bismark-after torpedo hit

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wadinga
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Re: bismark-after torpedo hit

Post by wadinga » Mon Mar 29, 2021 10:34 am

Hello Hans,

Struggling as I am with an internet translation of A S-H's article it would help if you can clarify a few points and confirm whether I understand his points correctly.

His Hessen example refers to trials with a much shorter, smaller 3 shaft ship with a single central rudder. He compares length/beam ratio but fails (I believe) to compare the lever arms of the two ship's outer screws where Hessen's are farther apart relative to her length than Bismarck's. He seems to indicate that running the centre screw in reverse in Hessen effectively disables the rudder effect and the vessel can be steered with the outer screws. I am unclear whether this is with the rudder only in the fore and aft condition or whether the centre screw would overcome the effect of a rudder over at say 15 degrees. He then goes on to point out that this example is completely different to Bismarck's installation. I believe he says of Bismarck "nothing is known of such trials". However we believe that during Bismarck's trials attempts were made to steer with engines alone, presumably with rudders in the fore and aft position ie not exerting any deleterious effect, and yet was impossible to steer the ship. No mention is made of weather conditions during either set of these trials but I suspect they were nothing like those out in the Atlantic at the time in question.

Then there is a comment about dragging an anchorless chain from the bow when leaving port, apparently going astern. 25m of chain are mentioned, by which I assume given shallow water a considerable length is dragging along the seabed, which would indeed be an extremely powerful heading stabiliser, since as we have established, ships do not steer well going astern. However for the water depth in which Bismarck was operating there was no possibility of dragging on the seabed, so I do not see the applicability of this technique. Maybe he is just suggesting that dangling a bow chain would act as a drogue, through water drag, but whether this could counteract the very powerful port turn effect of the jammed rudder when going astern is to my mind pure speculation. He also seems to make no mention of windage on the hull which would tend to make the ship swing round until beam-on.

His lack of consideration to prevailing weather conditions on his tentative proposal steering Bismarck astern becomes very confusing when he describes the constraints caused to the shadowing destroyers by the wild conditions that night.

If I have gathered this gentlemen's points correctly, I do not believe they are very applicable at all, and the Baron's dismissal of them seems fully justified. If the ship could not be steered with engines going forward in the calm low wind conditions of the Baltic, there is little reason to practice or trial going in reverse in bad weather on the assumption that such a situation would somehow make things better. I, like you do not understand the Baron's observations which ignore the fully operational gyrocompasses etc. I consider that since there is no sensible argument to be made against such fanciful speculations, which could never be trialled, he felt he needed to come up with some reasons of his own. There are no real-world precedents for A S-H speculative techniques which are just thought experiments extrapolated from very shaky foundations IMHO. Thus I do not see him providing any valid evidence at all about ships with a jammed rudder at 12/15 degrees travelling astern in very bad weather.

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wadinga
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Re: bismark-after torpedo hit

Post by gcogger » Mon Mar 29, 2021 7:31 pm

paul.mercer wrote:
Mon Mar 29, 2021 9:35 am
What does puzzle me is that Rodney was apparently loaded with spares and on her way to the USA for refit, which would suggest that she had enough fuel for the Atlantic crossing, so why did she run short - even though she was originally sent in the wrong direction during the hunt?
I imagine that the sustained full speed run to try and intercept Bismarck would have used considerably more fuel than her originally planned voyage.

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Re: bismark-after torpedo hit

Post by wadinga » Mon Mar 29, 2021 9:22 pm

Hello All,

I believe it was only KG V which was running short. With her paltry powerplant and hence meagre consumption Rodney could have kept going.

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Re: bismark-after torpedo hit

Post by gcogger » Mon Mar 29, 2021 11:36 pm

On the HMS Rodney fuel situation, there are a number of excerpts from the timeline of events here: https://www.naval-history.net/xGM-Chron ... Rodney.htm

(26th) At 1821 hours the CinC signalled the Admiralty and the CinC Force H; unless BISMARCK’s speed had been reduced by midnight he would have to return to harbour for lack of fuel; RODNEY could continue until 0800/27
(27th) At 1014 hours RODNEY ceased fire and withdrew in company with KING GEORGE V to the north east both battleships were dangerously low on fuel.
29th – At 0300 hours RODNEY with heavy cruiser NORFOLK and destroyers MAORI, SIKH, LEGION and COLUMBIA arrived off Greenock. RODNEY’s fuel tanks were virtually empty and she immediately commenced bunkering and replenishing her ammunition and other stores.

I'm not sure how accurate the above is, but it does suggest that Rodney was not as low on fuel as KGV. Refuelling at Greenock would, of course, have happened regardless of the state of her fuel tanks.

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Re: bismark-after torpedo hit

Post by hans zurbriggen » Tue Mar 30, 2021 7:14 am

Hello Mr.Wadinga,
I am afraid I do not have the English and seamanship skills (time too) for understanding 100% and to translate correctly this article.
Hessen tests were done with blocked rudder at an angle (thus necessity to run center screw astern).
The difference of the single vs twin rudder is treated by Schultze-Hinrichs who points out that central screw (a left hand screw for Bismarck) could compensate the lesser effect of its ahead flow against twin rudders. A-S-H says that Bismarck dimensions/configuration should have worked: Hessen was smaller ship but I don't know the distance of the outer shafts nor their convergence, that are key data more then dimensions."Lever arms" and "rotation center" considerations are too technical for me to challenge them: I rely on A-S-H as an expert.
I am not sure whether Bismarck was still a (15° to port) blocked twin rudders ship (H.Kuhnt account), or possibly she was already a blocked-single-rudder ship (starboard rudder bent to port behind the center propeller and port rudder gone). In second case she was similar to Hessen.
A-S-H proposes to have an anchor with 25 meters chain (not only the chain as in harbour situation) dropped at the bow to drag into the water and stabilise the course. Also other solutions are proposed to help steering during the astern motion (
http://www.kbismarck.com/bismarck-seemannschaft.html)
I think his theory is very well detailed/studied and could possibly have worked, but we will never know.

Hello Mr.Mercer,
I respectfully do not agree that the ultimate fate of Bismarck was already sealed, had this theory proved right. After having received the torpedo hit, Bismarck had just 100-150 sea miles to go South-East to reach safety under the range of the Luftwaffe. During the night the Ark Royal could not launch any strike. There could have been another attack in the morning, if Bismarck was still located (A-S-H opinion is that Bismarck could have slipped away running astern). Then once Bismarck was under Luftwaffe protection, the carrier airplanes could not reasonably harm her anymore and all ships (carrier included) would have had to step back (or suffer heavy losses, had Admiralty insisted to continue "up to the Shores of France") even with a less critical fuel situation. Bismarck could then have been towed by tugs in harbor.

hans

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Re: bismark-after torpedo hit

Post by paul.mercer » Tue Mar 30, 2021 8:20 am

Hi Hans,
Thanks for your replies, I'm afraid we will have to agree to disagree on this one as the bulk of opinion seems to be that all the alternatives were either not practical or almost impossible to do in the prevailing weather conditions and trying to get 150 miles by going astern in bad weather is going to take a very long time - too long in my opinion. As I have already said, once Bismarck had been located by aircraft the RN were never going to let her get away, even Rodney at her slowest speed could have caught up with her and even if KGV had to withdraw through lack of fuel could have battered her into a wreck on her own.

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Re: bismark-after torpedo hit

Post by wadinga » Tue Mar 30, 2021 10:07 pm

Hello Hans and all,

Ploughing through Kpt zS Alfred Schulze-Hinrich's article his revolutionary, and arguably controversial concept seems to be to exploit the difference between the pivot point of a ship going forwards and the pivot point going astern.

Ships going forwards steer somewhat like a car in reverse, the stern slides over to port as a result of the rudder(s) diverting water thrust to starboard, which results in pushing the bow and therefore the ship's heading to starboard. This is necessary to overcome the hydrodynamic stability of the long narrow hull which tends to keep going in a straight line and which becomes stronger the higher the speed. Short dumpier hulls, like Hessen's, are easier to turn than longer hulls, and Bismarck is twice as long as Hessen. During a hard turn a slick is produced next to the hull on the inside of the turn as water flows under the hull and "boils up" at the surface. The point within the hull where the ship appears to pivot around is often described as being one sixth back from the bow. A S-H depicts Bismarck's pivot D as being slightly further aft.

When going astern, there is a complex combination of less effective propeller thrust, since the blade shape is optimised for one direction only (forward) and the deflection of their reduced thrust is against the hull instead of into clear water, but also with the rudder encountering undisturbed water as the vessel moves astern it exerts a strong effect and gives a more rapid turning effect. The pivot point D' moves aft a very long way as A S-H depicts. Starting from a standstill there is little hydrodynamic heading stability and the stern can be moved almost laterally right or left especially if the rotational direction of the prop(s) exert a paddle wheel effect. However, once the vessel gets moving astern the hull hydrodynamic starts to stabilise heading somewhat.

All of this completely ignores wind effects. Operating astern at low speed, say when manoeuvring in a sheltered harbour, the wind would tend to blow the bow round and the ship ends up stern to wind.

It seems, if I understand him correctly, that A S-H assumes that the deleterious effects of Bismarck's jammed rudder can be neutralised by use of the centre propeller acting against it. (The crew have to psychically know the bent rudder is somewhere near the centre propeller, somehow.) However as I understand it his Hessen Effect, as described, works when going ahead and there is no actual example of it working when going astern. Presumably the centre screw has to be driven for forward movement so as to neutralise water flow over the rudder, whilst the two outer props go powerfully astern, adjusting their revolutions to achieve some steering control. He considers the closeness of the pivot point to the props and rudders would help with this. I think even he suspects the steering ability would actually be fairly minimal, hence dangling an anchor off the bow and I think he mentions trailing a hemp hawser as a drogue too. These are traditionally small ship/yacht techniques and I don't think there are any examples for large, say 50,000 ton ships. We are surely only talking about a few tons of drag, whereas the power of waves and wind pushing the bow round one way or the other would be many tens of tons.

However, Bismarck is not manoeuvring in a sheltered harbour, but in near Gale force winds where even A S-H notes the destroyers have to reduce speed. There is something about comparing Bismarck's imagined speed astern as compared with wave travel going past her, but surely swells striking her, unless she managed to lie exactly bow to weather, would throw the bow off to one side or the other and windage would push her round beyond the very limited steering capability to hold her on course, IMHO. I fully respect Kpt zS Alfred Schulze-Hinrichs' arguments and his experience, but cannot agree that these techniques would work at all. It would be interesting to know if his suggestions were positively received when published, unlike the Baron's response.

I believe his cheeky suggestion that because Bismarck would be pointing NW but she would be proceeding SE she would inevitably lose her shadowers as risible as you have found the Baron's navigational observations. :cool: He is also wrong about it being unlikely Ark Royal could launch another strike, due to the weather. Despite the wind being so strong the deck handlers had to hold the aircraft down to stop them sliding sideways off the deck as the carrier turned into wind, the Swordfish could operate in these wild conditions. A strike was airborne and ready to put more tinfish into Bismarck, but Tovey refused to give them a chance and gave his gunners a free hand.

Even if Bismarck had managed to reach extreme range of the Luftwaffe assistance, the aircraft would have little time on target, before they had return home.

I spent over a dozen years working at sea in the seismic survey business, towing arrays of equipment to create images of subsurface geology so I have seen good and bad ship handling in all kinds of weather first hand.

All the best

wadinga
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Re: bismark-after torpedo hit

Post by hans zurbriggen » Wed Mar 31, 2021 8:03 am

Hello Paul,
yes, let's agree to disagree: IMHO fate of Bismarck was sealed by the single torpedo that blocked the rudders, not by having been merely located by airplanes.

Hello Wadinga,
thanks for explaining A-S-H theory re. pivoting points etc. (still I miss the needed technical knowledge to challenge it).
I think we will have to agree to disagree on your conclusions: A-S-H was a full Captain in Kriegsmarine, expert in handling large ships (not yacht in harbor) and his theory cannot be dismissed: it could only have been proven wrong by running engines astern, that was never done on Bismarck. When article was written, no evaluation of actual damage to Bismarck rudder(s) was available: the theory is based on twin rudders in place and turned to port 15°. The single bent rudder should have even worked in favour of A-S-H theory (center propeller could nullify rudder, Hessen method).
Re. Bismarck slipping away, it's not easy to keep touch in dark night in gale, especially if your reports say Bismarck is heading NW (while she is actually going SE). In the morning of May 27, no ship was in view and it took some time to Norfolk to locate Bismarck. All others had lost touch and came later.
In the morning only, Ark Royal could have send recognition Swordfish to re-locate Bismarck and only then launch armed planes to further try to torpedo her (how many small torpedo hits could Bismarck still withstand ?)
At dawn Bismarck would have been 70-90 sea miles closer to France (and 7-9 sm more each hour). Luftwaffe could have mobilized any plane to provide air cover (few minutes each plane, true, but how many planes were available in France and how much superior to the Swordfish were the German hunters ?). Whether Luftwaffe would have done this at any cost, is a question mark, in view of rivalry with Kriegsmarine.
Would Tovey have obeyed Admiralty orders or would have he retired (as he declared he was ready to do in case Bismarck was too close to France) ? Too many open questions I think to get to single answer.

hans

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Re: bismark-after torpedo hit

Post by RF » Wed Mar 31, 2021 6:13 pm

hans zurbriggen wrote:
Wed Mar 31, 2021 8:03 am
Hello Paul,
yes, let's agree to disagree: IMHO fate of Bismarck was sealed by the single torpedo that blocked the rudders, not by having been merely located by airplanes.
I think this statement does need some qualification. What doomed Bismarck was the lack of any effective support or back up in the event of the ship being crippled, just as the AGS was lost because there was no effective backup to extricate the ship once it was damaged in battle, and that is before it bottled itself up in a hostile neutral port.

Had the KM properly invested in the planned long range Atlantic destroyers, had they been available in strength from 1940 onwards it could have been a very different story, particulary also if Graf Zeppelin was also operational and able to operate with those destroyers as escorts.....

This rather more than fanciful conjecture, had the Fuhrer the naval savvy to order Raeder to adopt the Y Plan from 1937 onwards instead of the Z Plan in 1939 then such a force could have been available, especially as the Y Plan was compliant with the Anglo-German naval agreement of 1934.
''Give me a Ping and one Ping only'' - Sean Connery.

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Re: bismark-after torpedo hit

Post by dunmunro » Thu Apr 01, 2021 4:42 am

RN Fuel State.

At Noon on 26 May KGV had 32% fuel remaining = ~1200 tons (Naval Staff History)

Signal from Rodney to KGV:
RODNEY (visual) to CinC H.F. 1911/26

Your 1829-RODNEY had 1600 tons of oil on
hand at 1800. We use at present speed 23 tons
per hour and 19 tons per hour at 20 knots. Clyde
and Gibraltar are within my endurance if present
course and speed are continued until 0800
tomorrow. (from Wellings)

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Re: bismark-after torpedo hit

Post by paul.mercer » Thu Apr 01, 2021 9:53 am

RF wrote:
Wed Mar 31, 2021 6:13 pm
hans zurbriggen wrote:
Wed Mar 31, 2021 8:03 am
Hello Paul,
yes, let's agree to disagree: IMHO fate of Bismarck was sealed by the single torpedo that blocked the rudders, not by having been merely located by airplanes.
I think this statement does need some qualification. What doomed Bismarck was the lack of any effective support or back up in the event of the ship being crippled, just as the AGS was lost because there was no effective backup to extricate the ship once it was damaged in battle, and that is before it bottled itself up in a hostile neutral port.

Had the KM properly invested in the planned long range Atlantic destroyers, had they been available in strength from 1940 onwards it could have been a very different story, particulary also if Graf Zeppelin was also operational and able to operate with those destroyers as escorts.....

This rather more than fanciful conjecture, had the Fuhrer the naval savvy to order Raeder to adopt the Y Plan from 1937 onwards instead of the Z Plan in 1939 then such a force could have been available, especially as the Y Plan was compliant with the Anglo-German naval agreement of 1934.
Hi RF,
You are absolutely correct on this point, the problem was that unlike the RN, once the German ships were far from home they had no safe haven to run to without risking internment which is why they were told not to engage with enemy capital ships in case they got severely damaged and refused combat with two ships that they should have been able to defeat (an unmodified QE and an R class) Rodney of course was an entirely different proposition! Both Hitler,and Raeder knew that they were vastly outmatched by the RN both in ships and building capacity so had to be very careful where and when their capital ships were sent out.
I'm not sure whether investment in long range destroyers would have made much difference in the Bismarck case even if they had been able to operate in the prevailing wind and sea conditions, once she was crippled it was only a matter of time before the long range aircraft found her and the RN did the rest. When Scharnhorst made he last voyage the escort destroyers had to turn back because of the weather so it is doubtful that even if some had accompanied Bismarck that they would have been able to keep up. As for having Graf Zeppelin available, this could have been very dangerous to the convoys initially, but probably not as effective as the U boats, but even then I think she would have had a relatively short life until the superior numbers of RN ships caught up with her.

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Re: bismark-after torpedo hit

Post by wadinga » Thu Apr 01, 2021 5:00 pm

Hello Hans and all,

We may indeed have to differ about the potential efficacy of the "might have been" technique A S-H proposed, but can we just clarify one thing from his article: did he mention the Hessen actually using this technique to travel astern at all? From my limited translation ability it seems it was only tried moving forwards.

This worthy gentleman was an expert in seamanship, co-authoring a book on the subject in 1940. However it should be noted he was a dyed-in-the-wool destroyer man, commanding the Erich Koellner, sunk at Narvik, and flying his flag in the Hermann Schoemann, scuttled after severe damage in the Barents Sea in 1942. He continued with the Bundesmarine after the war, but he may have had limited, if any, experience with such large vessels as Bismarck. Marine-Offizier-Vereinigung published 1st June 1967 is the journal he put his article in, and it would be interesting to know whether other fellow professionals commented on it.

I personally rate the opinion of one professional German naval officer, who unlike most other commentators, was actually there, Baron Mullenheim-Rechberg, above all others. Gerhard Junack, another survivor, came up with his own ideas, but the Baron dismisses them as even less feasible than A S-H's. In the concluding chapter of the revised version of his book, he considers all these proposals and concludes all that could be done was done, and that morale onboard remained high.
"Everything that could be responsibly undertaken, everything sensible, was tried." p443
PS Embarrassingly I made my own April Fool earlier in the thread. :oops: The rudder jam caused a turn to port, therefore the balancing wind and weather needed to act on the port bow to make the fine balance and allow the only reasonably stable course to be steered NW.

All the best

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Re: bismark-after torpedo hit

Post by RF » Thu Apr 01, 2021 6:11 pm

paul.mercer wrote:
Thu Apr 01, 2021 9:53 am


Hi RF,
You are absolutely correct on this point, the problem was that unlike the RN, once the German ships were far from home they had no safe haven to run to without risking internment which is why they were told not to engage with enemy capital ships in case they got severely damaged and refused combat with two ships that they should have been able to defeat (an unmodified QE and an R class) Rodney of course was an entirely different proposition! Both Hitler,and Raeder knew that they were vastly outmatched by the RN both in ships and building capacity so had to be very careful where and when their capital ships were sent out.
I'm not sure whether investment in long range destroyers would have made much difference in the Bismarck case even if they had been able to operate in the prevailing wind and sea conditions, once she was crippled it was only a matter of time before the long range aircraft found her and the RN did the rest. When Scharnhorst made he last voyage the escort destroyers had to turn back because of the weather so it is doubtful that even if some had accompanied Bismarck that they would have been able to keep up. As for having Graf Zeppelin available, this could have been very dangerous to the convoys initially, but probably not as effective as the U boats, but even then I think she would have had a relatively short life until the superior numbers of RN ships caught up with her.
The essence of my post was of the KM ships being able to co-ordinate more rather than operating entirely alone. You mention Scharnhorst, the five Narvik class destroyers under Johannson were actually ordered by Bey to fan out in a search for the convoy Bey was seeking, they were not ordered back home until some time later, indeed one of the destroyers saw the some ships on the edge of the convoy but was unable in the darkness to properly identify that the ships were enemy. Scharnhorst was ambushed twice, the second time by RN/Norwegian destroyers because its radar was smashed as battle damage, had Johannson stayed in close consort the Allied destroyers would have been detected before getting into lethal torpedo range.

The best way I think to demonstrate my point would be a game of chess, in which the KM has only one piece, a Queen, whilst the opponent has a full force of pawns, bishops, knights and rooks etc and even without an opposition Queen the KM piece would quickly be captured because the opposition pieces would cover each other and strip the KM queen of any safe movement.

If a few KM ships could cover each other the dynamic starts to change - Lutjens first problem were the shadowing cruisers, if he had more forces around the shadowing cruisers could be destroyed and then once free remain in mid-ocean using the supply ships while the RN battleships shorter endurance forces them back to port.
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Re: bismark-after torpedo hit

Post by hans zurbriggen » Fri Apr 02, 2021 8:03 am

Hello RF,
I totally agree with your observations: Strategically, Bismarck was a lonely queen against a full chessboard of enemy pieces.
Tactical question is whether Bismarck on 27 would have been lost anyway even without the torpedo that hit the rudders on 26: here I don't think her fate was sealed, in view of the poor endurance of British units and of presence of Luftwaffe in France.

Hello Wadinga,
Hessen method is mentioned because it shows how to nullify rudder action with reverse usage of center propeller. Hessen tests were done moving ahead. The core of A-S-H theory is the change of the geometry when in reverse motion for a ship like Bismarck, that would make easier to maintain course using outer propellers (converging shafts and forces with better lever arms). This, combined with Hessen method used in astern motion (center propeller to nullify rudder(s)), should have given Bismarck a chance (just a possibility, as per A-S-H himself).

hans

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Re: bismark-after torpedo hit

Post by paul.mercer » Fri Apr 02, 2021 8:14 am

Thanks RF,
I do see the point you are making.

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