Bismarck construction flaws

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

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Javier L.
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Post by Javier L. » Fri May 20, 2005 12:12 am

Bill, Tommy, I'm not sure what defect you are talking about in the side protection system. Could you please attach a cross section drawing for us to see? Thank you.

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Protection

Post by Bill Jurens » Fri May 20, 2005 12:43 am

I don't know how to post a picture, but will try another explanation. Get a cross-section near amidships. Place yourself inside the engineering spaces and walk outboard along the inner bottom until you reach the bottom of the holding bulkhead. Right there, at the 'toe' of your shoe, is the single thickness weak point...

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Post by tommy303 » Fri May 20, 2005 3:03 pm

Bill,

I was looking over the drawings by G & D and they show that void area outboard of the torpedo bulkhead at the point in question as being the lower oil fuel bunk, there being one for water and one for oil immediately above it. It wasnt therefore completely an unprotected area in regards to splinters, but i can still question the wisdom of having the tank boundary anchored to the torpedo bulkhead above the double bottom boundary where it would be better supported. Perhaps the structure of the liquid loaded tanks was kept extremely light to prevent high stress loadings on the bulkhead during torpedo detonations?

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side protection

Post by Bill Jurens » Fri May 20, 2005 4:12 pm

Whether this tank would be full or not depends somewhat upon the liquid loading arrangments and counter-flooding arrangements, but I expect that in action splinters and/or near miss explosion damage might flood many of these outboard spaces quite quickly anyway.

In that case, you are in effect even worse off. Splinters disappear, but with fluid in the tank, hydraulic forces from the blast itself would be transmitted more-or-less directly to this single layer shell, and -- as is noted in all torpedo protection systems -- deflection and/or failure of inboard bulkheads in the system is not only common, it's to be expected.

The point is is that if a torpedo detonates on the shell outboard, you have at that point only this single layer of steel between yourself and the ocean. Further, because the 'defect' is located low down in the engineering spaces, it is likely to be a spot difficult to access even if dry, and impossible to access once the water gets to be more than a meter or so deep. This makes it very difficult to plug even minor damage. Regardless of other geometry, at this point -- the weak link -- his is a 'one layer'one bulkhead system' at best.

This is the sort of arrangement one might expect, and tolerate, on a cruiser...

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Post by tommy303 » Fri May 20, 2005 11:21 pm

Bill,

I most certainly agree that these spaces would be difficult to reach and even more difficult to work in if you had to stop leaks. If I recall correctly the boilers took up so much compartment space that they went nearly to the torpedo bulkhead--which was the reason given for the wireway/passageway not being carried all the way down to the inner bottom as a full auxiliary holding buikhead in that area, although it apparently is present in other areas outside of the engineering spaces.

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Post by José M. Rico » Fri May 20, 2005 11:56 pm

Javier L. wrote:Bill, Tommy, I'm not sure what defect you are talking about in the side protection system. Could you please attach a cross section drawing for us to see? Thank you.
If I understood this correctly the red arrow in the cross section below marks the place Bill is talking about.

Image

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Post by tommy303 » Sat May 21, 2005 12:23 am

yes. at least that is what i have been looking at, and i think Bill too.

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Side protection

Post by Bill Jurens » Sat May 21, 2005 3:29 am

Yes. That is indeed the area of concern.

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Drawing source

Post by Bill Jurens » Sat May 21, 2005 5:31 pm

As an aside, I find the cross sectional drawing Jose posted to illustrate this thread of interest. Can Jose provide a source, please?

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Post by José M. Rico » Sat May 21, 2005 6:04 pm

Sure. It is a cross sectional drawing in 1:100 scale of the battleship Tirpitz (Kriegsmarinewerft Wilhelmshaven in July 1941) scanned for us by our Polish friend Miroslav Skwiot and originally from Breyer. I believe copies of the complete original set are available at the Bundesarchiv/Militärarchiv.

Skwiot's Bismarck/Tirpitz publications from AJ-PRESS also include a set of these drawings reduced to 1:400 scale.

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Post by Tiornu » Sat May 21, 2005 10:30 pm

If you look in Breyer, you will see that old Deutschland's torpedo protection includes the double bottom being extended up the ship's side. Just as the double bottom consists of individual cells, so does this extended coverage. In other words, the little rectangles visible in the cross section of the double bottom are turned on their side as they continue past the turn of the bilge and up the side. The surface that was the side of a bottom cell becomes a horizontal shelf in the side cells.
This was a logical step in the evolution of underwater protection from ships of the 19th Century, and you will see it even in some cruisers of WWII. In Deutschland's case, there is also at least one torpedo bulkhead inboard of this double layer. At one point, German designers were adding additional bulkheads in such a way that they were on the verge of inventing the "American" system of torpedo protection about ten years before the Americans did. If you have a copy of McLaughlin's book on Russian battleships, you can see on p 216 the B&V proposal submitted to the Russians. It looks very "American"! However, notice that the first bulkhead is contiguous with the upper layer of the double bottom. The shelves have been eliminated, but the last cell side is the one that is angled at 45deg and points directly to the turn of the bilge.
From no later than the Konig design, the Germans had eliminated all shelves in the outer layer, though that 45deg surface at the turn of the bilge recurs in many (not all) classes. In Bayern, we see something very interesting. The inner surface of the double "side" carries directly down to the bottom, so there's no 45deg surface. (Don't worry, it'll be back again.) More importantly, the double bottom has another surface above it; it's a triple bottom. Unlike the double bottom, the triple bottom does not reach beyond the torpedo bulkhead. Next we have Mackensen. The 45deg surface is here, and the inner surface of the double side connects not to the double bottom, but the triple bottom. We have come very close to Bismarck, with three major differences. One, the inner cell is not divided in Mackensen. Two, there is no slope armor in Mackensen, so the top of the system is arranged differently. Three, the triple bottom is contiguous with the inner surface of the double side.
Now, Number 3 is the important point.
If you imagine Bismarck with an added layer giving her a triple bottom, and you go to the engineering spaces as Bill described, the toe of your boot is no longer tapping against the only surface between you and the outer hull plating; there is also the inner surface of the double side.
CAN IT BE that the Bismarck designers simply removed the triple bottom and failed to lower the last cell of the double side to connect with the double bottom? That is how it appears. I understand that triple bottoms were found to be no advantage over double bottoms of similar depth. I can't help thinking they just eliminated one feature without regard for its relationship to the rest of the system. Such a mistake from an overworked and underqualified design bureau would not surprise me.
Note that I am depending heavily on Breyer.
Any thoughts? Does this make sense?

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Post by Javier L. » Sun May 22, 2005 12:07 am

Thank you all. I see now what you mean.
That is not a good place to receive damage, but I want to ask: considering Bismarck's draft, what are the chances of a torpedo hitting down there? It must be set at a depth of at least 8 meters to hit there amidships. What is the average depth setting for torpedoes?

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Post by Dave Saxton » Mon May 23, 2005 2:35 am

Tiornu wrote:........
. I can't help thinking they just eliminated one feature without regard for its relationship to the rest of the system. Such a mistake from an overworked and underqualified design bureau would not surprise me.
Note that I am depending heavily on Breyer.
Any thoughts? Does this make sense?
IIRC, G&D proposed a similar thought. IIRC, G&D wrote that an secondary holding bulkhead as designed was dropped during construction to make additional room for machinery mounts. In my Tirpitz drawings, this lack of overlap is present at some frames, but not at other frame (see frame I think ~464). It is present at some machinery compartment (see frames 149-150 for example) and at some magazines were one may expect an additional designed in but deleted bulkhead, as G&D propose. I agree that this was a potential weakness, but the bulkhead in question is not just an ordinary bulkhead, but the continious 45mm Ww, on a reported 20mm ST52 backing. The material forming the seperation between void and liquid load may have been Wh, additionally. Out board of the point in question, the double bottom tank is labeled "heizolvorr-B". It looks to be a continuation of the liquid load inboard of and below the void, but carried out to the shell at the bottom, thereby surrounding the void. In my opinion, I don't see this as a major fault, but a potential weakness nonetheless.

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Side Protection System

Post by Bill Jurens » Mon May 23, 2005 4:18 am

I won't argue the point, but to call this anything but a major design error is, I think, highly understating the case.

So far as I know this arrangement represents virtually the only 'single layer' protective system of any battleship designed after World War I. You won't see another system like it, except perhaps on Scharnhorst/ Gneisenau.

Placing one's faith upon ANY single bulkhead that close to the shell --without any backup at all -- and further placing that point of vulnerability in such an inconvenient place represents, in my opinion, a very major flaw indeed.

Not only is the arrangment vulnerable to low-running torpedoes, it's very vulnerable to mine explosions and/or grounding damage. Further, although this does not affect the design process per se, the Allies knew about the flaw whilst Tirpitz was still in service.

It's a bad one...

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Post by foeth » Mon May 23, 2005 12:13 pm

Filling the single protective layer with oil also seems to be a drawback, a single torpedo hit could rupture both outer skin and inner bulkhead, filling the boiler room with fuel oil, which sounds rather flamable. Combined with that blukhead between center and outbaord boiler rooms, she could developed a nasty list.

This small design fault could be remedied quite easily with some protective casing, perhaps it was?

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