Costa Concordia

I wish you'd been there. I'd have beat his fist in with your head.

Reply to
Grimly Curmudgeon
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On Sun, 16 Sep 2012 22:53:34 +0100, "Doctor Drivel" wrote:

The two statements are not mutually excusive. The Sunderland design was of riveted construction. The Liberty ships were welded as that allowed a large amount of prefabrication,use of labour who could be trained to weld easily and that all allowed them to be built quickly in large numbers. What wasn't expected at the time or really known about was when a crack on a steel plate on a riveted ship occurs it usaully stops at the edge of the plate where it joins the next one. Many riveted ships probably had cracks in them for ages before they became big enough to be noticed and the plate repaired. On the Libertys the cracks spread quickly across the welds into adjoining sections causing some catastrophic break ups until research showed the cause. The Square cornered hatches happened to be near a weld that was quite stressed and were a point of origin for such cracks. Modifications were done and lessons learnt and applied to the Victorys. Many libertys lasted well past their 5 year design life in the merchant navies of several countries until the mid 60's. In a nice example of a wheel turning full circle many were replaced by another Sunderland design the SD14 ,a design so popular that in a final flourish for British shipbuilding over a hundred were built here and an equal number abroad until the late 1980's. I was able to visit an original liberty ship when it visited Southampton for the 50 years commeration of D day in 1994,what was touching is that many of the crew were veterans of the original event and although they had some younger people around to help had been determined to do the journey back to the beaches one more time.

G.Harman

Reply to
damduck-egg

no he doesn't. You are both right. This was covered in the "materials" part of my degree course. The steel used by the US shipyards was one which became brittle when cold. This was fine for rivetted construction, but dangerous for a welded ship since a crack could run through the entire structure. Minimising the causes of cracks was an obvious partial solution.

Reply to
charles

This man is clearly mad.

The wartime investigations noted a failure in the steel. A part of the investigation attempted to codify the rules of thumb used in ship building and measure what sort of stresses were met. Simply put some of the steel was not up to the task. Certainly one remedial action, with significant safety gains, is to look through the ship and reinforce areas subject to higher stress, or change things to reduce the stress. Longer term comes a design that minimises high stress areas.

Better stress designed Liberty ships should have resulted in less cracking, but ships using other steels did not encounter problems. This was an initial complication for the investigation but obviously also provided a clue.

In summary the metal failed, a better design would have reduced the problem but not eliminated it. To put it another way if a design requires materials to handle a level of stress that the standard tests say the material can do, then the material fails in a rather obscure set of circumstances is that a design or materials fault?

The square versus rounded corner hatches as a way of reducing local stresses was not known well enough at the time, so much that de Havilland put square windows in the original version of the Comet airliner, with catastrophic results.

Reply to
Doctor Drivel

If your fist came anywhere near my head it would be severed.

Reply to
Doctor Drivel

The steel used was not suitable for the low temperatures encounted in the North Atlantic.

One ship broke in two when a nightwatchman ( the ship was in dry dock) tapped his pipe out on a bridge rail. Nothing to do with hatch design.

Reply to
charles

Must have been one helluva pipe, though.

Reply to
Grimly Curmudgeon

No doubt that is what he said at the enquiry, maybe we will never know the true story :)

Reply to
The Other Mike

The herald of free enterprise sank when I got on the Calais ferry. I never knew I had that much psychic power.

Oddly enough, the following Monday when I got on it to go back to Brussels, they were playing Mile Oldfield 'never get to France' on the Tannoy.

Sick bastards.

Reply to
The Natural Philosopher

The failure to which you refer was due to brittle fracture. I believe it was a T2 class Tanker

Reply to
Edward W. Thompson

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