Something is right with our bloody ships today

[Coypus]

Besides making capsizing less likely, what is the advantage to a high(er) metacentric height? Will it reduce rolling motion? Can the ship sustain harder turns? Are there any other practical benefits?

Lower silhouette, and a stable platform in calm seas if you have ever sailed a Laser in 15 Knts+ on a run that will give a good demonstration of what a high metacentric height feels like in a swell. For turning it was not great in high powered vessels as opposed to a low height like our friend the Invincible which could turn on a sixpence (A good example if you sail is think roll-tack ie heeling the boat to turn a high metacentric hieght will not heel therefore turn slower))

The lower silouette enabled a better armoured raft like the German ships which proved hard to sink the downside was the vunerable Bow and stern sections outside the bulkhead inevitably flooded when penetrated due to low freeboard reducing turning performance further.

 

[delcyros]

In the late 1900´s, there were plans to fit anti-rolling tanks to german capitalships. These were intended to make them more stable as a gunplatform while keeping the high metacentric figure (or lowering it not by that much). Tests carried out with VON DER TANN & DEFFLINGER showed little practicability. These tanks were quite heavy and bulky, they did reduce the roll motion but gyro-gunlaying gears made them a matter of comfortability by then.
The USN also tried a number of experiments in this direction, including fitting of huge spin stabilized, 70 ts heavy gyros rotating with 2500rpm in the ship´s citadell. Again, the use was not in congruence with the gain after the general advent of gyro-gunlaying gears.

 

[martin worsey]

I've attached what is I think the most recent and definitive ]

Thank you for going to the trouble of providing the attached documents.
Whilst reading my post, I would apologise for the lack of clarity in the wording.
However, in reading Jurens’ article, it is clear that there is little evidence to suggest that Hood was destroyed due to a shell finding its way into the main magazine and detonating therein. There is also no criticism of the level of protection of the Hood barring that she was a WW1 warship and rather poorly protected by WW2 standards. Jurens does explain the reason that Bismark has more extensive protection as improvements in technology post WW1, particularly with respect to the machinery.
As you say, the most likely cause of her demise is that a shell penetrated a lightly armoured part of the ship, exploded in the 4” magazine and subsequently detonated the main magazine (i.e. a fluke). You will notice that the evidence for this is circumstantial and represents the most likely possibility insofar as this is mathematically feasible and fits with eyewitness accounts (there is no smoking gun as per Jurens’ investigation of the Invincible were the likely hit has been identified as it is visible with the submersible). Whilst I read about this a long time ago, my understanding is that the studies mentioned in Jurens’ articles could not produce a likely model for a shell finding its way directly into the 15” magazine without first going through a lot of armour and/or water and this was the reason for the indirect proposal.
Reading Campbell would indicate rather few (or no) examples of shells penetrating the main thickness of heavy armour and destroying something important. There are rather a lot of examples of shells going through weakly protected areas and causing catastrophic or potentially catastrophic problems. Thus comparison of Invincible (20% armour and 6” main belt) with Hood (30% armour and 12” main belt) shows the increase in maximum thickness of armour. Contrast this to Bismark (40% armour and 12” main belt). The risks identified post WW1 were not inadequate thickness of armour but that it was distributed insufficiently.
Consequently, I can see nothing which suggests that Hood should be viewed as a bad design (in the context of a WW1 warship). Perversely, Jutland allows a small risk that a WW1 warship (British or German) can blow up due to a freak hit; I am surprised that an example of this happening should be viewed otherwise. Criticism should more fairly levelled at the failure to modernise her between the wars and the tactical decision to match a 20 year old ship against a modern state of the art one.

 

[Coypus]

In the context of WWI she was not a bad design and would have been immune from any threat outside the Baden and could use her speed and gun range to destroy the opposition with impunity. The problem arose when navies with 14 inch warships as fast and 16 inch battleships appeared with modern armour. The Hood never should have been leading the line against the Bismarck, the fighting instructions and admiralty armour charts leave little doubt of the outcome. I dont think a deck penetration should be ruled out.

 

[Bullethead]

Consequently, I can see nothing which suggests that Hood should be viewed as a bad design (in the context of a WW1 warship). Perversely, Jutland allows a small risk that a WW1 warship (British or German) can blow up due to a freak hit; I am surprised that an example of this happening should be viewed otherwise. Criticism should more fairly levelled at the failure to modernise her between the wars and the tactical decision to match a 20 year old ship against a modern state of the art one.

The problem with Hood's design is that the armor distribution was based on RJW-vintage theories, as in shells arriving with a relatively flat trajectory from relatively short range. In this scenario, the idea of a thin upper belt and a turtledeck makes sense. But when the shells are coming from longer range at steeper angles, such a design is rather vulnerable because the trajectoryl is still flat enough to go through the thin upper belt and hit the angled part of the deck more or less square on, allowing relatively easy penetration of that.

This problem was actually recognized in WW1 because something rather similar happened to one of the QEs at Jutland. I forget which one but Campbell has a nice diagram of it so it would be easy to find if I had the time right now. Anyway, this is why the angled deck thing disappeared for the most part in postwar designs, and when old ships were modernized and you read of deck armor added, what they're usually talking about was adding a flat part over the angled part, just along the sides, not on top of the existing flat part of the whole deck. As Jurens notes, this was proposed for Hood but never carried out.

The point here is that Hood's armor scheme was already obsolete by 1916, but she was built that way anyway. Sure, they modified her on the slipway but didn't correct this particular problem, probably because they hadn't fully analyzed the Jutland data yet. If that's the case, then it's harder to call Hood a bad design. But if she was completed this way in knowledge of its problems, then that's IMHO a bad design. The failure to modernize her was also a rather bad decision.

But regardless of this, I don't see her loss as due to a freak hit. The path through the upper belt and angled deck was well-recognized no later than the 1920s and the RN took it seriously enough to propose the flat deck extension. The point here is that such a shell could have arrived anywhere along her length--it was just as easy to get into the 15" magazine as the 4" magazine because both had the same armor. IOW, just because the fatal shell most likely hit the 4" magazine instead of the 15", based on eye witness reports of the results, doesn't mean this was because the 4" magazine had less protection.

Now, that's with the path through the upper belt and angled deck. But there's an alternative path that just goes through the decks, which I tend to favor because it invokes Hood heeling over in her turn to port at the time of the hit. When Jurens first wrote his article, Hood's wreck hadn't been examined much if at all, so it was still unknown if she had started to turn yet or not. Now we know she was turning and had a reputation for heeling a lot in turns at high speed. This IMHO makes the upper belt / angled deck theory slightly less likely and the flat deck theory slightly more likely. And it just so happened that the shell probably hit over the after engine room, where the deck was sliightly thinner than elsewhere, which would have helped a bit more. However, it's not out of the question that it could have gotten through that way without the heel.

Bottom line, however, is that a shell got in there somehow, which wasn't unexpected, and that was that.

 

[delcyros]

HMS HOOD had very good armour protection. I am somehow amazed how people refuse to recognise this. In total, only BISMARCK, the two KGV´s and the LITTORIO´s had better armour protection when she sailed against B (I ignore RICHELIEU because she wasn´t in a state to do something by 1941). This doesn´t make her armour protection poor.
It had a belt made of good quality armour, inclined to offer more protection at medium to long range. Her CT, turret & barbette armour was excellent. The upper side belt has been recognised as a weakness because of the combination with a steep slope. The slope in itselfe is not a problem as long as it is shallow (QE-class) and not steep (R-class). Fortunately, or unfortunately -depending on the author You rely on- the UK design staff wanted to increase the protected volume of the ship by raising the main armour deck level. This required either a flat deck to join the upper edge of the main belt or the slope to be steepened from 70 deg to the horizontal originally towards 45 deg. in the R- class.
Ballistically, a flat slope of any meaningful thickness (say 3in up) is very difficult to penetrate for a projectile to have passed the main belt already. But it is possible and quite easy to penetrate a steep slope, particularely, if the trajectory allows the projectile to pass the thinner upper side belt instead of the main belt beforehand.
When the design of HOOD (or for that matter the R-class) was finalized, the UK had the expectation to have a shell to overcome armour and detonate in a short distance behind armour with a very violent explosion (high % lyddite burster charges) to damage armour (a criterium for a successful shell by then!) send the fragments along the flight axes of the shell into the ships vitals.
The 2" steep slope was designed in combination with a very well thought out internal armour layout to stop blast and fragments and localise damage. There is nothing wrong with this approach but when finally APC shells appeared with the ability to penetrate a rather long range behind the belt (GREENBOY APC 1918 in the UK), the steep slope couldn´t offer the degree of stopping power required to defeat this thread.

However, does it make the HOOD scheme clearly inferior to, say that of the NELSON-class? I don´t think so. HOOD (and the R and the R-BC´s, the KONGO´s, NAGATO´s and other ships) shared this weakness of the steep slope along their length of the citadell but NELSON had a weakness below it´s rather short main belt. A projectile could completely bypass the main belt without making to extensive underwater travel for the whole length at waterline impacts with the same results with nothing to stop blast or fragmentation effects behind.
To be fair, the innermost subdivision and protection was as poor in both designs. The machinery spaces were only seperated from the magazines by an 1" HT bulkhead. Even at more than 25 ft. miss distance, a considerable number of fragments from an 15" AP will be able to riddle this bulkhead with their hot fragments and enter the powder magazines. Now the target size goes up a bit: hits in either the main magazines, the sec. magazines or the after machinery spaces have a good chance to set up a magazine.

 

[Bullethead]

HMS HOOD had very good armour protection. I am somehow amazed how people refuse to recognise this. In total, only BISMARCK, the two KGV´s and the LITTORIO´s had better armour protection when she sailed against B (I ignore RICHELIEU because she wasn´t in a state to do something by 1941). This doesn´t make her armour protection poor.

Armor thickness is only 1/2 the story at most; its arrangement is at least as important if not moreso, especially as expected battle ranges increased. Prior to WW1, the USN had recognized that predreadnought armor arrangements were inadequate even at the relatively short expected ranges of the immediate pre-WW1 era. The RN had unequivocable combat data to support this by 31 May 1916, the very day Hood was laid down the 1st time, although (in that pre-computer world) it probably took until the end of the year to analyze it all. By that time, Hood had been restarted but she was low-priority so wasn't launched for almost 2 more years and took a further 1.5 years to complete. Despite this, her design was not altered a 2nd time, and it wasn't long after her completion that calls to eliminate her most obvious weaknesses were heard and ignored.

As such, it's hard to call Hood a good design. Her original design was flawed enough to be scrapped on the stocks and restarted. Her 2nd design was based on incomplete analysis of very recent combat data, but there was little doubt as to her inadequacies prior to her completion, and only shortly thereafter plans were proposed to fix her problems. IMHO, there was ample time to have fixed the problem Jurens concentrates on prior to her completion. But by that point in time, there were the impending Washington Treaty, the massive post-WW1 cuts in defense spending, and the looming global economic disaster in the aftermath of WW1. So I figure political/bureaucratic took precedence over operational concerns. That would certainly not have been a first in human, or even naval, history, hasn't been the last, and such things will doubtless continue until the sun goes out.

 

[delcyros]

I fully agree that HOOD was falwed but which design was not? I can´t think of many.
HOOD was vastly superior in layout and thickness of armour protection than either REVENGE-class or QUEEN ELIZABETH class battleships after their refits, than any of the japanese batlleshaips, safe YAMATO, than any of the french battleships, safe RICHELIEU, than any of the italian battleships, safe LITTORIO and finaly than any of the US battleships safe SOUTH DAKOTA& IOWA.
The most important lesson learned immediately after Jutland was that turret (13" max) and barbette (9" max) protection had to be improved drastically, HOOD´s exposed vitals consequently received even better armour protection than those of the KGV-class.
Agreed, HOOD was imperfect but second only to the most recent battleship designs. This doesn´t suddenly turn that ship into a poor design from a comparative point of view and it will hardly surprise us with the knowledge that two decades passed in between them.
You mentioned US battleship design prior to ww1. In my mind, US battleship design is kind of a mystery to me in this period. They kept on repeating a very old fashioned armour layout (with flat deck at about waterline level, the main belt usually submerged and the upper side belt unfavourably declined) from the early Pre-Dreadnought era (say, pre-MAJESTIC period) unti the NEVADA´s when they suddenly developed a very modern all-or-nothing layout, ideal to deal with delay action projectiles which weren´t aviable to the US until two more decades after the design was finalized and fired from a distance these battleships couldn´t even hope to reach with 15 deg elevation until another decade to come. Still some very old fashioned problems remained: The armour plates were installed in horizontal rows instead of vertical ones used anywhere else and created a general zone of weakness at their joints (waterline level) and the slope behind was unnecessary steep (there already was a high mounted flat deck) and to thin to offer more than splinterprotection.

 

[Von der Tann]

Hood was among the best ships of her time, and she was probably the best ship around then, but when she sailed against Bismarck, this time had passed. This is pretty much the whole story, she had not been built to withstand 1940ies weaponry.

 

[Coypus]

Couple of things from Bill Jurens when asked to compare Hood to Arizona

On different Cordite

"In the final analysis, except in very closely controlled conditions -- and perhaps not even then -- a magazine explosion essentially represents a highly chaotic and relatively rare event which by its own nature tends to obscure the exact mechanisms involved. In that regard one might expect fairly significant variations in detail failure modes even if one could by some miraculous process conduct a series of systematic tests aboard structurally identical vessels. The degree and type of damage involves the weight of propellant burned, its rate of burning, and a collection of ill-understood variables which determine the direction and rate of flame propagation from charge to charge. The question asked was whether the damage to Arizona would have been greater had British rather than American propellant been involved. The short answer is that it is probably impossible to tell. British (and to a lesser extent, American) propellant compositions varied over the years, and some effects are undoubtedly due to propellant aging. Further, because Cordite produces more energy per pound than Nitrocellulose type propellants, the same amount of energy could be packed into a smaller space on British vessels, so one may (or may not) feel it appropriate to correct for variants in tonnage of propellant actually carried aboard, which for a given amount of shooting would be smaller on a British vessel than an American one. To this, one must add the almost entirely unknown effects that might accrue from differing storage procedures, which though broadly similar in both navies, often varied significantly in detail."

Overall, one might expect a less-violent explosion in an American vessel, with lower overpressures extending for somewhat longer intervals, i.e. with similar impulses but variant pressure-time curves. It would seem likely that, again in a very broad sense, that somewhat less venting area might be required to prevent a catastrophic magazine explosion in an American rather than a British vessel. The trade-off, essentially, appears to have been weight; is it overall better to carry a greater amount of less energetic propellant (the American approach) or a somewhat lesser amount of more energetic propellant (the approach used by the British and most other navies)?

A good question, upon which honest and intelligent men would (and probably did) disagree... "

On Whether the Arizona would have broke up at sea

"I have looked at the Arizona explosion in detail, by examining the large scale drawings of the wreckage prepared by wreck divers in 1942-1943, the ship's general arrangement plans, and the film of the explosion and/or the rather extensive still photo collection which the Navy made during the course of salvaging what became in the end a constructive total loss. While it is correct that the forward part of Arizona's hull remains connected to the after portion, this is probably because the ship sank in very shallow water and because it was stationary at the time the explosion occurred. Had Arizona experienced a similar explosion in deep water at sea and underway, it is almost certain that the forward portion of the hull would have detached itself and presented itself as a separate fairly substantial chunk of wreckage. It is difficult to say for certain -- a lot would depend upon exactly how things 'came apart' forward -- but it is possible (though improbable) that the stern section of Arizona may have remained afloat for some time after the intial blast. It is more likely that fairly rapid flooding of the engineering spaces aft of the bridge would have removed sufficient buoyancy and stability to result in a capsize and plunge by the bow. If the stern sank quickly, it is probable that there would have been a failure of the stern section aft of the aftermost turret as the ship plunged. If the ship sank slowly, through progressive flooding, as for example in the case of HMS Audacious, then there is a good probability that the stern section would have remained attached to the ship all the way to the bottom, though heavily strained and distorted."

On Forward Hood Mag explosion

"I am grateful that some have taken the time here to once again point out the correct mechanism, i.e. hydrodynamic implosion, which resulted the forward hull failure on Hood. There was no, repeat no, forward magazine explosion on Hood, and in that regard the television programme done in 2001 is both incorrect and misleading in suggesting that a forward magazine explosion took place. It is incorrect insofar as a forward magazine explosion never did take place -- in fact there is not even a magazine located in the area where the observed failure took place -- and misleading in implying that the forward magazine explosion idea represented some sort of concensus of the investigative team. It did not. As a member of the Society of Naval Architects and Marine Engineers panel SD-7 (Marine Forensics), I was the ONLY member of the expedition specifically tasked with the forensic analysis of the wreck regarding the dynamics of the magazine explosion and the structural failures which followed, and I very strongly dissented with the presentation of the forward magazine explosion 'theory' -- if one might call it that -- as fact. To this day, I know of no certified naval architect, marine engineer, or ordnance expert which supports the idea of a forward magazine explosion on Hood, or who feels that a forward implosive failure and separation as in any way improbable. In forensic engineering we rely more on physics than imagination."



On Bismarck (and others stern sections)

"My observation of Bismarck is that the designers were very heavily concerned with weight savings in unarmored and/or lightly armored sections of the ship, this probably in order to release more weight to put into the belt, the decks, and the machinery plant. The result was that the required weight-increasing 'tapers' were not installed in every place they might have been desirable, with the result that lighter sections probably broke off at lower-than-normal stress levels. This lack of stress fairing, coupled with the imposition of a welded rather than rivetted joint probably led to the type of failures we so often see on German (and other) ships. The failures were, in brief, most probably attributable to an ill-advised attempt to weld when the technology of the time (and the experience of the designers) was not really up to it, coupled with an almost complete lack of stress fairing at the transition point between the 'hard' midship portion of the hull and the must 'softer' ends. "

Hope you guys find them as imformative as I did

 

[Coypus]

From the same thread there is an interesting piece on the remains of the Defence (Jutland)



"I was fortunate to have been able to investigate the wreck of Defense in about 2004, whilst doing a documentary on the Battle of Jutland. It is clear that the forward magazine(s) exploded violently, destroying the forward part of the ship, but (as is so often the case) there was little physical evidence to suggest that there was any significant propagation towards the stern. Doors in the turrets were open, suggesting that there was some time to escape after the forward magazine explosion took place, and although some turret roofs were missing, it appears that most or all of these losses were due to the gun breeches pushing the roofs via over-depression of the guns. There were, in cases we could investigate, unburned cordite charges -- and plenty of them -- in the hoists, etc. My investigation of the plans of Defense and the arrangement of the magazine corridors would suggest, at least to me, that propagation via that route would have been unlikely."


"Mr. Sanderson is correct in noting that eyewitness accounts do indeed suggest some sort of progressive explosion or explosion amidships on Defense. The eyewitnesses are clearly mistaken. As we say in marine forensics, the steel doesn't lie. The midship sections of Defense remain more or less intact, with all turrets in place though some are askew on their roller paths etc. but this appears to be primarily due to the wreckage collapsing as the structure below deteriorates. I have learned over the years that eyewitness accounts of sudden unexpected phenomena are rarely reliable, especially in the singular. If one has quite a few independent eye witnesses, one may by collating common observations come up with a reasonably accurate overall rendition of the event, but in most cases -- with notable exceptions -- the observations of a single eyewitness are rarely of much utility, and the observations of even groups of eyewitnesses are rarely dependable regarding details. "

 

[rgreat]

So? Defense still exploded and sunk shortly afterward.

What is your point?

 

[Coypus]

So? Defense still exploded and sunk shortly afterward.

What is your point?

Did not know I was making one, though I must admit it is always good to increase your knowledge and understanding of a subject that interests one, always interesting to find out things happened differently than the accepted story even if the end result for the Defence was little different. The Defence appears to have an armoured tube to protect the amunition hoist and simmilair barbette armour thickness to the "I"'s forward. Wondering what influence that would have in venting or concentrating the blast

 

[Bullethead]

Did not know I was making one, though I must admit it is always good to increase your knowledge and understanding of a subject that interests one,

What you're now posting as new revelations to you are exactly what everybody here has been trying to explain to you all this time. I think they prove our points and not yours.

 

[Coypus]

So all this time people have been trying to explain to me that every other navies ships blew up in world war II no matter what cordite was used.

 

[Bullethead]

So all this time people have been trying to explain to me that every other navies ships blew up in world war II no matter what cordite was used.

NO. As you've been told dozens of times, German ships didn't blow up from propellant explosions in WW2 or WW1. There is exactly zero evidence for it, and mucho evidence to the contrary, which many folks have shown you repeatedly since you started making this ridiculous claim.

What I was trying to say is that the things you posted above like they were new revelations to you are things the rest of us have known and cited for years. So you can drop the attempt to take snippets from sources out of context in weak attempts to make them say things they don't in toto.

 

[Coypus]

If you want you can go over and read the whole thread to see if I have taken anything out of context. Google Jurens and Arizona the thread is at Nav Weapons. Its a very good thread actually sometimes boards can get bogged down on Bismarck v Yamato type threads and the like.

 

[saddletank]

In Coypus' defence I didn't read these quotations as trying to prove any point either way; they were just information. Defence blew up at Jutland, we all know that and the fact that three battlecruisers also did makes it highly likely that all four ships were destroyed via the same failure - and not from different mechanisms.

The information about Arizona was new to me and though fascinating the statement that had she blown up underway and in deep water might or might not have resulted in her breaking completely in two was not especially relevant to the current discussion I don't think.

 

[Coypus]

In Coypus' defence I didn't read these quotations as trying to prove any point either way; they were just information. Defence blew up at Jutland, we all know that and the fact that three battlecruisers also did makes it highly likely that all four ships were destroyed via the same failure - and not from different mechanisms.

The information about Arizona was new to me and though fascinating the statement that had she blown up underway and in deep water might or might not have resulted in her breaking completely in two was not especially relevant to the current discussion I don't think.

Thank you, I appreciate that.

 

[martin worsey]

From the same thread there is an interesting piece on the remains of the Defence (Jutland)



"I was fortunate to have been able to investigate the wreck of Defense in about 2004, whilst doing a documentary on the Battle of Jutland. . "

With respect to the documentary mentioned in the above quotation, this would appear to be “Clash of the Dreadnoughts”. Whilst there have been previous incidents of documentaries distorting Mr. Jurren’s findings, as he appears to have collaborated in the making of this one, it could be assumed that it is reasonably reflective of his opinions. The suggestion with respect to the loss of the British ships to explosions is as follows: -

• In 1913, Sir George Callaghan instigated an increase of 50% in the quantities of ammunition carried in the large British warships. This was due to an expectation that low accuracy of gunnery at battle ranges could cause the fleet to run short of ammunition before a decisive outcome had been reached.
• Adequate storage was available for shells within the shell rooms; however, this was not so for the propellant which thus had to be stored outside the magazines.
• Large quantities of cordite was scattered around on the seabed as well as evidence the evidence of it being found in the hoist of Defence. It was suggested that this was evidence of the ships being overloaded with cordite.
• It was also suggested that, in order to increase the rate of fire, cordite was stockpiled in breach of handling regulations and anti flash doors were removed or left open to improve the rate of fire.
• It was considered desirable to investigate the flash protection doors to establish if these had been buckled or destroyed by explosion and thus overwhelmed. Unfortunately it was not possible to find any evidence either way and the expedition was not permitted to enter the wrecks.
• Overall, the conclusion of the documentary was that the ships blew up due to poor handling of cordite insofar as a powder trail was left from turret to magazine.