bismark-after torpedo hit

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

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wadinga
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Re: bismark-after torpedo hit

Post by wadinga » Sat Apr 17, 2021 9:44 am

Hello Steve,

You really cannot douse the feeble, flickering light of hope with such a cold-water douche of reality. On Tirpitz' trials they clearly did not try dangling an anchor off the bows, or trail a loop of hemp hawser and some will continue to believe these small boat drogue techniques might have given a 50,000 battleship some astern manoeuvrability, when it apparently had none, even with undamaged steering gear. Gale force winds and heavy Atlantic seas might perhaps have helped the situation, rather than hindering, but for those who have experienced such conditions it seems unlikely. They who want to believe will maintain that right, whatever actual evidence is presented.

A S-H's study has some simple diagrams, but tellingly no real-world examples of ships sailing astern for lengthy periods even with fully operational steering gear. Dragging an anchor chain across the sea bed would indeed produce enormous drag and resistance to the bow swinging around due to windage. However an anchor and chain dangling in deep water only has hydrodynamic drag in proportion to speed, and if the speed is slow the drag is low. The only real world example he presents refers to a much smaller ship, with a different rudder configuration and only refers to forward motion in presumably relatively calm conditions. He then extrapolates wildly to a very different ship, in different conditions travelling astern and provides no supporting evidence for his speculative ideas.

Whilst Herr Nilsson is here with us maybe he can detect from the German text whether the numbered references in Kp z See Alfred Schulze-Hinrichs' article (Marine-Offizer-Verband Nachrichten, Vol 17, No. 1, 1968.) refer to to 'Handbuch der Seemannschaft; pub 1967 Wehr and Wissen in Darmstadt. He was the author of this work as well, and of course it never hurts sales to have a contentious and probably irresolvable argument raging when you have a new book out on the subject. :angel:

Herr Nilsson: :clap: :clap: :clap: (As usual)

All the best

wadinga
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Steve Crandell
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Re: bismark-after torpedo hit

Post by Steve Crandell » Sat Apr 17, 2021 4:00 pm

Even if you were dragging the anchor and chain on the seabed, it would be difficult to steer the ship in the desired direction without a functioning rudder. You would have much greater directional stability, but what direction?

Thorsten Wahl
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Re: bismark-after torpedo hit

Post by Thorsten Wahl » Sun Apr 18, 2021 12:19 pm

Given the informations we have from the last battle, the behavior of the ship at given certain wind conditions(without using rudder) and a considerable ruddereffect by the remains of the rudders, the ship had only limited steering abilities against the main wind/wave direction by changing individual shaft RPM.

Under less severe athmospheric conditions a limited steerability in any direction may be possible, but at almost storm condition given the tendency to turn into the wind, another result as the historical appears unevitable for me.

And we should not forget the ship had no support from own forces and no available time for preparation of countermeasures for the rudder effect.
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Re: bismark-after torpedo hit

Post by wadinga » Sun Apr 18, 2021 1:48 pm

Hello Thorsten,

I am glad we agree about Bismarck's limited steering capability, but
and no available time for preparation of countermeasures for the rudder effect.
have you considered my suggestion for using paravanes to counteract the rudder effect?

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"

Bill Jurens
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Re: bismark-after torpedo hit

Post by Bill Jurens » Mon Apr 19, 2021 2:44 am

I haven't done any calculations, but my suspicion is that paravanes even if streamed at speed would not be able to exert enough transverse force to make any significant difference. They were, after all, only intended to move minesweeping wires outboard and to support a fairly light cable to cut the mine float wires. Basically, the ones that 'came with the ship' were probably just not big enough. And, of course, Bismarck couldn't really make much speed to begin with, so paravane 'traction', which, like a kite, is dependent upon speed, would probably be fairly minimal.

Bill Jurens

hans zurbriggen
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Re: bismark-after torpedo hit

Post by hans zurbriggen » Mon Apr 19, 2021 7:15 am

Hello Mr.Mercer, Mr.Wadinga, Mr.Crandell,
we had previously 'agreed to agree to disagree' (sorry for the word pun), but , as you have done the same, think I may answer.
A-S-H took into account any possible objection to his theory (e.g. recently evidenced tendency to turn stern into wind when going astern, and also all the other objections previously brought forward here). Again, I don't say (and A-S-H didn't say as well) that it would have worked for sure. I just say it had a probability to work but that it was not tried on board.
Answering Mr.Crandell question, anchor + wind + selected engines revolutions (+ possibly loop of hemp hawser only to 'lenghten' ship to cope wave lenght, not as drogue technique) would have produced stable course 110°, according to A-S-H study.
Regarding ' knowledgeable contributors' here, I agree there are, but I strongly doubt anyone has seamanship competence even remotely comparable to A-S-H one. Has anyone published books on seamanship, as he did from 1943 to 1967 ?

Who believes that he was wrong in his article or he was just 'looking for advertising' is free to do so. I think his method could have actually worked for Bismarck, giving her a chance.

hans

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Re: bismark-after torpedo hit

Post by paul.mercer » Mon Apr 19, 2021 9:33 am

Hi Hans,
i think you should have another look at my last post again re trailing an anchor, as well my comment on the rather fruitless point of continually hypothesizing about the possibilities of saving the ship in the face of all the other posts regarding the impossible task of getting Bismarck home before the RN caught up with her.
Mr A-S-H may be a very experienced seaman, but so were Lutyens and Lindermann and no doubt other senior officers as well, one does not become a Captain and Admiral on a ship that was the pride of Germany without knowing what to do in an emergency and trying to save their ship even under the most difficult conditions.
Had the sea been flat calm then there may have just and only just, the possibility of doing something to free the rudder or rig up a form of sea anchor,
but even if they had the speed at which they could steam would have been very slow. The RN knew where she was and would just have caught up with her a bit later.

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Re: bismark-after torpedo hit

Post by wadinga » Mon Apr 19, 2021 10:17 am

Hello All,

Bill has suspicioned paravane "pull" might be insufficient, but on the Raumotter thread we have have a link to a WWI graph showing tow loads of 1-4 tons in the 10-20 knot speed range and Marcelo the Maths Whiz has come up with similar estimated figures from first principles.

In debates on the subject the case of the jammed rudder USS Intrepid has been referenced before, the declassified USN confidential document is at http://www.researcheratlarge.com/Ships/ ... ering.html

and makes fascinating reading.

Amongst things suggested but not in the event tried:
9. Further steps which could have been taken but which proved to be unnecessary during the INTREPID's voyage are as follows:
(a) Rig a paravane on one side. A paravane creates a very considerable pull on its towing cable and would materially assist in keeping the bow out of the wind, if rigged on the leeward bow.
Something not suggested in it was sailing to safety backwards, even though as previously noted US carriers did try out "landings over the bow" whilst the ship proceeded astern.

If one paravane "creates a very considerable pull", what can eight do?

I am unclear why with undamaged steam plant and propellers Bismarck
couldn't really make much speed to begin with,
except that turning and an angled rudder inevitably dissipates speed. Full ahead power on all engines resulted in circling to port, but at what speed? They chose to steam slowly because that created the balance between weather "Off the bow" and rudder effect, allowing a relatively stable but undesirable course to be steered.

Like A S-H's proposal there is no guarantee this would work, but unlike his, it uses practised techniques and equipment available in the ship and I believe it would have been feasible, unlike these other suggestions, and worth a try.

All the best

wadinga
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Re: bismark-after torpedo hit

Post by pgollin » Mon Apr 19, 2021 10:59 am

.

Paravanes (pairs) made the modernised British battleships and KGVs lose 1 to 2 knots depending on which set-up was used. The other (possibly) available minesweeping item available might be an otter board (used in some minesweping arrangements) but again this would have a very small effect.

What has been used in the era of powered ships (and before) are "sea anchors" but they are difficult to get right. IF (????) Bismarck had experienced carpenters, sailmakers and bosuns then MAYBE they might get one made, but again with the seas running you get the same problem as with towing, the sea anchor and towing tackle would be put under immense strains as the ship moved in the heavy seas, any sort of canvas sea anchor is questionable (strength versus effect required) - an alternative would be the equivalent of a "barn door" - getting the strength and size right is almost impossible as is rigging.

..

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Re: bismark-after torpedo hit

Post by paul.mercer » Tue Apr 20, 2021 9:08 am

Gentlemen,
I think there is another point that has been overlooked regarding trying to rig up some sort of paravane/sea anchor, and that is the whole thing would have had to be done in the dark. The final torpedo attack did not occur until after 20.30 after which (according to the Baron's book), numerous attacks were made by destroyers during the night, so unless Bismarck was going to light up herself using floodlights and perhaps by using welding gear it would be very difficult for the men to see what they were doing and to add to the problem Bismarck's guns were also in action against the destroyers, so I'm sure the crew would not like to be on the fore or after deck when 15" guns were going off!

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Re: bismark-after torpedo hit

Post by wadinga » Tue Apr 20, 2021 10:29 am

Hello Paul,

It also mentions in the Baron's book that they tried to deploy a collision mat over a hole at the stern, so operating in the dark wasn't such a problem.

Creating sea anchors, drogues and all the other faff is experimental. The paravanes are available, deploying them and towing them is a standard operating procedure and there are plenty of bollards, fairleads and capstans strong enough to tow from.

Deploying them in the prevailing weather would not be easy, and how much towload would be available to counteract the rudder effect is questionable. We have documentation of 1-4 tons per unit.

All the best

wadinga
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pgollin
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Re: bismark-after torpedo hit

Post by pgollin » Tue Apr 20, 2021 11:21 am

.

A paravane is streamlined, which is not what is wanted. You need drag, which in those seas is a disaster for the towing rig.

.

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Re: bismark-after torpedo hit

Post by wadinga » Tue Apr 20, 2021 4:31 pm

Hello PGollin,

I think discussion of paravanes should be in the Raumotter thread.

As Marcelo has proved and supplied graphs show, paravanes provide plenty of drag, but delivered as beneficial horizontal lift, specifically because of their angle of attack they "fly" and produce force outwards from the hull, not merely backwards. Just hauling clutter through the water provides rearward drag but does not provide any force directly opposing the rudder action which is pushing the stern to starboard. Even towing a drogue from the end of the deployed port crane only gets rearward drag a few metres outboard and the tow point is over a hundred metres forward of where the rudder is exerting its turning force.

Ideally the paravanes would provide a force outwards at right angles to the hull, exerting 1-4 tons at each tow point on Bismarck's aft port quarter, pulling the stern to port. in practice they drop back somewhat, and the tow load is expressed at maybe 135 degrees from the bow. However the shorter the tow wire the less of it is dragged sideways through the water and the more energy from the paravane is delivered to the tow point in the right direction, ie nearly at right angles to ship's axis.

As you have observed yourself, paravanes are capable of operation up to the maximum speed of the ship, and the deployment of just two robs a battleship of 1-2 knots. How many thousand horsepower are deployed to get those 1-2 knots? They exert powerful forces.

All the best

wadinga
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hans zurbriggen
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Re: bismark-after torpedo hit

Post by hans zurbriggen » Wed Apr 21, 2021 7:07 am

Hello Mr.Mercer,
I am sure Lutjens and Lindemann (I would surely add H.Netzbandt, Lutjens' chief of staff, who had commanded Gneisenau and also many others on board) were experienced seamen, but 1) battleships captains are often selected between former "gunnery officers" (Lindemann was mainly a G.O.), more than based on their skill in maneuvering ships and 2) none of them was ever writing specific manuals on seamanship, like A-S-H.
Again, let's agree to disagree on his proposal (and also on Bismarck's fate being sealed no matter what), but I am sure A-S-H knew what he was speaking about, when proposing anchor with one cable length chain (that was capable of 100.000 tons force strain, thus no problem to support needed drag in any weather) as sufficient to stabilise course.

hans

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Re: bismark-after torpedo hit

Post by hans zurbriggen » Tue Apr 27, 2021 8:16 pm

Hello to all,
I come back to some critics to A-S-H proposal (http://www.kbismarck.com/bismarck-seemannschaft.html) on how to steer Bismarck sailing astern toward France after torpedo hit.
Mr.Jurens wrote: "Basically, if it could have been done, lengthy high-power astern work it would have been employed somewhere somehow on a fairly regular basis, or at least mentioned in various manuals of seamanship, etc., but it wasn't. Usually, these deal only with the loss of a rudder or propeller, and even then few seem to suggest that travelling astern for any distance or at any significant speed is something to even be considered in solving the problems. It was, more-or-less, always 'call a seagoing salvage tug' "
Mr.Wadinga wrote: "ships do not sail astern for any distance and almost always only at slow speed when manoeuvring in a sheltered harbour location " and "A S-H's study has some simple diagrams, but tellingly no real-world examples of ships sailing astern for lengthy periods even with fully operational steering gear. "
I have found this interesting picture: actually USN Ernest G. Small (3,000 tons and 118 meters long before bow collapse, 2 screws) sailed astern for long time, without assistance from tugs at meaningful speed, during Korea war to get back up to Japan.
Apparently USN ships don't have the tendency to turn stern into wind as German ships (mentioned by A-S-H and confirmed by Mr.Nilsson), not needing any anchor drag to keep a stable course downwind.

hans
Sailing Astern.jpg
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