bismark-after torpedo hit

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RF
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Re: bismark-after torpedo hit

Post by RF » Mon Apr 12, 2021 1:08 pm

paul.mercer wrote:
Mon Apr 12, 2021 10:25 am

Also, if tugs had got to her surely she would have constantly been tying to veer off to one side, putting an enormous strain on one of the tugs which would have also been battling heavy sea conditions?
How big and powerful were the available tugs, is there any info on this?
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Re: bismark-after torpedo hit

Post by wadinga » Mon Apr 12, 2021 6:02 pm

Hello RF and all,

Luckily we have amongst us one who has studied the wreck in detail, Bill Jurens, he has posted:
The general late-form consensus amongst those who have examined the damage in detail, is that the starboard rudder moved forward during the torpedo explosion -- there is a chunk of one stuck in the other (I can't remember which) -- which indicates that the impact took place while the propellers were turning. The most likely scenario is that the impact was brief, as there is not a lot of scoring on the propeller surface, and that the rudder moved back clear of the propeller almost immediately.

The additional damage and distortion probably inflicted on the bottom somewhat obscures the damage from the explosion itself -- they are somewhat, and probably inextricably, intermixed.
As for tugs, assuming they existed, even assuming they could maintain 10 knots in the wild conditions, (unlikely), they have to do a 300 mile transit, by which time it is all over. Well, they are probably in time to be shot to pieces themselves. There is no viable external rescue for Bismarck. I have never seen any indication, despite the Fuhrer's assurances, "All that can be done, is being done", any ships actually left a French harbour in a rescue attempt. Even the luckless crew of the oiler Ermland were only being "readied to sail" for what would undoubtedly be a suicidal sortie.

The neutral Spanish cruiser Canarias was despatched but was far too late to be of any assistance to Bismarck's survivors. As a heavy cruiser she could make far higher speed in the prevailing weather than any rescuers from France, and as a neutral would not be attacked when she arrived.

http://www.kbismarck.org/canarias3.html

Perhaps someone will start a hypothetical thread about Canarias arriving earlier and towing Bismarck to safety as a humanitarian gesture. Plenty of potential for an "International Incident".

All the best

wadinga
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Re: bismark-after torpedo hit

Post by Bill Jurens » Tue Apr 13, 2021 1:25 am

The tug idea is interesting, but I doubt very much if even big salvage tugs could have made much difference. Towing speeds would be too slow. Most tug-work took place in still-water harbors at very slow speeds. Pushing on the bow of the Queen Mary at three-knots in harbor is very very different than trying to push athwartships on the bow of Bismarck while she tried to make fifteen knots or so in heavy seas with British attack imminent at any moment.

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Re: bismark-after torpedo hit

Post by hans zurbriggen » Tue Apr 13, 2021 7:30 am

Thanks Mr.Wahl for providing the max RPM when reversing turbines. I doubt this is equivalent to long-time-sustainable power for 9 knots astern, mentioned by A-S-H, because 190 RPM point to a much higher speed ahead vs 280 RPM needed for 30 knots. Astern motion would be slower, but still more than 9 knots I was not able to find any data related to speed vs RPM -for any battleship-. Was anybody ?

Hello Mr.Mercer,
during night, Bismarck proceeded on erratic NW course @ around 6 knot, because, at slow speed, bow was kept into wind direction by force of wind. According to Reader, Bismack was at 400 sm from Brest when she received the hit and she sank at 450-470 sm from Brest, proceeding to NW, not circling (the circles were done only immediately after hit, with ship @ 28 knots).

Hello Mr.Wadinga, Mr.Mercer,
A-S-H has published on a reputed naval magazine (http://www.kbismarck.com/bismarck-seemannschaft.html) a study that shows how Bismarck still could have been steered, taking into account all factors: ship geometry, divergence of shafts, effect of water flow on hull and rudders, propulsion plant specifications, sea state and wind force as per may 26/27, presence of enemy forces.
A-S-H himself was very careful not to say it would have surely worked, and regretted in his article that no comparable ship was available at the time (2 rudders, 3 diverging shafts, fixed pitch propellers) to run a real test.
However, to counter his conclusions, we need a counter-study, showing he was wrong for any specific proven reason (e.g. there is no technical reason why Bismarck engines could run 9 knot astern in calm waters and not in a gale whose winds and waves are actually in favour to her motion to SE. Bismarck went all the night to NW at around 6 knots, against wind and waves).
Re. Bismarck turbines not designed to run astern for long time, actually they proved to be exceptionally resilient in operating out of their design specifications during desperate attempts to get her on stable course, ignoring intervals between full ahead and astern: ref. Baron). Why should they fail running astern when German experts said to A-S-H that it was sustainable ?

In the absence of any technical detailed counter-study, a probability that A-S-H theory could work still exists, despite (very respectfully) 'vast consensus' and 'diplomatic' conjectures here.

hans

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Re: bismark-after torpedo hit

Post by paul.mercer » Tue Apr 13, 2021 9:41 am

Gentlemen,
I have to agree with Wadinga, we have entered the hypothetical stage of this debate, all the evidence and theories put forward suggest that Bismarck was in an impossible position and it is doubtful that even if tugs had been available whether they would have been capable of towing a 50,000 ton ship in the prevailing conditions without the extreme danger of the tow line breaking and possible causing havoc to the tugs.
Like I said about the ideas of steaming in reverse, its one thing to tow a ship in calm waters and quite another to do it in an Atlantic gale, particularly with half the British fleet coming after you.
Let us also not forget that although KGV was short of fuel Rodney could have carried on for a bit longer and finished her off and even if Rodney had to retire the RN still had a carrier, a battleship (admittedly an old 'R') and a battlecruiser plus other assorted ships converging on Bismarck.
Let us just accept that, as almost everyone on this topic has stated, Bismarck was finished as soon as the torpedo hit her in the rudders and that in all probability the whole mission was doomed from the start.
What would have been far more dangerous situation is if Bismarck's mission had been delayed until the Twins were ready and they had rendezvoused somewhere out in the Atlantic - but that's for hypothetical situations!

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Re: bismark-after torpedo hit

Post by pgollin » Tue Apr 13, 2021 10:24 am

.

The British (and presumably all other mariime nations) had properly designed ocean going tugs, however they were built for producing pull and manoeverably rather than speed. The real problem was the size of the seas and the strength/durability of the cables.

Passing the cables would be difficult, however Bismarck would have the manpower/capstans to ease the problem. Just how strong Bismarck's anchor chains/holdfasts were is a question.

The moving seas will put immense strain on the cables/hold fasts as the cables slaken and suddenly become taut - cables snapped in much calmer conditions.

So the size of the seas is a major problem, but also the drag of jammed rudder would not only slow the tow, it also MIGHT mean that a second ocean going tug might be needed to keep the stern under some sort of control.

Not practicable.

.

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Re: bismark-after torpedo hit

Post by Steve Crandell » Tue Apr 13, 2021 4:39 pm

A previous post stated "(2 rudders, 3 diverging shafts, fixed pitch propellers) " and I was under the impression that Bismarck's shafts were converging.

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Re: bismark-after torpedo hit

Post by wadinga » Tue Apr 13, 2021 5:17 pm

Hello PGollin,

Yes indeed, there were more capable ocean-going tugs built when the need became obvious, such vessels as the British "Bustler" and "King Salvor" classes, of 1100 and 1400 tons respectively, which came into service 1942 onwards. Even these deployed only 4,000 shp. Many of the available French vessels escaped in 1940 and came into British service. I have suggested people view videos to get the feel of practical difficulties of establishing a tow and maintaining it in bad weather conditions.

It is worth noting Bustler, sold off into commercial service was the ship which lost the tow of Brazilian battleship Sao Paulo in bad weather, and which then disappeared without trace with her small passage crew.

Wishful thinking, like imagining tugs could cover 300, 400 or 450/470 miles in bad weather in a short enough time to be of any assistance at all, and the dearly-held faith it springs from is a powerful thing, and not easily dispelled by facts drawn from reality.

I don't wish to appear overly pedantic or to be critical of non english as first language posters (I am embarrassed by my inabilities in other languages) but this is incorrect I believe.
during night, Bismarck proceeded on erratic NW course @ around 6 knot, because, at slow speed, bow was kept into wind direction by force of wind.


A heading was deliberately selected where the westerly wind came in on the port side, somewhat off the bow, in order to counteract the unstoppable tendency to turn to port, caused by the rudder(s). This allowed forward power for only 6 knots to be used, since any more power would overwhelm the stabilising effect of the wind pressure, and result in another helpless circle to port. The crew, which was vastly more experienced in handling big ships, and specifically Bismarck, than any post war pundit with only small ship experience could possibly be, found this was the only course which allowed any stable heading to be maintained. They were well aware they were moving away from safety, at increased hazard for their lives, but as suggested, this course and resulting relative ship stability, gave them some chance of fighting the ship successfully, the moment a British force arrived. If it were Renown alone, there might be a chance of a another stunning success before Gotterdammerung.

For myself, it is the very suggestion by A S-H that any vessel the post-war Bundesmarine could provide would be in the slightest way comparable with the 50,000 ton Bismarck for a practical trial, that renders this highly-theoretical concept even less serious than might otherwise be the case, whatever journal it was published in. He apparently speaks in my poor computer translation of an "eligible" three screw ship in the-then current German navy. I wonder what that might be since the newish large "Hamburg" class destroyers of 4,000 tons were twin screw, as were the US designed vessels. He also seems inexplicably concerned about the effect on a comparison of using variable pitch propellers where the rotation direction remains the same, but the blades are adjusted to give reverse thrust, and ignores the significance that any hull would be a fraction of the displacement and length of Bismarck. Maybe he imagines using some passenger liner?

Speaking of reality, I discover reading the account of USS Intrepid's struggle to sail home that deploying a paravane was one of the suggestions for maintaining a desired course.

All the best

wadinga
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Re: bismark-after torpedo hit

Post by RF » Tue Apr 13, 2021 5:43 pm

paul.mercer wrote:
Tue Apr 13, 2021 9:41 am

What would have been far more dangerous situation is if Bismarck's mission had been delayed until the Twins were ready and they had rendezvoused somewhere out in the Atlantic - but that's for hypothetical situations!
That was precisely Lutjens advice to Raeder in early May 1941 but with Barbarossa looming Lutjens was overuled.
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Re: bismark-after torpedo hit

Post by hans zurbriggen » Thu Apr 15, 2021 7:00 am

Hello Mr.Wadinga,
sorry for my simplification (in my sentence quoted by you). My point to Mr.Mercer was just that Bismarck did not circle during night, but sailed to NW, loosing 50-70 sm toward France.

Very respectfully, I still suggest we would be better to agree to disagree on A-S-H proposal, instead of trying on your side to 'ridicule' it (saying it was 'highly-theoretical', not 'serious' and a 'pipe dream' with 'very shaky foundations' from a 'dyed-in-the-wool destroyer man', without providing factual evidence against his technical arguments), or on my side to defend it no matter what (without having the expertise to technically support it at all, I must admit).
You will be legitimately free to evaluate his theory a crazy one, based on your own experiences at sea; the Baron said it was the most plausible solution (even being convinced, as the junior G.O. he was, that it would not have worked, but admitting however it could have been tried "in peace" before); myself, being just an amateur sailor, I legitimately consider that it is well argued and supported and that it could have possibly worked, trusting his recognized authority in seamanship. That's all.

Instead, I think we can agree that, had it worked, Bismarck fate was not sealed even after the torpedo: @ 300 sm from Brest at dawn, any effort to further attack her would have cost a high price (or at least high risks) due to U-boots (potential) menace, Luftwaffe actual menace (range was down sufficiently, as per my previous post) and to fuel situation (critical for British heavy units, as Tovey was well aware of). It is doubtful whether light forces could have done anything against a battleship that could still return fire at them.

hans

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Re: bismark-after torpedo hit

Post by wadinga » Thu Apr 15, 2021 10:26 am

Hello Hans,

So equally respectfully we shall agree to disagree on the value of A S-H's proposal, but I would like to observe I have not called either him or it "crazy",

All the best

wadinga
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Re: bismark-after torpedo hit

Post by Herr Nilsson » Thu Apr 15, 2021 11:58 am

From Tirpitz' "Schiffbuch II" from July 22nd 1941
Tirpitz Dreheigenschaften .jpg
Tirpitz Dreheigenschaften .jpg (30.84 KiB) Viewed 380 times
The ship cannot be steered when sailing over the stern, rather it tends to go with the stern into the wind. Once it has started to turn, it cannot be stopped even by unbalanced engine speed and the opposite rudder position.
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Marc

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Re: bismark-after torpedo hit

Post by Steve Crandell » Thu Apr 15, 2021 3:01 pm

Herr Nilsson wrote:
Thu Apr 15, 2021 11:58 am
From Tirpitz' "Schiffbuch II" from July 22nd 1941
Tirpitz Dreheigenschaften .jpg
The ship cannot be steered when sailing over the stern, rather it tends to go with the stern into the wind. Once it has started to turn, it cannot be stopped even by unbalanced engine speed and the opposite rudder position.
I think that pretty much says it all.

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Re: bismark-after torpedo hit

Post by hans zurbriggen » Sat Apr 17, 2021 6:36 am

Hello Herr Nilsson,
in his article, A-S-H was well aware of such inconvenient behaviour (my poor translation): "However, ships sailing astern have strong tendency to turn stern to wind because pivot point has moved astern".
Was Tirpitz sailing using A-S-H's method ? "So, in case of Bismarck in high seas, an anchor hoisted out with around one length of chain probably would have had this effect" (= same drag effect of chain in harbor)

hans

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Re: bismark-after torpedo hit

Post by paul.mercer » Sat Apr 17, 2021 9:17 am

Gentlemen,
I don't know what sort of weight Bismarck's anchor would be, but I would have thought that something of that size and weight dangling from the end of a chain would be almost uncontrollable and likely to be highly dangerous to the ship plunging about in a heavy sea. It is also doubtful if it would have made much if any, difference to a 50,000 ton ship steaming at low speed anyway.
Look, we have discussed almost every possibility of saving Bismarck in this topic and before on this Forum which has some extremely knowledgeable contributors - far more than myself and not one has come up with a viable solution and the general opinion being is that once her rudders were damaged there was no way back home, particularly with half the British navy looking for her. Both Lutyens and Lindermann knew it and so did most of the crew. I'm afraid that further hypothesizing on this subject is getting a bit pointless.

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