Bismarck construction flaws

Discussions about the history of the ship, technical details, etc.

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Dave Saxton
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Re: Bismarck construction flaws

Post by Dave Saxton » Fri Mar 22, 2013 3:26 am

There is no historical evidence of the stern section collapsing upon the rudders. This would not have escaped being noticed! Besides the stern section which detached can not collapse upon the rudders. The rudders are located underneath the stearing gear room foward of the section which was detached, and forward of the armoured transverse bulkhead that the section which detached, after the ship sank, was attached to.
The stern was so designed to reduce drag but was insufficienly armoured.


Actually the stern except for the most aft rounded section, which detached, was well armoured. The armour was the reason the very end section eventually detached. The very round end was a modular section added on, but the ship building protocols at the time of construction forbad welding directly to armoured bulkheads. Therefore attachment pieces were riveted to the bulkhead and the distal stern section was fillet welded to the attachment pieces. This was good design as far as was known at the time, because it would mean that for the welds to fail; several inches of each fillet weld would need be fractured. It was not known until the 1990s that shock waves can cause fillet welds to fail by deformation of the parent metal plates.
Prinz Eugen later in war had stern section blown off by British Submarine torpedo.


There's nothing unusual about this. Large torpedoes typically blew off stern sections, and bow sections, of cruisers during WWII.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Bismarck construction flaws

Post by sineatimorar » Sun Jun 23, 2013 8:51 am

One construction flaw could be caused by the reported shortage of the material used in the special welding rods. Something not fixed until dec 42.
The suggestion being that although the new Wh & Ww armor was weldable only the bomb/sea deck was fully welded, the rest was riveted.

This makes sense to me as the description of failure of the inner torpedo bulkhead while remaining in situ matches similar damage reports when the rivets themselves are 'Popped' by shearing forces. See port boiler room/generator room floodings due to shell and torpedo hits.

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Re: Bismarck construction flaws

Post by RF » Sun Jun 23, 2013 5:56 pm

Dave Saxton wrote: There's nothing unusual about this. Large torpedoes typically blew off stern sections, and bow sections, of cruisers during WWII.
Yes, another example was the Kormoran torpedo hit on HMAS Sydney - the bow forward of turret A sheared off some hours after the torpedo explosion, sinking the ship.
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Re: Bismarck construction flaws

Post by sineatimorar » Tue Jun 25, 2013 5:22 pm

If memory services me corectly the official RAN enquire found that while the torpedo hit together with the fires one made it impossible for the crew to evacuate the hull resulting in no survivors, the bow most likely sheared off under water after the actual sinking. The theory of the loss of the bow causing the sinking was just unfounded speculation at the time of the Wrecks discovery.

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Re: Bismarck construction flaws

Post by RF » Tue Jun 25, 2013 6:46 pm

To be sure you need to establish the cause of foundering. If the bow did shear off underwater then what caused the sinking? Logically perhaps shell hits below the waterline - but there isn't much evidence for this given the flat trajectory angles of German fire. Once the range had opened there would be a greater scope for such hits - an examination of the hull would be required to get at the answer.
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Re: Bismarck construction flaws

Post by sineatimorar » Mon Jul 08, 2013 4:05 pm

If you look hard enough at any torpedo protection system you will eventually find an Achilles heel.
This was manly due to the lack of empirical data available before a design was finalised.
The worst case was belated testing of the South Dakota's system. It hardly stand up to a 450 lb to 500 lb warhead!
This was found out too late to change the completed units of the Iowa class. Only the last two incomplete units were to be modified to withstand 600 to 700. lb warheads ( figure varies from source to source).
The reported figure of the KGV class of 1000lb is obviously propaganda generated bumpkin. It appears closer to 500lbs.

The Bismarck's system fails in my mind because, if it true, with the armoured torpedo bulkhead was RIVETED and NOT welded. The description matches with shearing failure of the rivets.I am still looking for confirming independent sources.

The other consideration here should be on how a design is operated. If operated in a manner outside of it's design parameters it will not matter diddle if it is a good or poor design.

As too the AAA system we all have to be aware of the power of 20/20 hind sight. While more weight was given over to this arrangement. It was considered AT THE TIME to have a dedicated AAA system as AT THE TIME, superior to most dual purpose cannon systems, heavy enough in relation to the surface combat, as they were too slow to successful defend against modern aircraft. The German fully stabilized AAA system while too Complex, successfully defended against most air attacks when the ship was fully underway when supported by 3d sighting posts. Something the Bismarck lacked in appropriate numbers as the design specified.

History is full of men in a great moments in time doing something outside of expected normal procedures or operating outside of design parameters. If they pull it off they are fated as visionary thinkers, if they fail, they are considered fools.

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Re: Bismarck construction flaws

Post by paul.mercer » Wed Jan 03, 2018 11:27 am

Gentlemen,
Re the stern of Bismarck detaching, did this not also occur on one or two German cruisers, if so, was there a design fault with the German engineering? Also, has it ever been determined as to why the stern broke away as it was described as being 'well armoured' in another post. I have often wondered if it was the combination of the torpedo hit and one or more hits from Rodney or PoW on the same area. I am assuming (rightly or wrongly) that the stern came off on or near the surface and not when the ship hit the bottom, which of course may have happened if she hit stern first and the stern was already weakened.

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Communication lines

Post by spicmart » Mon Oct 15, 2018 11:45 am

I frequently read at other places that Bismarck's com lines were a major flaw as they were located above the main armored deck without protection and thus easily knocked out early on in her final fight.
There is a drawing which show the communication devices installed beneath the armored deck. So were the cables and lines really above?

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Re: Communication lines

Post by RF » Tue Oct 16, 2018 5:43 pm

spicmart wrote:
Mon Oct 15, 2018 11:45 am
. So were the cables and lines really above?
Well, the gunnery control, bridge etc were exposed positions by definition and these are the places they can be knocked out..... a situation on any ship.
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Re: Communication lines

Post by spicmart » Tue Oct 16, 2018 6:53 pm

RF wrote:
Tue Oct 16, 2018 5:43 pm
Well, the gunnery control, bridge etc were exposed positions by definition and these are the places they can be knocked out..... a situation on any ship.
But it is often pointed out in debates as a particular weakness of Bismarck's compared to other BBs which are said to have "proper" protection in this regard.

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Re: Bismarck construction flaws

Post by spicmart » Thu Oct 18, 2018 12:01 pm

And did Bismarck suffer a hit in her boiler room during her final fight? Some claim so. Her vitals were supposed to be immune against such hits at these ranges.

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Re: Communication lines

Post by ede144 » Thu Oct 18, 2018 3:32 pm

spicmart wrote:
Tue Oct 16, 2018 6:53 pm
RF wrote:
Tue Oct 16, 2018 5:43 pm
Well, the gunnery control, bridge etc were exposed positions by definition and these are the places they can be knocked out..... a situation on any ship.
But it is often pointed out in debates as a particular weakness of Bismarck's compared to other BBs which are said to have "proper" protection in this regard.
No, the cabe Duces were located below main armored deck. And Cabling to bridge and directors were in armored cable ducts too.

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Re: Bismarck construction flaws

Post by ede144 » Thu Oct 18, 2018 3:35 pm

spicmart wrote:
Thu Oct 18, 2018 12:01 pm
And did Bismarck suffer a hit in her boiler room during her final fight? Some claim so. Her vitals were supposed to be immune against such hits at these ranges.
If you read the book from the Baron than there was no such hit. Even if no ship is immune against Shells fiert at point blank range. Fortunately or unfortunately BS was so low in the water that Rodney could not hit Magiers spaces.

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Re: Bismarck construction flaws

Post by spicmart » Fri Oct 19, 2018 10:42 am

Thanks.
So I conclude these are just biased claims made on some obviously biased forum?

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Re: Bismarck construction flaws

Post by RF » Fri Oct 19, 2018 6:22 pm

spicmart wrote:
Thu Oct 18, 2018 12:01 pm
And did Bismarck suffer a hit in her boiler room during her final fight? Some claim so. Her vitals were supposed to be immune against such hits at these ranges.
There may be some confusion here from the DS battle, where one of the three hits by POW did penetrate a boiler room, where five stokers suffered serious scald wounds.
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