paul.mercer wrote:What puzzles me is that pictures of the stern of Titanic seems to suggest that water pressure forced through the stern resulted in its almost total destruction, whereas the bow looks relatively intact although crumpled from impact with the sea bed. Bismarck of course was of a much stronger construction and it would seem unlikely that even though she lies around 3000 feet deeper than Titanic that pressure even at that depth would try to crush or blow out her hull.
Argh, to answer your question re Titanic’s stern verse bow condition Paul. As you recall the big T sunk by the bow, and the cause of sinking was from the flooding, so, the forward 'half' of the ship was already mostly / completely full of water, so 'inside' and 'outside' water pressure was basically equal in the bow as it descended, hence why we see it intact, or basically so.
As for the stern a different matter altogether, but I won’t get into where she broke (in 'half'), i.e. surface or subsurface, save to say it was not like in the movie, and Jim Cameron himself now flatly states that; but it was not flooded (much) so hence went down with most compartments full of air, and the deeper it descended it would have soon / eventually imploded with a mighty bang, which from the few 'implosions' I have seen underwater (of housed cameras, and diver propulsion vehicles or DPV's taken beyond their 'crush depth'), it seems / looks more like an explosion, given what the resultant damage done immediately looks like / begins to do (i.e. fall apart).
So one piece (the bow) went down already full of water at equal pressure as it descended shall we say, the other, the stern, started its descent mostly full of air, and imploded. Hence the difference in ‘look’.
So it is not water rushing ‘through’ the ship that crushes it or breaks it apart (although this does have some effect on internals), it is the external water pressure crushing any air filled pockets and in the process, if it is rapid enough as Titanic seems to have been, then that inrush from the implosion also breaks the ship / object apart. But hence why all these ship now sunk and on the bottom, even in very deep water, will remain un-crushed as they are already full of water (but will
slowly fall apart as the metal rots and collapses over the years).
Anyway, I hope I make myself clear in the above re why the crushing / implosion / ‘explosion’ occur, and why the two halves of the big T look so different.
And this 'waterloggedness' is why many ships that where torpedoed, and stayed afloat for a long time, are upright on the bottom, i.e. because they were already 'full' of water before they sank. HIJMS Haguro is a classic shallow water example of this (while on the other hand HMS Prince of Wales is not), and then we have Bismarck, Indianapolis, etc. all upright on the bottom in deep water. But of course the deeper the water a ship sinks in, especially a big ship, then its shape / weight 'distribution' has a tendency to get it 'upright' before hitting the bottom. On the other hand, if that same ship sank / left the surface very fast, basically still full of air, it would be crushed by the external water pressure increasing the deeper it went; or parts crushed (or slowly crushed depending of how fast - or slow as the case may be - the water can get into a compartment) as the effects of such can be seen in some of the pics in Bob Ballard’s book on 'The Lost Ships of Guadalcanal'.
paul.mercer wrote:What I would say is that if Bismarck was scuttled, then it took some very, very brave men to go below whilst she was being shot to pieces in order to set the charges off.
Roger that!!!!! You bet!