All things considered...(Pearl Harbor)

[CaptHawkeye]

...what can be said about the performance of damage control practices and technology on board US warships at Pearl Harbor? Considering the methods of the attack, the timing, and of course, the sheer volume of firepower battleship row endured, just how did every ship's damage control hold up in the end? When you think about all of those battleships, tied next to eachother and basically taking one bat to the face after another, can't it be said they handled themselves quite well? You'd think more of them would have ended up like Arizona.

For the sake of the question, we're forgetting that many of them could be easily recovered since they were sunk in Pearl's shallow waters and convienently next to the harbor's plethora of undamaged repair yards.

I ask this because it's pretty hard to get an idea of the quality of US damage control systems in practice, because heavily armoured US battleships rarely faced tests of their defensive capabilities. Unlike the IJN's heavy warships, which frequently encountered DC performance well below projected capabilities. (lol Yamato, Kirishima, pretty much every one of their fleet carriers.) Their's a lot of matieral written on the "paper" projections of the USN's defensive qualities, but cases of US battleships suffereing serious damage from enemy attacks post-Pearl are rare to non-existent. A lot of the kamikaze attacks on US BB's ended up doing little more than scratching the paint, but I doubt the BBs were often the kamikaze's primary targets anyway.

[Sea Skimmer]

...what can be said about the performance of damage control practices and technology on board US warships at Pearl Harbor? Considering the methods of the attack, the timing, and of course, the sheer volume of firepower battleship row endured, just how did every ship's damage control hold up in the end? When you think about all of those battleships, tied next to eachother and basically taking one bat to the face after another, can't it be said they handled themselves quite well? You'd think more of them would have ended up like Arizona.

The US fleet was caught at anchor in a peacetime material condition with all ships having reducing manning to some degree or another due to shore leave. What’s more most ships either took rapid overwhelming damage, Arizona, Okalahoma, West Virginia, or suffered relatively little like Pennsylvania and Tennessee. California was completely screwed with several manholes in the double bottom opened, and every watertight door on the ship open as well, and then to round it off a premature order was issued to abandon ship. Few of the ships fall into a category in which damage was serious enough to risk sinking, and yet which didn’t sink before any reaction could be made.
In general damage control was good though, rapid counterflooding saved West Virginia from capsizing, cruisers Raleigh and Helena both remained afloat after torpedo hits in the first minutes before condition Zebra could be set. Many older ships however suffered from poor watertight integrity (not open doors, but the bulkheads just plain leaked) such as Nevada and damage control can do nothing against this. It took yard work after the attack to fix the problem. The reaction to the attack in general was better then anyone, especially the Japanese really expected for a surprise attack. On most ships ammunition was literally under lock and key, and yet most ships had guns firing even as the first torpedo planes attacked. On destroyers Cassin and Downes the ships 5 inch guns had actually been disassembled for maintenance in the yard, but workers found the parts and reassembled the guns as the attack went on and had them in action against the second wave.

I ask this because it's pretty hard to get an idea of the quality of US damage control systems in practice, because heavily armoured US battleships rarely faced tests of their defensive capabilities

That doesn’t make sense, battleships already have the highest resistance to enemy weapons of any type ship, so they should provide the least useful information on the relative effectiveness of damage control. In any case, American battleships did take quite a bit of damage latter in the war, including two separate collision incidents which inflicted massive damage, several torpedoing, being riddled with gunfire and a number of bomb hits.

Unlike the IJN's heavy warships, which frequently encountered DC performance well below projected capabilities. (lol Yamato, Kirishima, pretty much every one of their fleet carriers.)

Yamato and Kirishima most certainly are not major failures of damage control, both ships simply took overwhelming damage and neither exactly sank quickly. Japan had shitty damage control for sure, but in many respects it wasn’t any worse and in some cases was better then that of other fleets besides the USN. Shōkaku for example twice survived major bombing, involving a total of 9 1000 and 500lb weapons but returned to service. Four torpedoes did her in, but that would almost certainly lead to the loss of any WW2 carrier short of a Midway or maybe a completed Shinano.

Their's a lot of matieral written on the "paper" projections of the USN's defensive qualities, but cases of US battleships suffereing serious damage from enemy attacks post-Pearl are rare to non-existent. A lot of the kamikaze attacks on US BB's ended up doing little more than scratching the paint, but I doubt the BBs were often the kamikaze's primary targets anyway.

A lot of kamikaze attacks on everything didn’t accomplish much, see USS Laffey the ship that would not die (still afloat today). Can’t forget Franklin either, she wasn’t hit by suicide planes… but with more then twenty of her own bombs and a dozen Tiny Tim rockets exploding onboard that hardly mattered. It was like being hit by a whole payload from a B-17 and she still survived.

As for targeting, until after Okinawa BBs were the second highest priority suicide target after carriers. After Okinawa the Japanese decided to make transports the highest priority target, something they should have done from the onset, but never had a chance to put this into practice.

Kamikaze planes stuck at much lower speeds then falling bombs, and so they tended to inflict major damage on a ships upper works, without causing deep explosions which could cause flooding or machinery or magazine damage. This mean heavy causalities among the many exposed AA gun crews, but usually not that serious of damage, though still more then one ship was sunk by a single suicide plane.

The Japanese knew this and tried to counteract it by fitting rocket booster packs to increase dive speeds, and ordering pilots to release bombs just before impact, but neither was very effective. Japanese aircraft also simply typically only used small to medium sized bombs. Maryland actually took a hit from one of the Okha manned rocket bombs though, a 2,600lb bomb at 350mph, but it impacted a turret and caused only light damage.

[Ma Deuce]

For good examples of USN damage control in action, you'll have to widen your scope to more than just capital ships: Some can be found during the Guadalcanal campaign, the most outstanding in my opinion would be the USS New Orleans, which despite losing one-fifth of her entire hull (everything forward of the No.2 turret) to a torpedo hit that touched off her forward magazines during the Battle of Tassafaronga, she managed to stay afloat, and was later repaired and returned to service.

[Sea Skimmer]

I think the length lost on New Orleans works out to over 1/4th her length (around 150 feet from a less then 600 foot hull), including A turret! It’s an impressive survival, but one should remember she was able to anchor at Tulagi just 20 miles away for repairs. If she’d had to leave the area she would have almost certainly sank. The ability of the USN to seize and defended forward anchorages and create a whole fleet of repair and support ships was critical to the survival of many ships, and it’s just unprecedented before or since in warfare.

[An Ancient]

You also have to remember Pearl Harbour was an attack with aerial torpedoes which are usually less powerful than ship and sub launched varients. Overall, the older battleships had a faulty design in that their bulkheads were pierced and leaked badly, which as has been noted no damage control could fix.

[Sea Skimmer]

1941 Aerial torpedoes were weaker then 1941 sub and surface torpedoes sure, but actually they had warheads equal in power to the 400lb TNT charge most of the American battleships had been designed to withstand when built back in the 1912-1917 period. Most of the old ships had had some TDS upgrades since then, which don’t seem to have worked, while the newer ships had a higher 600lb standard of resistance which held up quite well. West Virginia was hit four times on her TDS and not one hit penetrated. Unfortunately she listed so quickly and before counter flooding could take effect that water came up over the top of the TDS, and then one or two torpedoes struck actually struck her deck. That did bad things to whatever water tight integrity. It also points to the problem faced by all ships that flooding within the limits of aTDS can still be heavy.

Interestingly the Japanese later (1944) fielded a world beater aerial torpedo with a 950lb warhead, essentially on par with the 1000lb warhead of the massive Type 93 ‘Long Lance’ surface torpedoes. Meanwhile Type 93 had its own warhead upgrade which went up to 1,700lb, at the expense of about 10km worth of not very useful range. Nothing could withstand such blast. Even Yamato was only rated against 852lb of TNT equivalent, and the TDS on all three ships of the class had the chance to failed against 600lb torpex charges. The RN made a ridiculous claim for 1,000lb resistance on KGV, only to see the TDS on Prince of Whales beat by a 441lb warhead, while even the big beamy war experience based Malta and United States class carriers only claimed around 1000-1,200lb TNT resistance. But then, everyone already knows building a bigger weapon is easier then building better armor.

[An Ancient]

1941 Aerial torpedoes were weaker then 1941 sub and surface torpedoes sure, but actually they had warheads equal in power to the 400lb TNT charge most of the American battleships had been designed to withstand when built back in the 1912-1917 period. Most of the old ships had had some TDS upgrades since then, which don’t seem to have worked, while the newer ships had a higher 600lb standard of resistance which held up quite well. West Virginia was hit four times on her TDS and not one hit penetrated. Unfortunately she listed so quickly and before counter flooding could take effect that water came up over the top of the TDS, and then one or two torpedoes struck actually struck her deck. That did bad things to whatever water tight integrity. It also points to the problem faced by all ships that flooding within the limits of aTDS can still be heavy.

True, but I don't think they ever solved the problem of the bulkheads being far to heavily pierced to be called properly watertight.

Interestingly the Japanese later (1944) fielded a world beater aerial torpedo with a 950lb warhead, essentially on par with the 1000lb warhead of the massive Type 93 ‘Long Lance’ surface torpedoes. Meanwhile Type 93 had its own warhead upgrade which went up to 1,700lb, at the expense of about 10km worth of not very useful range. Nothing could withstand such blast. Even Yamato was only rated against 852lb of TNT equivalent, and the TDS on all three ships of the class had the chance to failed against 600lb torpex charges. The RN made a ridiculous claim for 1,000lb resistance on KGV, only to see the TDS on Prince of Whales beat by a 441lb warhead, while even the big beamy war experience based Malta and United States class carriers only claimed around 1000-1,200lb TNT resistance. But then, everyone already knows building a bigger weapon is easier then building better armor.

Actually the RN had some good reason to claim the KGV's torpedo resistance. I'll dig up the relevant book by D.K. Brown tommorow, but apparently what did the PoW in was an unlucky torpedo hit to a shaft, which bent and then ripped itself apart, flailing open a huge part of the hull as it did so, dooming the ship.

[CaptHawkeye]

I'd heard the TDS on the Colorado/Tennessee was a paticularly unique system. It was apparently far better than the defenses of Pennsylvania.

I'll be fair, Pennsylvania WAS torpedoed in a very inconvienent place -the far stern- which as far as I know no TDS could really protect a ship in that area.

[Kitsune]

The Colorado/Tennessee had Turbine Electric Engines which allowed for excellent subdivision.
Before "An Ancient" brings it up, there was a potential problem with losing a bus but no matter what you build, a design will have weaknesses.

One problem though with the Colorado/Tennessee was that by the time of Pearl Harbor, they were overweight and too much of the belt was underwater. Even before the war, the intention was to bulge the entire big five.

[Sea Skimmer]

I'd heard the TDS on the Colorado/Tennessee was a paticularly unique system. It was apparently far better than the defenses of Pennsylvania.

It was unique for the time, but it was copied by other nations, and it was a big improvement of anything that came before it. All later US TDSs are based on similar ideas

As built Pennsylvania had only a single real layer of protection, a void, with a single thick layer of armor on a bulkhead to form it, and then a second cofferdam bulkhead behind to protect against minor leaks through the armor. It was rated against 300lb TNT. New Mexico increased the depth of the system and added another bulkhead to create three voids total, but kept the single thick armor layer.

What Tennessee introduced was a system based around multiple thin elastic armor bulkheads that would tear instead of shatter like a single thick one would. A total of five bulkheads, the middle three armored, were used to create a five layer system (sixth surface is the hull) with the middle three layers filled with liquid.

In the 1920s most older battleships including the Pennsylvania and New Mexico classes were rebuilt to incorporate these new ideas. However because of the difficulty of rebuilding a ships guts like this, and a lack of beam, it was usually only possible to make the systems have three or four layers, plus an additional layer from the blister (many ships were blistered between wars, just not to a sufficient extent, and they added lots of deck armor weight at the same time). In addition the spacing between layers was often not of equal distances, a key feature Tennessee. The earlier ships also had sloped armored decks joining the bottom of the belts, which limited the height of the TDS compared to Tennessee, which was the first ship with a completely flat main armor deck carried above the design waterline to attach to the top of the belt.

Now when the US started building fast battleships, some things changed for various reasons. Five layers were kept, but the bulkheads were angled so the system became wider the lower in the hull it went (deeper running torpedoes transit more blast energy thanks to water pressure). In addition it was found that the outer void layer was ineffective, and was replaced by another liquid loaded layer. A void was retained only inboard. Also, the USN became concerned about shellfire diving under the belt at long range. The USN didn’t know it, but Japan had actually designed all of its modern APC shells to do exactly that too, abet without great reliability. This meant that at least one thick layer of armor had to be in the TDS, even if it meant sacrificing torpedo resistance.

North Carolina only had small patches of thicker armor over her magazines because this danger was realized late in her design process, while South Dakota and Iowa extended the sloped belt to almost the bottom the hull, abet with heavy tapering. Montana would have used a separate and further inboard armor belt to accomplish the same task, reducing the chances that a torpedo blast would reach the thick armor and convert it into fragmentation. Since none of the Iowa’s or South Dakota’s were torpedoed, we don’t know just have detrimental this armor would have been for torpedo resistance.

I'll be fair, Pennsylvania WAS torpedoed in a very inconvienent place -the far stern- which as far as I know no TDS could really protect a ship in that area.

Its plain impossible. You just don’t have enough beam in the ship in the stern or bow to add a TDS, never mind the weight penalty which would drag down the ships ends or the need to use the volume for other things. Pennsylvania was hit by a big aerial torpedo, and also had the disadvantage that because she was so lightly damaged at Pearl harbor, she never got a big wartime rebuild like the heavily damaged ships did. This left her with inferior watertight integrity and less damage control capability compared to other battleships by 1945.

However while the 3000+ tons of flooding she took was considered heavy, and it was, its interesting to note that when even mighty Yamato was torpedoed in 1943 on her TDS, one of the thickest parts of it no less, it failed and allowed flooding into the 155mm magazines. Total flooding in this case was also around 3000 tons. This was because Yamato had an awful TDS design, and awful subdivision (battleship Nagato, a ship half the displacement, had 85% as many watertight compartments) but it goes to show that any ship was going to be at risk from WW2 torpedo warheads.

In general, TDSs just plain tended to fail more often then they succeeded, even when hit by warheads below the designed strength. West Virginias TDS withstood four hits, but that just wasn’t typical at all. Besides Yamato we can also look at Bismarck, which had its crappy TDS fail against a 385lb warhead torpedo (design spec was 550lb), and as I recall one of the Essex’s that took a torpedo also had its system fail against much less then its designed resistance despite being of an excellent design. Blast pressure will exploit every weakness, it inherently finds them, and even the best TDS still has to be bolted and welded together, as well as having access manholes and piping running through it.

[An Ancient]

Just in case anyone's interested, I did some digging, apparently the Nelson and KGV class were designed to resist 1000lb warheads, and full scale tests against their protection were conducted using the then-secret 'Job 74' full scale rig. These schemes held up to the blasts and Nelson's was thought to be able to take even larger hits. (Note: It is however considered that the test's represented 'ideal' conditions).

PoW's death to the Japanese bombers was possibly even worse luck than the Bismarck's, Out of the first four torpedo hits, two hit propeller shafts (one on each side), in both cases causing distortion and fracturing which then ripped open huge areas of the ship as the shafts spun off. One hit one the proper protection did diddly squat and the fourth also hit the protection, but in an area where the air-filled spaces had been counter-flooded to correct the existing list, so served almost no protection. At that point it was doomed.

[Kitsune]

From a military discussion board:

- You will find many people claiming different things for US versus British Torpedo/Side Protection systems. Some things to bear in mind ;
--- Due to scaling effect the British figures (pre-Vanguard) are 30% or a bit less overstated. So where a 1935 system is quoted as proof against 1000 lbs of TNT, it should really read 770+ lbs of TNT.
--- One has to look at the full "system"
--- From mid to late war better explosives were used in some torpedoes
--- Late war/post war it was discovered, researched and modelled that "discontinuities" were awful things to the integrity of side protection systems. I can find that, or similar phrases, in large numbers of naval research reports and design papers. Nowhere can I find any sensible explanation - I will leave that to others.
--- In any system where exactly the torpedo hit mattered - the system did not react exactly the same for a hit even slightly differently placed.
--- Apart from that, at least for British systems, the figure quoted is a true minimum. The British tended to "tweak" the system along its length and widths changed. So, for instance, Vanguard's system had places where it was proof against 1000 lbs, and places where it was over 1400 lbs.
---- As late as the CVA-01 design (1964) the British and US Side Protection Systems (they compared designs and tests with the latest USN attack carrier design) were very different in concept whilst both protected against the same amount of explosive. There was and is not just "one way" to do these things.

Second, from an official British report comparing US and British Caisson tests regarding the Midway and Gibraltar designs. The two teams exchanged almost all the design features. The British realised that their model scaling factors had been wrong. Even on the full-sized tests there were difficulties. But again, there was an awful lot of discussions about the detailed design of joints and structures.

[Sea Skimmer]

Just in case anyone's interested, I did some digging, apparently the Nelson and KGV class were designed to resist 1000lb warheads, and full scale tests against their protection were conducted using the then-secret 'Job 74' full scale rig. These schemes held up to the blasts and Nelson's was thought to be able to take even larger hits. (Note: It is however considered that the test's represented 'ideal' conditions).

DK Brown indicated that the design simply failed to live up to expectations; he suggests this may have been because the charges were not detonated at a sufficient depth under water. Full scale Job 74 trials also indicated the system on Ark Royal should easily withstand 750lb, and yet a single torpedo of lesser weight flooded multiple inboard compartments, and indeed caused enough damage that even the centerline boiler room immediately began to flood. She might still have been saved, but it seems watertight integrity in general just sucked, and of course, she had no auxiliary power and totally inept damage control.

Later the RN designed a system to repel 2,000lb charges for what became Malta based on earlier trials, but when tested full scale it failed against a 1,000lb charge. After further redesign work, the system was finally considered proof against 1,200lb. It was 25 feet wide, nearly 2.5 times that of the ‘1000lb proof’ narrow system on KGV. This is not a big vote of confidence in KGV protection. The USN for its part used a 22 foot wide system to withstand 1,200lb on United States.

So yeah, no one really knows how the Job 74 trials were screwed up because few records survive but no doubt can exist that they overvalued protection.

PoW's death to the Japanese bombers was possibly even worse luck than the Bismarck's, Out of the first four torpedo hits, two hit propeller shafts (one on each side), in both cases causing distortion and fracturing which then ripped open huge areas of the ship as the shafts spun off. One hit one the proper protection did diddly squat and the fourth also hit the protection, but in an area where the air-filled spaces had been counter-flooded to correct the existing list, so served almost no protection. At that point it was doomed.

Four torpedo hits have been confirmed; by a hull search in 3 foot visibility and extreme diving conditions. A true picture will have to wait until someone scans the wreck with high resolution sonar. I don’t know why that wasn’t just done in the first place, given that such sonar’s are now precise enough to show individual rivet heads. I guess they just didn’t have enough funding for it.

The RN for its part places the number of hits at six, at least two of which did defeat the side protection, one in the counter flooded area, and another in an intact area which while not openly rupturing the holding bulkhead did cause it to leak and flood an auxiliary machine space, the first of many blows against the ships electrical generating capacity.

However no torpedo hit does squat, at the least a hit will flood the TDS over a distance as great as 100 feet, causing significant flooding and comprising protection. Even duds have inflicted significant damage on ships, usually destroyers losing a bow or stern, and sunk one or two through shear momentum of impact. On its own flooding in the TDS from one hit will not matter, but it can easily become the tipping point that makes the different between a ship sinking and remaining afloat when other damage comes into play. If numerous torpedoes hit rapidly together, as happened to West Virginia, then the damage can induce a sever list.

Prince of Wales like Ark Royal also seems to have suffered from inherently poor watertight integrity, which allowed the rest of the auxiliary machine spaces to flood. She has a slight excuse though, since the ship was actually struck by bombs during construction and was generally rushed into service. But then RN ships were at least cheap, the USN ones had much better fittings but may have cost as much as double in some instances.

---- As late as the CVA-01 design (1964) the British and US Side Protection Systems (they compared designs and tests with the latest USN attack carrier design) were very different in concept whilst both protected against the same amount of explosive. There was and is not just "one way" to do these things.

This is not a very supportable claim, or at least the author is going too far. Both US and British systems were based around sandwiching liquid loading with void spaces and with relatively thin armor, using vertical or near vertical bulkheads. The details could and did vary even within each navy, but the concepts are quite the same. Some nations DID use truly different concepts, such as the Italian curved bulkhead Pugliese system, and Japans all void + ridged armor system, and these failed miserably in combat.

Late war and postwar the RN began making its systems and particularly liquid loaded spaces wider, often radically wider in line with US practice, while the US began using narrower voids as the RN favored. Both nations also abandon the outboard void spaces as ineffective.

[Kitsune]

Prince of Wales like Ark Royal also seems to have suffered from inherently poor watertight integrity, which allowed the rest of the auxiliary machine spaces to flood. She has a slight excuse though, since the ship was actually struck by bombs during construction and was generally rushed into service. But then RN ships were at least cheap, the USN ones had much better fittings but may have cost as much as double in some instances.

How much of this was due to greater water tight integrity and how much of this was due to constructed the whole ship from simply higher grade STS steel?