2,000 tons of seawater in Bismarck's forecastle!

[Javier L.]

Hello all,

Müllenheim-Rechberg writes in his book about the hit in Bismarck's forecastle during the battle of the Denmark Strait (page 150, 2001 edition published by Birlinn Limited):

"That first hit, forward of the armoured transverse bulkhead in the forecastle, passed completely through the ship from port to starboard above the waterline but below the bow wave. It damaged the bulkheads between Compartments XX and XXI and Compartments XXI and XXII and left a one-and-a-half-meter hole in the exit side. It also ripped up several wing and double bottom tanks. Before long we had nearly 2,000 tons of seawater in our forecastle."

2,000 tons!! Isn't it too much water? Is there enough room in those flooded compartments to hold 2,000 m3?

[RF]

I am curious as to how the Baron had arrived at that figure, particulary as the Germans used metric notation and not English imperial measures or their US equivalent. Has there been a misquote or mistranslation here?

[marcelo_malara]

I would say that multiplying the surface of the compartments by the water depth in them. One cubit meter of water equals about one (metric) ton, which is close to the Imperial ton.

[RNfanDan]

Keep in mind, since the ship was leaving a slick in her wake, at least some of that seawater merely displaced what had been taken up by oil fuel. It wasn't 100% additional loading, but at least one fuel bunker and possibly two, were involved.

Kennedy, in his book Pursuit wrote: "The third and most serious hit had...penetrated two oil tanks, come out the starboard side without exploding. This hit not only let sea-water into the oil tanks and quantities of oil into the sea, but knocked out the suction valves, cut off from the engines a further thousand tons of oil." [Viking Press, 1974, p.98].

Another thing to remember is that, oil fuel being lighter, any equivalent physical volume of seawater will weigh more than the oil it displaces. An aggregate increase of 2000 tons might be unrealistic, but most certainly the flooded non-fuel compartments, combined with the displaced oil fuel, may very well have allowed 2,000 tons' worth of seawater to replace both air and oil.

Perhaps someone with an interior schematic of the ship forward, may be able to estimate just how much additional weight was taken-on in the flooded "dry" compartments that were holed, and from there a certain amount of guesswork applies to the oil-displacement question.

Yes/No?

[Bill Jurens]

By pure coincidence, I recently did a great deal of computational work on Bismarck's hydrostatics whilst completing an unrelated project. I can share some of that now.

The flooding on Bismarck from this forward hit apparently extended from Frame 203 to Frame 224. Although flooding may not have been immediate in all spaces, it is reasonable to assume that this volume was, within an hour or so, flooded solid to the 9.6 meter waterline.

The enclosed volume of the spaces between Frames 203-224 is approximately 811 cubic meters. Flooded solid, and using nominal values for the position of the center of buoyancy. "tons per inch" immersion, and trimming moment, this would produce a trim of about 1.2 meters, and an increase in draft of about 1.42 meters. This calculation assumes a volume permiability of 100%, i.e. that the spaces involved were absolutely empty. This is, in fact, unlikely, and probably impossible; in practical terms, due to internal structure even 'empty' fuel tanks typically have a volume permiability of only about 95%. Most 'normal' spaces have a volume permiability of about 85%. Clearly, if the lower fuel tanks were full when the damage was received, their volume permiability would have been essentially zero. Because we do not know how many of the lower fuel tanks were full or partially full when the damage was received, the overall volume permiability of the spaces under consideration remains somewhat conjectural.

Assuming -- and it's a big assumption -- that the overall volume permiability was about 75% -- meaning that at least some of the lower fuel tanks were partially full already, we get a net flooding volume of about 608 tons, a trim of about 0.9 meters, and a draft increase of about 1.06 meters. List, because the flooding was probably symmetrical about the centerline, would have likely been zero.

Certainly, the information I have would not seem to justify an estimate of 2000 (or even 1000) tons of flooding water forward.

Bill Jurens

[RNfanDan]

There are few things I enjoy more than an expert's considered opinion! Thank you

[dunmunro]

Certainly, the information I have would not seem to justify an estimate of 2000 (or even 1000) tons of flooding water forward.

Bill, have you considered flooding from all causes (IE the hit in the machinery spaces) and the need to counterflood to restore trim and correct list?

[Bill Jurens]

No. The quotes in question -- and the name of this thread -- seems to specify that the flooding related only to the forecastle areas, so that is the only calculation I discussed, or provided.

Bill Jurens

[José M. Rico]

The enclosed volume of the spaces between Frames 203-224 is approximately 811 cubic meters.

Bill, is that the volume that corresponds to the spaces in the upper and middle platform decks only, or is it the total volume of everything from the lower tanks to the waterline? I ask becasue if I remember correctly after the hit in the forward section and the subsequent flooding, 1,000 tons of fuel oil were supposedly blocked in the lower tanks. That would make the total volume considerably higher than your figure.

[Bill Jurens]

The volume given is taken from a curve of sectional areas, derived from the lines plan. In this case, it includes all of the volume between the base line and the nominal design waterline, which I have set for computational purposes to be 9.6 meters. The figures were adapted from my unpublished paper "A PRELIMINARY RECONSTRUCTION OF THE STABILITY CHARACTERISTICS OF THE GERMAN BATTLESHIP BISMARCK"
which I completed in February of this year. The flooding extents were taken from diagrams provided via Josef Statz, who worked in Bismark's damage control organization.

The German's subsequent inability to access fuel in tanks adjacent to (and in some cases somewhat removed from) the area of initial damage does not mean that these compartments were flooded, only that their contents were inaccessible. It is possible that some flooding of fairly remote (and previously empty) tanks may have occurred through ruptured piping if the manifolds in the pump room were damaged -- practice varied from navy to navy and sometimes from ship to ship -- but there is no indication of significant flooding elsewhere on the diagrams I have. Even in the worst case, downflooding of remote and empty tanks could have easily been prevented -- or at least greatly slowed down -- by simply closing the air escape valves.

It is, in any case, unknown (at least to me) how many of the forward reserve fuel oil tanks were full how many were empty before the damage occurred. German commentary that the loss of access to these tanks was in some way significant suggests, however, that at least some of them were full. Had they been empty, the Germans would not have cared much about the loss of access to them.

The pump-room on Bismarck, was, incidentally, located in a rather vulnerable location; most other navies placed such spaces low down and further aft, either just ahead of Turret I, or even 'inside armor' behind the forward transverse armored bulkhead. It appears that the location in Bismarck was chosen because of convenience in handling fuel, specifically because the tanks forward were considered to be at least potential storage for refueling other vessels and because the Germans had adopted a system whereby fueling was done over the bow, with the designer simply (and reasonably) placing the pump room close to where the fueling lines were located. The inability to pump from isolated tanks would not be considered unusual, few navies provided more than a single suppy or suction line from a given tank.

The forward tanks may have been filled in order to permit re-fueling Prinz Eugen, but that is mere speculation.

It is important not to put too much weight on the informal accounts of survivors, etc., including the Baron. One must remember that the Baron was hardly a technician, and there would have been little reason to share details of the forward flooding with him, or for him to remember them. Often, survivor's accounts owe as much to the 'rumor-mill' as they do to actual observation and/or knowledge of the situation.

Bill Jurens

[José M. Rico]

Thanks for your reply Bill.

I'm attaching a drawing of the forward sections. You calculated the volume of the spaces in green and blue, right?

bsbow01.jpg (49.59 KiB) Viewed 6504 times

By the way, do we know if the flooding also extended to section XXII?

[Bill Jurens]

Yes. I think your diagram is correct. I did not compute the volume marked in blue up to the deckhead, only to the 9.6 meter waterline.

Bill Jurens

[paul mercer]

Kennedy, in his book Pursuit wrote: "The third and most serious hit had...penetrated two oil tanks, come out the starboard side without exploding. This hit not only let sea-water into the oil tanks and quantities of oil into the sea, but knocked out the suction valves, cut off from the engines a further thousand tons of oil." [Viking Press, 1974, p.98].

Any ideas as to what would have happened if the shell HAD exploded?

[Bgile]

The shell wasn't designed to explode under those conditions. It's kind of like hypothesizing about the shell that hit the PoW compass platform. What if it had done something it wasn't physically designed to do? Pretty unlikely I think. It seems more likely for an AP shell to not explode than for it to explode early.

[RF]

These sort of situations about shells exploding or not exploding can be debated for ever - but I think that saying ''it didn't explode at that point because it wasn't designed to'' doesn't get around the fact that it could have exploded, designed to or not, as ordnance sometimes does mis-behave; the question ''what damage would it have done if it had exploded'' is still a fair question, even if any answers given are purely academic as to what happened in reality.