Stern section of the Bismarck - question

[Tiornu]

No. Which problems? Which others?

[Dave Saxton]

Okay, I missunderstood the context of your comment. Is your comment in the context of US warships only, or also US commercial ships, and is it in the context of structrual design, and/or joint design, or welding execution? May I inquire to what the strong evidences against a systemic problem involving US hulls are?

[Bill Jurens]

This topic seems -- either intentionally or accidentally -- to have be been diverted from a discussion regarding the design of stern joints on Bismarck to some sort of general investigation into the performance of USN designed hulls in typhoons, etc. There is really very little relationship here, and I might point out that even in the best case, the promotion of what appears to be an 'my design was OK because everyone else had (similar?) problems, too' type of argument represents a very shaky justification indeed.

It would be helpful, I think, to put a few things in context here. The USN operated many thousands of warships during World War II, over probably billions of operating hours, sometimes in very heavy seas indeed. In such situations, occasional incidents of structural damage are not only to be expected, but can actually been seen as an artifact of GOOD design rather than bad. The designer must always balance structural considerations against probabilities and consequences. One could, for example, design a hull structure that was essentially impervious to sea-inflicted damage, but at what cost to payload and operational ability over the lifetime of the vessel? One could have put 6 inch thick pressure hulls on Gato class submarines and thereby undoubtedly have prevented some losses due to depth charge explosions, but at what cost to range, and weapons payload? At some point, diminishing returns and the requirement to accomodate conflicting requirements must be assessed and weighed using good engineering judgement. In most cases, USN engineering judgement appears to have been sound.

We must also keep in mind that a lot of incidents appear in the USN records simply because USN records were better-kept (or at least were stored in a manner more accessible to English-speaking readers in both primary and secondary sources). Further, because of the very large numbers of vessels in the fleet it might appear that more failures occurred there than elsewhere. The fact, for example, that 1,500,000 people in the US died from heart disease in 2004 as compared to only 500 in Monaco does not, however, mean that heart disease is more prevalent in the US. It just means that the US has a much higher population. We tend to have much better records concerning operational matters (and deficiencies) in the USN and the Royal Navy than elsewhere. This is largely because other records have been destroyed or have simply never been consulted by English-language readers.

The comments regarding the failures of wartime merchant hulls are interesting, but do not necessarily translate into any sort of meaningful comparisons with Bismarck. Lots of war-built merchant ships suffered various and sundry structural failures, but in the vast majority of these cases the failures were relatively minor. One must also note that many of these war-built 'victory ships' were built very rapidly using relatively unskilled workers, 'on the cheap' because it was not expected that they would survive very long. Quantity rather than quality was the issue here. (The fact that so many served for so long after the war indicates that their construction, in many cases, was really not that bad at all.)

This tradeoff of quality for quantity was not, or was probably not, the situation with pre-war built warships, especially major vessels such as Bismarck, which were, comparatively very important and very expensive vessels which should not have been built 'on the cheap' as well. Bismarck was a specialized vessel built in an extremely experienced and quite well-equipped shipyard. The 'victory ships' were, in comparison, the nautical equivalent of the jeep. Expendable.

Bill Jurens

[Tiornu]

"May I inquire to what the strong evidences against a systemic problem involving US hulls are?"
I was referring to George's citation of multiple ship-typhoon encounters with only a few examples of hull damage.

[Randy Stone]

...Bill.

I was thinking about operational hours, fleet size and other issues but then I reverted to my initial comment of "So what ?" regarding typhoon (not "...weather..." or "...storm...") damage.

Another point which dovetails nicely is the fact that the B-17 was designed with a life expectancy of 6 months...something to consider in conjunction with your 'jeep' comment.

It is without question that you put your finger on the issue by posting this comment: "...the promotion of what appears to be an 'my design was OK because everyone else had (similar?) problems, too' type of argument represents a very shaky justification indeed."

But it is, at least, an indication as to how the argument that 'my design was superior in all respects' has fallen on some rather hard times when one writes, 'Well, so did yours !'

We've had a number of succint, eloquent and humorous posts on this thread -- your latest post is one of them.

Randy

[Dave Saxton]

I wouldn't mind a more general discussion of warship welding, circa WWII, not necassarly centered around the Bismarck's stern. It's such a lightning rod for pointless argument. There are many aspects and systemic problems to warship welding, worldwide, during this period, that are not well understood today. I think a broader discussion of welding problems of WWII would be more fruitfull, or at least more interesting at this point. What more can we determine about one ship's severed stern without more detailed data? We can't really determine with a degree of certianty whether the weld execution was bad or good. Any firm conclusions as to the execution would be premature at this point, in my opinion. There are so many factors to consider, but no specific data on these meriad individual factors. Additionally we still don't know enough about the rationals behind the joint design at this point. I have been about as critical of that specific joint design, based on what data I have so far, as anybody. It's much more complicated than simply joining a prefabbed section on the end, to be fair.

Were the welding practices used by B&V also used by other shipyards, worldwide, in the construction of major warships, during this period? The answer is yes. Would some of the same failure modes have manifested themselves had other capital ships been exposed to the same abuse? Probably. But we will never know for sure.

[George Elder]

Hi Bill:

The point is, you used the word "sophmoric" to describe German welding practices, and I thought that most inappropriate given the general state of welding at the time. And now we give you example after example of where US welds and structures failed due to stress of weather, and you say this is off point -- or that the US simply kept better records, etc. etc.. Well, I don't think a dispassionate reviewer will thinks so. The examples simply point out that the problems the Germans faced could be considered an endemic rather than unique.
Furthermore, I believe you will find there is example after example of welding problems with US warships beofre they even left the builder's yards. And please -- don't give me this argument that "the US simply kept better records." I don't know many organization who kept better records than the Germans, and although much was lost -- I suspect there is a lot more that we simply have failed to bring to light, both pro and con.
As for generalized welding problems within the US navy, I suggest that if we look they will be found -- and these weather-related examples are but the tip of the iceburg. Yet even when this data is unearthed, should I then make the provokative claim that US welding was amaturish or sophmoric or inept? No, I don't think so. I think the US did the best it could with the technology as it was understood at the time. I see no evidence whatsoever, that the US employed a better or worse approach to welding than did the British, Germans, etc., and if you have data to the contrary -- then by all means please present it for consideration.
Overall, there is a tendency to do a lot of bashing when the subject of the Bismarck comes up. On one hand, we see the real and imagined flaws of the Bismarck carted out with glee by what I would call hardly call objective reviewers. These same people extrol ships such as the Iowa as the highest example of the battleship building art, and simply make excuses for any warts that are pointed out. What I truely do not understand is why this should be the case? That is a moral issue, and perhaps one we cannot consider here.
And I should not go on concering what I consider a "rah rah" tendency because poor Richard has serious problems with sermons -- although it is nice that he found some to rejoin us. And it is Sunday, so perhaps a sermon can be forgiven. Well, this has been fun, but it seems like the lesson that all navies had problems with welding may have been lost.

George

[Bill Jurens]

I think that the problem revolving around differences in record keeping and record survival is a real one. It's likely, for example, that Japanese shipbuilders experienced welding failures too, but it's unlikely that many of the records of those failures now survives or is reasonably accessible to English speaking (and North American based) scholars. It would be wrong, however, to conclude from this that the Americans for example, suffered many more welding failures on a per-capita basis than the Japanese. Because they lost a rather protracted and ugly struggle, it is only to be expected that German records would be less complete than Allied ones, if only because many of the really valuable sources, if they survived, were simply looted by the allies after the war ended. And, because few of us are fluent in German and close to German archival sources, it is much more difficult for us to access such information in the first place.

You will note that I described the weld design itself as 'sophmoric', not necessarily the execution. I have no real information at hand regarding the quality of the weld itself. I quite deliberately had the ROV on the 2001 expedition zoom right in on the welded failure line so that somebody in the future might be able to glean more detail on the exact cause of the failure, but these tapes are not readily available. Sadly, from a forensic viewpoint, there's a lot of corrosion involved, and it's likely in any case that the detail required has long since corroded away.

I can tell you that any substantive 'unzipping' failure of a weld, without distortion and/or involvment of nearby structural members (unless for some reason deliberately planned by the designers) represents a prima-facae case of poor design, this failure being independent of the quality of the weld. The shell and the associated stringers etc. are supposed to work together to support loads, not separately. It should be noted that the stern weld on Bismarck was not the only area to exhibit inept weld design; the superstructure joints were also very poorly designed and executed, even considering the technology of the time. We do sometimes use similar techniques in modular construction today, but we know an awful lot more about welding now.

Bill Jurens

[Dave Saxton]

Some of the problems shared by those who began to replace riveting with welding for warship construction during this period are:

*Joint design. Engineers still had an affection for overlap joints during this period, indicating a lack in faith of butt welds. This led to the overuse of weaker fillet welds, and hybrid designs. It was common wisdom that the least welding is the best welding. I have a series of construction photos of battleship Jean Bart. In one photo they show them constructing a double bottom section. They are using single pass fillet welds no more than three or four inches long. Not very stout.

* Skilled workmen, who were in powerful unions, were set in their ways, and job scared. Platers, loftsmen and other skilled laborers were used to dealing with lap joints required for riveted work. Welded work requires very exact dimemsions and accurate fit up. Poor fit up results in poor quality welding, regardless of the skill of the welders, or the joint design. Platers, ship fitters, loftsmen..ect.. didn't have the training in higher mathmatics to provide the accuracy in dimension and fit up required for welded construction. Modular construction is even more demanding in this regard.

*Poor oversite and leadership. Quality welding requires executive oversite, on the site. There was a worldwide dearth of individuals who had both the higher education, and the hands on experiance in the welding arts required. IIRC, of some 28 US yards only 4 had designated weld engineers on site. Of those only two had 4 year University level education, and these were not in the technical areas specific to welding.

*Poor Weldabilty of the materials. Ducol was found to be of poor weldabilty. Many weld failures can be found among those that used D steel as their construction steel. DW had to be devoloped before welding could be used more extensively. I also have a US BuShips document from 1943 that mandates a change in composition of American HTS to improve weldabity, and reduce weld failures. Vanadium use complicates this general problem, as vanadium alloys are hyper sensitive to hydrogen ions and heat cylcling. The Germans were ahead of the curve when it comes to the factor of weldabilty, and their ST52 had been the material of choice in post war welded ship building.

* Hydrogen embrittlement. This is the major cause of cracked welds, and fractures. This is the biggy. This is a Collory to the the problem of weldabity of materials. Many materials, particulary high strength low alloy steels, such as D steel, ST52, HTS and armour plating are very sensitive to hydrogen ions. It is now generally accepted that the Liberty ship failures was a combonation of brittle constuction steels and hydrogen embrittlement. In British documents The British don't seem to a have clue about this by 1943. 1944 German engineering articles are highly critical of the continued use of cellulose covered electrodes by the Allies. Yet the American and British shipyards seem fully aware by late 1945. They may have learned this from the Germans after VE day, or they may have discovered this on their own. The Germans had reasearch data on hydrogen embrittlement as early as 1931. However, lab research and actual application in the field are two different things. Preheating is a common strategy to reduce the effects of hydrogen on the heat effected zone. Using austenic stainless steels such as 307, 309, 310 had the defacto result in reducing the effect though. Austenic micro structures don't allow hydrogen ions to embrittle the matrix.

*Welding involves heat cycling and different materials react differently to heat cycling. Improper heat cycling results in adverse changes to the micro structure of the steel.

* As a collory to the above is residual stress and welding distortion of the plates. Residual stress can be a serious problem were the materials lack ductility. Distortion is always a problem and greatly complicate proper fit up, and can curtail good excution of welds. It has been shown to a major problem involving automatic welding in Japanese shipyards more recently.

* Chromuim dilution of the weld metal when, automatic welding in particular, was used on dissimilar metals welded joints. This was a factor involving the American 310 and 309 stainless steel. I personally feel this was major factor in the Bismarck stern detatchment.

* As a collory to the above was the potential for micro cracks when using fully austenic weld metals, lacking in ferrite content. I believe this was one of the problems unccountered by the Italians, that made construction of their TDS systems less effective. The American 310 weld metal has shown a potential to crack during high speed shock loading in modern reseach. There are secondary writings alluding to this involving BB55's torpedoing. I was unable to locate the actual repair records in Maryland last summer though, if they exist.

* Corrosion. This was a factor effecting everybody, and the heat effected zones of welded plates are particularly vulnerable. Also seawater can sometimes leach the alloy content of alloy containing metals adversly.

[Javier L.]

This is about bows. I watched Cameron's documentary again and noticed that the Bismarck hit the ocean floor with her bow first. Question is: what was the approximate speed of the hull when it collided with the ocean floor? I think this is important to know because it is remarkable to see that the bow didn't break away from the main hull after all of the stress the hull went through during the sinking process. How can we explain the fact that the welding-joints worked so good in the bow section and "not that good" in the stern?

Some of you have attributed the fact that the bows/sterns of warships usually break away bacause, among other causes, failures in the discontinuities between the main citadel and the ship ends. However I notice that in Bismarck case the bow is reinforced with 60 mm side splinter belts where other warships did not have anything at all. This might explain why the bow is still attached to the main hull. The splinter belt aft however ends exactly in the frame where the stern broke away (discontinuity problem?).

In my opinion the Bismarck had a formidable structural strength far superior to other warships of her kind in many aspects. The fact that 10 meters of stern broke away 14 hours after it was torpedoed is not cause enough to say the design was poor. What would be the effects of a torpedo hit in the unprotected stern of any other battleship?

Finally, this is perhaps not comparable with Bismarck's case, but look at the damaged bow of the Washington (BB-56) after the collision with the Indiana (BB 58) in 1944.

http://www.usswashington.com/collapse.jpg

http://www.usswashington.com/collis_2.jpg

Javier

[Ulrich Rudofsky]

http://id.mind.net/~zona/mstm/physics/m ... tion1.html

I think the speed of hitting the ocean bottom is considered to be 20 mph, although I may be wrong. The Bismarck was not built for that. You have to consider the laws of physics. No ship is built to make that kind of dive. The whole dispute about German and anyone's warship tail ends seems weird. Most things in life are built not to be perfect, but to make an intelligent compromise between very well known factors and possible conditions to be encountered. In that sense, the Bismarck was well built.

[Bill Jurens]

Dave Saxton has, I think, done an excellent job in summarizing the situation just prior to and during the war. I've seen no better nor more accurate summary anywhere.

To Javier and Ulrich:

The impact speed is indeed taken to be about 20 mph, but as studies of sinking objects (albeit much smaller than battleships) seem to indicate, the path on the way down can be somewhat cyclical and it is difficult or impossible at this stage to determine exactly at which stage in the cycle Bismarck may have encountered the seabed. Also, the amount of clay cover over bedrock varies quite a bit from place to place on the site, and it's difficult to determine how much silt Bismarck's hull encountered before striking bedrock, if it ever struck bedrock at all.

My examination of the Cameron tapes, which were much clearer than the tapes we were able to make in 2001, indicated rather severe buckling in the weather decks forward, coupled with some misalignment of the strakes of armor plating etc. further down in the hull, i.e. in the sheer strakes and below. Considering the situation, i.e. a collision with the bottom, this would indicate that the bow structure performed more than adequately. There is no implosion damage forward, indicating that the hull was in a free-flooding situation when the ship left the surface.

I am speculating here, but I believe that due to restrictions on slipway length, Bismarck's bow was probably manufactured 'on site' i.e. directly on the ways, and was not 'stuck on' to the hull in a modular section at all, but that the stern, which might have overhung into the river etc., was probably assembled as a modular unit, being attached in one big piece. This would explain the unusual failure at the stern, whilst the bow remained intact.

Rather than being heavily built, it's been my general impression whilst going over various drawings and after many hours of inspecting the wreck in person that Bismarck was, overall, rather 'lightly' constructed compared to her contemporaries. In that regard, there may indeed be a parallel between Bismarck and the Brooklyn class light cruisers of the USN mentioned earlier in this thread, insofar as both designs appear to be a little on the 'flimsy' side overall.

Bill Jurens.

[George Elder]

Bill:

You are the only writer I know who has ever claimed that the Bismarck was lightly built, and then gone on to make a comparision with the Brooklyn. And while I have come to expect such hyperbole from some corners, it is disheartening to hear it from you. In what sense is the Bismarck lightly built? Give me an example as it relates to frame dimensions, spacing, etc.. Then compare these data with the Brooklyn. Do you realley think your credibility will benefit from that exercise? Furthermore, how can you claim the aft section was not designed to work with the stringers, etc. when you lack the framing plans of this section? This is exactly what I mean by overstating a case. And if it takes you a week or two of Sundays to find specifics, then so be it.
As for now, I cannot take your words with any serious intent. I respect scholarship, but do not see a lot of that here -- except for Dave's work. He does the serious digging, and presents things in a dispassionate and academic fashion. Bill, I cannot regard your recent efforts is being at all in the same ball park.
Ultimately, this thread has certainly presented enough material to let any party make his/her own decisions regarding the application of "sophmoric" terminologies, evidence of bias, and what authors are or are not credible.

George

[Patrick McWilliams]

I must agree with you George. It's laughable to suggest that Bismarck was lightly built. She was able to sail close to 1,400 miles after receiving three 14" hits and Prince of Wales would have been sunk if one of Bismarck's 15" shells that penetrated the bow or bridge had exploded. So much for a lightly-built battleship (surely a contrdiction in terms).

Bill is an experienced poster and has added a lot to our enjoyment of the site but on this occasion I'm not sure that he envisaged the mirth his choice of words would create.

Patrick

[Bill Jurens]

Regarding Bismarck's construction, I can assure readers that no mirth or sarcasm, etc. was intended. I have been fortunate to have been able to visit and tour virtually all of the battleships still extant, have viewed a very large number of drawings of Bismarck and have also been extremely fortunate in being one of those few individuals to have been able to examine the wreck of Bismarck in detail as well. And, of course, I've seen a lot of other old warships as well, e.g. some of the wrecks at Jutland. And, I've read and studied most or all of the information available from the U.S. Naval Technical Mission to Europe, that addressed structural considerations in detail.

My general impression, again, based on all of these observations, is that Bismarck was indeed somewhat more lightly constructed than average for her type. This is not necessarily bad; one might even say that all things being equal, a lighter construction is more efficient and therefore better. In that regard, Bismarck might actually be seen as a sort of 'Brooklyn class battleship', as the Brooklyns were a bit on the light side for their class, i.e. compared with other light cruisers, Bismarck might be seen to be, structurally a bit on the light side for her class, i.e. compared with other contemporary battleships.

I honestly don't have any biases here, and no axes to grind. I'm just sharing my observations to those who might be interested to read and learn from them. Those who disagree are entitled to their opinions, however derived.

I regret that I simply don't have the time, however, to get bogged down in endless discussions regarding details, particularly those delivered in an argumentative and derisive tone.

Bill Jurens