A naval might have been "Tirpitz -v - Iowa"

[Tiornu]

So are the Iowa's side defenses.

That's another misconception apparently caused by confusion between two separate caisson tests and the results thereof. Assessment of the tests noted where the system would failed and why, but that's not the same as structural flaws. North Carolina also had thick armor in her TDS, and no one claims this was a flaw. In fact, the USN considered Iowa's TDS layout "approximately equal" to NC's despite the reduction in depth. In addition, Iowa had a liquid loading system that was considered superior to NC's.

Scharnhorst's TDS is also deeper than Iowa's over much of the center portion of the ship.

I'd be interested in how you determined that. Note also that the lowest portion of the Scharnhorst blister system provides no subdivision at all between the hull plating and the torpedo bulkhead.

Scharnhorst's TDS also covers a greater fraction of the ship's length, and leaves shorter ends unprotected and open to large trim moment flooding.

That appears to be true, but I'm not sure what difference it makes. Scharnhorst's system will likely fail in those sections anyway. Maybe against small warheads it would offer a significant advantage.

Scharnhorst is credited with absorbing 12 full sized 21" torpedos during the North Cape action.

Eight is a more realistic figure. German sources gild the lilly by claiming numbers of hits that imply absurdly high hit rates. And it bears pointing out that Scharnhorst did not survive the incident. To gauge the ship's resistance, it's more instructive to look at hits she survived.

At the very least, one would have to credit Scharhorst's TDS with punching considerably above the ship's weight when compared to those of Iowa, even if it is not entirely certain whether Scharnhorst's actually exceeded Iowa in absolute total resistance.

I'm not sure what you're saying. But I will agree that Scharnhorst's extensive subdivision and high GM are among her best attributes, at least as regards survivability.

[chuck]

A centerline bulkhead and armored deck at the lower edge of the belt put Tirpitz at a decided disadvantage from a damage resistance standpoint.

Go look at CombinedFleet's "baddest" page: http://www.combinedfleet.com/baddest.htm

That page is comically flippant in its pro-American biase. If it had only incorporated "Fear factor" into the weighing it would acquire the same entertainment value as the Military Channel's list of top 10 battleships in history.

A centerline bulkhead constitutes no major disadvantage in side torpedo defense unless the ship has very poor stability and torpedo defence to start with. It does, however, offer the considerable advantage in limiting the effect of under keel damage, isolating damage to the power plant, and greatly improving the ship's structural efficiency. I think the argument against centerline bulkhead in a stable and well designed ship is largely without merit and kept going mainly by the pride of those whose favorite battleships didn't have them.

The low turtle back armor deck reduce the volume of the citadel and exposes more hull volume to enemy fire, but in return it makes the citadel underneath far less vulnerable to gun fire at ranges where decisive results are more likely to be achieved. It trades away protection for a ship's equipment in return for stronger protection to the ship's absolute vitals.

[chuck]

The American Navys damage control abilities were legendary.

Legends are useless for reliable comparison.

[Werner]

A warship with a centerline bulkhead will develop a list sufficient to incapacitate her turrets long before she becomes buoyantly unstable.

Look over the statistics regarding (1) the number of Japanese battleships and cruisers lost to a single torpedo (all had centerline bulkheads), and (2) the number of them which capsized before they were awash at weather deck level.

Evidently the RN agreed with the USN; the Majestic and Colossus had centerline bulkheads deleted from the design after the experience with Ark Royal.

Helena, Boise and CL Houston were outstanding examples of how lack of centerline bulkheads presented a safer platform for the crew to work or evacuate in the case of extreme underwater damage.

The Japanese and USN provide many examples of this kind of damage, and it makes for interesting study.

The photo below looks down into Houston's hangar. Damage like this would have caused a substantial list and additional strain on the already weakened girder if there had been a centerline bulkhead.

[chuck]

In a relatively static situation, a breached ship with a centerline bulkhead can counter flood the space on the opposite side if necessary. A breached ship without a centerline bulkhead will effectively automatically counter flood the space on the other side whether or not that is necessary. Similarly in a static situation a breached ship that finds that counter flooding is no longer necessary can pump out that counter flooded space. A breached ship without a centerline bulkhead can not do so because the counter flooded space is also breached. So in a relatively static situation, there is no damage control merit in not having a centerline bulkhead.

In a dynamic situation where a ship receives damage and begins to flood into its interior spaces, the situation brakes down into 2 catagories.

1. The flooding into the interior space is relatively slow, meaning there is time, while flooding, to take effective countermeasures such as counter flooding, then the situation is really quasi-static, and the above analysis apply, and there is no merit to not having a centerline bulkhead.

2. The flooding into the interior space is fast, meaning there is no time to take effective countermeasures such as counter flooding in the amount of time it might take to fill up the ruptured interior space. In this case if the interior is large enough, a dividing centerline bulkhead might cause the ship to capsize before countermeasure takes effect, and thus centerline bulkhead becomes a potentially serious damage control hindrance.

Two factors determines which category torpedo induced flooding falls into:

a. Is there reasonable torpedo defense. Reasonable torpedo defense, if successful, completely contains the rupture caused by the torpedo and keeps the interior spaces of the ship water tight. Furthermore it does this while limiting the amount of water admitted into itself so that no dangerously large list results. Even if defeated, reasonable torpedo defense still contains bulk of the rupture caused by the torpedo, and limits beaching of the ship's interior spaces to localized punctures rather than whole sale rupture, thus making flooding into the interior spaces slow and quasi-static. So whether defeated or not, reasonable torpedo defense discourage the development of catagory 2 situation when a ship is struck with torpedoes.

b. Is there good stability and interior partition. A ship with good interior partition floods little when breached. A ship with good stability lists less for the same amount of off center flooding. So good stability and interior partition both discourage the development of category 2 situation.

WWII era cruisers and light carriers have no torpedo defense systems to speak of. Their interior compartments are large in relation to their size, and their stability is therefore low in relation to the amount of flooding that can be expected from a single side rupture. So cruisers and light carriers tends to flood in the category 2 manner and are not suitable for centerline bulkheads.

WWII era battleships are a different story. They almost all have reasonable torpedo defenses. Their interior compartments, particular those whose engineering spaces are subdivided by centerline bulkheads are small in relation to their size, and their stability, especially those of the broad beamed German and Japanese designs with centerline bulkheads, are high. So battleships are suited to having centerline bulkheads, and the newer German and Japanese battleships are particularly well suited to having centerline bulkheads.

Now regarding specific issues you raised:

A warship with a centerline bulkhead will develop a list sufficient to incapacitate her turrets long before she becomes buoyantly unstable.

A center divided battleship, if necessary, can counter flood interior spaces on the opposite side to remove the list. At the end of the counterflooding, her flooding would be equal to that of the battleship without center bulkhead. An undivided battleship, however, can not stop herself from counterflooding even if there is no need. More over, if the center divided and counterflooded battleship later receives additional underwater damage on the opposite side, she can pump out the counter flooded compartment to restore even keel and regain buoyancy. A battleships without centerline bulkhead can not do so.

Look over the statistics ... battleships and cruisers lost to a single torpedo (all had centerline bulkheads) ... Evidently the RN agreed with the USN; the Majestic and Colossus had centerline bulkheads deleted from the design after the experience with Ark Royal.

As mentioned before, cruisers and lighter carrier examples don't count in assessing the merit of a center-line bulkhead in a battleship. But if they were to count, I can also mention a cruiser with centerline bulkheads that took 2 torpedoes on the same side and steamed home, a feat very few undivided cruisers managed to match.

No modern or even reconstructed battleships of WWII era were lost at sea to one torpedo. The battlecruiser Kongo, which was lost to a single torpedo, was a WWI era ship without modern torpedo defense, and might as well be considered a cruiser for the purpose of underwater defense.

Japanese damage control procedure is known to be both flawed and flaunted, and available damage control facilities are known to frequently be left unused for no clear reason. This limits the usefulness of using results of Japanese damage control practice to evaluate the potential effectiveness of basic damage control designs. Even so, Japanese experience still does not afford a clear example of a case where a capital ship would have survived but for the centerline bulkhead.

...number of them which capsized before they were awash at weather deck level.

Which battleship without centerline bulkhead managed to stay upright without capsizing until her weather deck was awash?

[Werner]

If you were paying attention, I lumped cruisers and battleships together for the purpose of discussing centerline bulkheads. Since so few battleships were actually involved in WW.II, cruisers are a more useful point of discussion.

Barham, a battleship with a centerline bulkhead took three hits placed so close as to be essentially one hit.

If I recall correctly, the list of Prince of Wales rendered useless her 5.25 inch battery, because they could not be manhandled in train against the angle. Counterflooding is a devilish thing and it certainly did not assist her.

It is at least arguable that a ship designed without centerline bulkheads can be arranged to have more comprehensive transverse compartmentation, a more useful way to preserve buoyancy and stability in a damaged state.

We're not going to settle this between ourselves. What we need is a comment from one or more of the naval architects who belong to our little society.

[chuck]

If you were paying attention, I lumped cruisers and battleships together for the purpose of discussing centerline bulkheads. Since so few battleships were actually involved in WW.II, cruisers are a more useful point of discussion.

Cruisers are not suitable for lumping together with battleships because cruisers do not have TDS, and so when they receive torpedo hits, the speed of flooding would likely overwhelm manual counter flooding. With an effective TDS, a battleship can slow flooding so that she could neutralize the off axis flooding effect of a centerline bulkhead if necessary, while take advantage of the improved compartmentization offered by the centerline bulkhead.

Barham, a battleship with a centerline bulkhead took three hits placed so close as to be essentially one hit.

Even if we grant that Barham took what is effectively one giant torpedo, we still have the fact that Barham is essentially a unmodernized WWI era battleship, she also didn't have any effective TDS, and she was overwhelmed by speed of flooding in a manner similar to a cruiser and not to any battleship with an effective TDS.

If I recall correctly, the list of Prince of Wales rendered useless her 5.25 inch battery, because they could not be manhandled in train against the angle. Counterflooding is a devilish thing and it certainly did not assist her.

POW had no centerline bulkhead, and yet she still listed unacceptably. But the point here is a battleship with centerline bulkhead would do no worse in the same situation. If necessary that ship could simply flood the opposite compartment and achieve the exact same flooding pattern as actually occurred in the POW. But unlike the POW, she could pump out half of her flooded space afterwards.

It is at least arguable that a ship designed without centerline bulkheads can be arranged to have more comprehensive transverse compartmentation, a more useful way to preserve buoyancy and stability in a damaged state.

You probably mean longitudinal compartmentization, as in the current context a ships said to be without centerline bulkhead is taken to mean it has no major transverse partition of the large engineering spaces. If that is what you meant, then it is not true. Let's look at both of the major WWII era battleships with centerline partitions:

Bismark: She had 3 shafts, and her engineering space is divided lengthwise into 4 major compartments by 4 complete transverse bulkheads. So the longitudinal compartmentalization of the 3 shafted Bismark's machinery space is actually slightly better than those of any 4 shafted battleships with anglo-American style unitized machinery and no centerline bulkhead. This is all the more significant because, had a 3 shafted battleship adopted Anglo-American style unitized machinery with no centerline bulkhead, that battleship would only have 3 major longitudinal compartments and 2 major transverse bulkheads in her engineering space, a much worse level of longitudinal compartmentalization than what was achieved in the Bismark.

Yamato: She had 4 shafts, and her engineering space is divided lengthwise into 4 major longitudinal compartments by 3 complete transverse bulkheads and 1 interrupted transverse bulkhead. This is the same level longitudinal compartmentalization as in any other 4 shafted battleships with Anglo-American style unitized machinery with no centerline bulkhead.

This shows that battleships with centerline partitions do not need to, and indeed do not in practice, suffer from reduced level of subdivision from front to back. They so, however, enjoy much superior subdivision from side to side.

There is an additional benefit to subdividing the large engineering space with longitudinal bulkhead that would become particularly important if the ship was to receive the torpedo damage in moderate to heavy seas. In an ship without centerline or longitudinal partition of major engineering space, any partial flooding of the engineering space would result in a free surface as wide as the ship. Free surface allows the water to slosh from side to side with the roll of the ship, effectively changing the weight distribution of the ship in a manner that amplify the rolling motion , thus encouraging the partially flooded ship to wallow deeply in any sea. This free surface effect is well known to naval architects. In a center-divided ship, the free surface is cut to at least one half, in the case of Bismark 1/3, and in the case of Yamato 1/4, the width of the ship. This means there is greatly reduced surface effect. This means flooding in these ships would have much less effect on the ship's normal rate and amplitude of roll. Thus these ships would also be considerably superior to a ship without centerline division in the case of underwater damage in heavy weather.

This reduction of free surface effect would also similar help a ship with center division in the case of additional serious underwater damage after inboard flooding. In an undivided ship, if the ship developed another heavy list after receiving initial flooding, the water in the undivided space would slosh towards the direction of the list and help increase the list. In a ship with transverse division, this effect would also be significantly reduced.

[Foeth]

This reduction of free surface effect would also similar help a ship with center division in the case of additional serious underwater damage after inboard flooding. In an undivided ship, if the ship developed another heavy list after receiving initial flooding, the water in the undivided space would slosh towards the direction of the list and help increase the list. In a ship with transverse division, this effect would also be significantly reduced.

In a ship with a transverse bulkhead, the effect of one half of a section flooded is worse than the entire section flooding. If counterflooding is achieved, it's better off but only given enough time. You can loose the ship in cases of extreme damage before counterflooding is completed. Note that counterflooding can be used with completely filled tanks, further dimishing stability issues. That is, if you're still afloat.

Free surface allows the water to slosh from side to side with the roll of the ship, effectively changing the weight distribution of the ship in a manner that amplify the rolling motion , thus encouraging the partially flooded ship to wallow deeply in any sea.

Not necessarily, it can also damp the rolling. Depends on the size of the flooded section, degree of filling, and the rolling period of the ship. Some tanks are purposely applied to ships to damp rolling. But, I guess most of the time it works against you.

[Walt]

The point of the original post was what would the outcome be between these two in a show down..
Torpedos would not be a factor.. A plunging 2700 lb. AP round from a 16" gun would cause considerable damage to the Tirpitz.. Maybe blowing a hole thru the ships keel much less doing serious damage to her free board area.. ( depending on fuse settings).. This factor alone puts the Iowa at greater advantage.. The Iowas faster speed and longer effective Gun ranges and projectile weights would also be a big factor in a duel.. Of course in the fog of battle many factors could tip the scales from skipper and crew capibilities, weather factors and "luck".. These were not part of the question.. from this question I can only assume that in "normal" conditions if these 2 great ships were to come upon each other in the open sea with matched skippers and crews who would be favored.. I don't see it as much of a match at all.. We could talk about what if's, engineering theroy, and design all day but we will never know what effect that would have had on getting hits from 2700# rounds or in the case of the Iowa getting hit by 1700# rounds.. But we do know that the facts are in reality the Iowa had huge advantages..all of them in her ability to strike 1st , hard and often from a safe range that due to her better speed she could maintain this range never falling under the Tirpitz's guns....no science or theroy there.
We do know that the Tirpitz is gone as is the Bismark..as are the Yamatos, Hood, POW and other great battleships friend and foe ,all were sunk in combat and almost 70 years later all the Iowas are still here and a few of them recently retired.

[Foeth]

The pyramids are also still here. And they are a far better design than the Iowa's who are now all in reserve. This also proves beyond a shadow of a doubt that gun range says nothing about a weapon's durability. Plus, hundreds of pyramids were built against only 4 Iowa's. Pyramids are clearly superior.

[Walt]

The pyramids are also still here. And they are a far better design than the Iowa's who are now all in reserve. This also proves beyond a shadow of a doubt that gun range says nothing about a weapon's durability. Plus, hundreds of pyramids were built against only 4 Iowa's. Pyramids are clearly superior.

True about pyramids Foeth .. On that fact we agree, But apples are sweet as are cherries but one is not the other!
I also beg to differ.. a Gun's range has loads to say about a "SHIP"S" duribility eh? 4 Iowa's built.. 4 Iowa's still afloat...

[bengtsson]

Tirpitz was designed for naval action in the North sea and North Atlantic. Shorter ranges were expected due to average weather conditions. How does that square with an Iowa, was she built for maximum range combat in the clear blue Pacific?? Appels and Oranges maybe?
I don't know, Battleship design isn't my field. Was there a built in difference on account of different battle conditions expected. Was Iowa a later design?

Bob B.

[Foeth]

4 Iowa's built.. 4 Iowa's still afloat...

I could call that wishful thinking, although I miss the thinking element. Apparently a good design is never being in an actual combat situation where you can get hit Well, I must remember to design all ships so that they never see combat. How much more durability can you have?

[Walt]

Tirpitz was designed for naval action in the North sea and North Atlantic. Shorter ranges were expected due to average weather conditions. How does that square with an Iowa, was she built for maximum range combat in the clear blue Pacific?? Appels and Oranges maybe?
I don't know, Battleship design isn't my field. Was there a built in difference on account of different battle conditions expected. Was Iowa a later design?

Bob B.

Iowas were built for sea superiority Atlantic or Pacific. To be the biggest and baddest that could be put afloat post treaty limitations. Designed when Battlewagons were still percieved to be the Queens of Battle..Oceans for use were not a design issue, infact their high bows were a very good design for North Atlantic conditions. As for not being in a situation as to get hit has as much to do with your enemy avoiding you as it does with design. Not to mention your enemys capability to engage you.
This comparison of Bismark to Iowa classes is not a good one. Maybe a better comparison would be with SoDaks/Washingtons but even they have the better power numbers.. I don't know about speed but I'd wager the SoDaks and Washingtons were as fast or faster than the Bismarks too.

[chuck]

Iowas were built for sea superiority Atlantic or Pacific. To be the biggest and baddest that could be put afloat post treaty limitations.

What does "were built for" mean in any comparative schemes? Were everyone else's battleships built for sea inferiority, and to be the tiniest and wussiest that could be put afloat? In the grand scheme of contemporary battleship projects, Iowas were not particular big, and certainly not at all that bad, whichever way you would like to interpret the word "bad". Iowa certainly was not a post treaty battleship. It was specifically designed to the terms of the escalation clause of the second London Naval agreement which allowed for 45,000 ton, 16" battleships. Her direct equivalent would have been the British Lion class. Cheaters who pretended their ships fell under the same restriction, but were in fact intent upon making their roughly equivalent ships much "bigger" and "badder" includes the French, Germans, Soviets, and Japanese.

You should stop watching "Victory at Sea". Iowas were primarily motivated by the fact that the USN had nothing with which to catch the Kongos in the pacific. In pre-war war gaming, the US determined that regardless of their pre-Jutland heritage, these Japanese battle cruisers could cause huge headaches to the US fleet in the pacific as it was then constituted.

[bengtsson]

With my limited understanding, I thought that Bismarcks were built with an armour scheme that favoured a shorter range battle. A study was done of weather conditions in the North Sea/North Atlantic and it was found maximum visibility conditions were a very rare event. So they were more than willing to be vulnerable at longer ranges and to be more proof aginst hits at medium ranges. I forget where I read that . My years at sea in the Pacific remind me that visibility was often maximum. Nothing like the North Sea. I'de think Iowas would be built for maximum protection and hitting power at the longest ranges possible.
By the time Iowa hit the water, an action with Bismarcks would be very unlikely. Just due to the state of the naval war by then.

Bob B.

[Werner]

Walt, long range gunnery aided by spotting aircraft and other observers, and later Radar, was USN doctrine after WW.I. This led to some interesting consequences during the Washington and London treaty negotiations. Because long range places different demands on a ship's protection scheme than normal combat, the arrangement and proportion of armor weights were quite a surprise to the British (and perhaps other) delegates. The leader of the US delegation wrote the State Department to suggest these details be treated as state secrets and not shared with other negotiators.

It is at least reasonable to assume that these revelations impacted British designs of the 1930s.

[chuck]

In the interwar period, British, American, Japanese and French navies all effectively built their battleships for engagements in the 20,000 - 30,000 yard range. They were designed to be highly survivable to hits at those ranges. Inside 20,000 yards these ships all becoming increasingly vulnerable, as the range of aspect angles present to their opponent inside which they would risking a serious citadel penetrating hit increases from 90 degrees. The Germans appeared to build their battleships for 10,000 - 25,000 yards. Their citadels continue to be immune, thanks to the low armor deck, down to 10,000 yards, and remain difficult to penetrate to something even closer. I think the Germans in fact got the balance right for they of battleship engagements fought before 1944.

Everyone harps on the trade-offs the Germans made, and points to things the Germans gave up that everyone else got as if Germans were simply stupid or obstinately backwards. I think the Germans in fact thought clearly, made reasonable assumptions, and made a decision that actually turn out to be a good one for a naval war in 1939-1943. Of course they Germans didn't intend to fight a naval war until 1948, but that's a different issue.

[bengtsson]

Everyone harps on the trade-offs the Germans made, and points to things the Germans gave up that everyone else got as if Germans were simply stupid or obstinately backwards. I think the Germans in fact thought clearly, made reasonable assumptions, and made a decision that actually turn out to be a good one for a naval war in 1939-1943. Of course they Germans didn't intend to fight a naval war until 1948, but that's a different issue.

I'de tend to agree with that statement. I don't think the Germans made design decisions without looking at the "Most Likely" battle conditions they would encounter, where they planned to fight. I've often said, but could be wrong, "The ideal is the enemy of the practicle".
The German Bismarcks were built to fight other BBs. To fight them first in the North Sea and secondly out in the North Atlantic. On any given day you were more likely to be fighting in lower visibility and thus shorter ranges. There armour would need to be proof at the shorter ranges , as they were the most likely battle ranges to be encountered. As Jacky Fisher often made clear, you want to build ships to fight the Battle you are most likely to encounter, you don't build a ship and then try and fit the battle to suit the ship.
I don't see anything wrong with the German solution for the battle areas they intended to fight in. Modern technology changed things, but really only after 1943.

Bob B.

[ar]

An increase in beam from 108' in the Iowas to 121' for the Montanas, allowed the machinery spaces to be divided into THREE, longitudually.
See Friedman, battleships pages, 340 and 342. Also Dreadful and Ghastly, pages 170 and 171.
Comments welcome.