem to the general public...
 
Much like, interestingly, tank armour.

People think that you want your tank to have the thickest armour possible, but no. You do want some thickness of course, but if it's too thick it may be too heavy, or alternatively make it difficult to mold into the right shape and fit together.

There's a reason no one makes heavy tanks and especially not super-heavy tanks anymore, put it like that.
 
Dabop said:
Its something that 'normal' people 'don't get' in many subjects- and in many cases 'hard steel' is exactly what you DON'T want!!!!!
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A ship's shell plating has one job: keep out water. That purpose is best served by something that responds to stress by bending first instead of fracturing.

Dabop said:
Like plane wings...
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When I used to fly on Boeing 747s to and from Europe, passengers would note (with some alarm) the degree of wingtip flexure. It was always my pleasure to tell them, "It has to bend or else it would break."

At the air museum where I volunteer, we have a B-52G on outdoor exhibit. Because of the slope on the display ground, one wingtip gear is firmly planted while the other one hangs about a meter above the sidewalk. The bigger kids (and some adult kids) like to jump on it and get the wingtip to dip, and they are pretty adept at getting it to bounce with proper cyclical application of weight. They can get that wing to bounce a good 15 or 20 cm at the tip, just by their own weight. Granted, that's all aluminum alloy. When we finally saw the Boeing 787 wing undergo its flex tests, even I could help saying, "Holy crap!" But again, that's composites.

A ship's hull will eventually fracture, and under far less stress than most lay people imagine. It is, after all, mild steel. That's why ship captains are strongly advised not to run into things. As I said, lay people generally have unrealistic expectations of how steel behaves at scale. The singular hole that Evertsson said he found is not an accurate depiction of what was actually there. There were also several smaller punctures and abrasions. That is much more consistent overall with seabed contact.
 
Mojo said:
You claim to have a degree in psychology. Was Myers-Briggs covered in the course? If so, was it regarded as valid for any purpose? If so, what purpose?
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As I said, the Myers-Brigg thing was a questionnaire sent around British Mensa by a psychologist around the late-80's or early-90's. Did you not hear this the first time? No, we didn't have Myers-Briggs re psychometrics.
 
Mojo said:
Obviously not, because if it had you would have realised that I was asking for the source for your claim that the JAIC said that a ship would float on its superstructure.

Here's the question again: what was the source for your claim that the JAIC said that a ship would float on its superstructure?
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When it said it floated on a 90° list. OK fair enough, but where do they show their calculations as to GOM, etc. To account for it sinking stern first, it brings in the concept of 'it must have been the aft windows on decks four and five wot got smashed by waves' to account for it, when the first common sense thought would be, OMG there's a breach in the hull let's look into that as a first priority!
 
JayUtah said:
Irrelevant.


Evertsson lied. He admitted he lied. Deal with it.


Straw man.


Ships don't sink by "falling into" water. Objects moving through fluids is something I've practiced professionally for decades. Show me your calculations. Impact of objects with other objects is also part of my decades of engineering experience. Show me your calculations there too.

I'll wait.
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Citation please of where 'Evertsson admitted he lied'.
 
Vixen said:
When it said it floated on a 90° list. OK fair enough, but where do they show their calculations as to GOM, etc.
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There is no such thing as "GOM." There is no point in trying to calculate intact-hull stability parameters for a ship that has flooded significantly. You're starting with the premise that Anders Björkman knows what he's talking about and is right. Instead try starting wit the premise that Anders Björkman is an obvious crackpot whose hand-wavy claims are nonsense.

Vixen said:
To account for it sinking stern first, it brings in the concept of 'it must have been the aft windows on decks four and five wot got smashed by waves' to account for it...
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No, that doesn't necessarily follow.

Vixen said:
...when the first common sense thought would be, OMG there's a breach in the hull let's look into that as a first priority!
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No, your layperson's common sense does not trump actual science and engineering.
 
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