Damage

== SES's Position on Brit Magazine Explosions ==
=== Summary ===
After exhaustive study of the issue of Brit magazine explosions in WW1, we have come to the conclusions stated below. This is essentially a restatement of the long section on magazine explosions found in the summary chapter of Campbell's Jutland: An Analysis of the Fighting. Of all that has been written on the subject, we think this is the best argument.
Brit ships blew up due to the extremely volatile nature of their cordite, which basically would explode (as in very rapid combustion releasing vast quantities of high-pressure gas in an extremely short time) even when not contained within the breech of a gun. In effect, the pile of cordite in the magazine was analogous to the filling of a shell, and the hull of the ship was analogous to the shell's body, becoming fragments when the filling exploded. The rapid build-up of gas pressure from the burning cordite ripped the ships to pieces.
This was in sharp contrast to the German propellant, which burned slower and did not release such huge amounts of high-pressure gas in such a short time. Thus, while German propellant would burn spectacularly, it was incapable of creating the over-pressures necessary to rip a ship to pieces.
Because all British ships carried the same cordite, all of them could potentially explode this way, even DDs. However, the only ships that suffered catastrophic explosions were those that were hit somewhere on or near their main turrets/barbettes. Thus, only Brit ships with main turrets are subject to the special "advanced critical hit" (ACH) that causes magazine explosions over and above the rare regular critical hit explosion that can happen to any ship on either side. That means ALL Brit BBs, BCs, and ACs, but nothing else, are subject to the ACH.
For most of the ships that exploded, witnesses observed hits on or near the turrets. It seems reasonable to assume that these hits penetrated the armor of the turret, barbette, or associated magazine. Therefore, in the game, the to cause an ACH explosion, the shell must not only hit the turret (which includes the barbette and magazine) but also penetrate it. Only then does the 20% chance of explosion come into play.
=== Discussion ===
=== 1. Why SES Believes Cordite was the Culprit ===
:In both WW1 and WW2, German ships had propellant fires inside their magazines yet did not explode. Brit ships did explode, apparently from propellant igniting in the magazines, but nobody survived to tell exactly what went on there. However, clearly the different outcomes strongly suggests a fundamental difference in the combustion properties of the 2 propellants.
:The best data on internal Brit cordite fires comes from Lion's Q turret at Jutland. There, 8 charges between the magazine and the turret ignited from a smoldering ember some minutes after the hit. The combustion was nearly instantaneous, effectively an explosion. Just these 8 charges created enough gas over-pressure to blow big armor plates off the turret above and seriously distort the magazine bulkheads and hatches below. The flash killed everybody still in handling rooms and even some people in the surrounding area, and produced a huge mushroom cloud seen in photographs. Campare this to Seydlitz at Dogger Bank, where a much greater propellant burned, some of it inside the magazines, yet there was no damaging over-pressue.
=== 2. Sloppy Brit BC Ammo Handling and Flash Protection Measures ===
:Many people claim that the Brit explosions at Jutland were the result of the BC gun crews keeping magazine doors open, having too much cordite out of the magazines, and otherwise circumventing what flash protection they then had. Further, they say that this would not have happened to the BBs in the "by the book" Grand Fleet. We, however, do not think this was a significant factor.
:In Lion's Q turret, the magazine doors were closed and the only the proper amount of cordite was out of the magazines. All of that cordite was also in approved positions, either cages or waiting boxes, with their flash protection in place. Yet not only did all those charges ignite anyway, but they created enough over-pressure to damage the ship's structure. In fact, this damage was enough to expose the contents of the magazine to flash, due to the distortion of the magazine bulkheads. Had not the magazine already been flooded, it seems highly probable that Lion would have blown up from this flash. Thus, even if all then-existing safety procedures had been followed, it would not likely have made a difference.
:Of course, the structural distortion of the magazine bulkheads was not necessary in 1916. Apparently at that time, Brit magazine doors were only flash-proof from inside the magazine going out into the handling room, but not going in from the handling room to the magazine. Thus, the ignition of a few charges somewhere in the barbette was capable of getting flash into the magazine even if the doors were closed, and even if the bulkheads weren't distorted by over-pressure.
:While this was remedied after Jutland, however, the distortion of the bulkheads caused by even a few charges in the barbette negated this. This distortion no doubt would also have negated other Brit flash protection improvements of later years, as well. All these scuttles and better cages and such were just thin sheet metal, easily capable of being twisted open by the gas over-pressure of burning cordite. You needed something as thick as a gun breech to contain a cordite explosion without rupture or distortion.
=== 3. Why Brit Battleships Can Explode ===
:This should be pretty obvious by now: BBs had the same cordite as the other Brit ships. This cordite, obviously, had exactly the same combustion properties in a BB as in a BC or AC. Also, the BBs had the same standards of flash protection as the other ships. If these safety measures would not have saved Lion, they would not have saved a BB, either. Had the Brit BBs ever come under effective fire, some of them certainly would have blown up, too.
:Therefore, the only advantage Brit BBs have over BCs in terms of magazine explosions is thicker turret armor. This will reduce the number of turret penetrations they will suffer, which means they have fewer chances of having an ACH explosion. However, most Brit BBs had only 11" on their turrets (compare to 9" on the "Splendid Cats") so would do well to engage at long range.
== Damage FAQ ==
IIRC at Campbell I read that on one British ship a hit on the secondary batteries nearly caused a magazine explosion too, but the chance of this happening should of course be much higher with the main turrets. 
Historically, the Brits were extremely worried about 2ndary ammo leading to explosions, much moreso than they were about main turrets. This is understandable, because the main magazines were the best-protected things on the ship, while 2ndary ammo was often quite exposed. However, during the war, no ship blew up from 2ndary ammo fires while quite a few did from main turret hits. That can't be just coincidence, because there were many more hits on 2ndary batteries and CL gun decks (essentially the same thing for purposes of this discussion) than there were on main turrets, and many of these hits caused serious propellant fires. Thus, despite appearances, 2ndary/CL ammo fires must have been fundamentally less likely to blow up the ship than main ammo fires.
In most Brit capital ships, the 2ndary magazines were at the ends of the ship adjacent to the main magazines. Thus the hoists came up near the end main turrets, from whence the ammo had to be carried the length of the battery. The main guns of CLs on both sides were fed the same way. Alternatively, the magazines were still at the ends but there were multiple hoists near the guns supplied by ammo carried along below deck through the "ammunition passage", which ran the length of the battery. Either way, you had what looked like a long powder train running the length of the battery, composed of ready use cases and exposed bag charges, leading to magazines. You can thus see why the Brits worried a lot about fires anywhere in the batteries reaching the magazines.
However, that never happened, despite a lot of bad fires in batteries and CLs. In most cases, the fire didn't spread the length of the battery, but only involved 1 or a couple of guns. Thus, there often wasn't the continuous powder train the Brits feared. This was no doubt because these areas were well ventilated to the atmosphere, either by being on the open deck or by having skylights, large gun openings, and such. Thus, most of the heat and flash could go upwards (as it wanted to do) and outwards, leaving the ship, instead of being constrained to go sideways along the battery (this is the same reason firemen often cut holes in the roofs of burning buildings). This venting also prevented the build-up of ship-tearing over-pressures.
In a couple of cases, burning debris from a fire in the battery went down hoists, either into the handling room adjacent to the magazine, or into ammunition passage. However, people there were able to stamp these embers out before they ignited any charges. The fact that these people were still alive to do this indicates that no flash came down the hoists, and that no pressure came down, either. This supports the notion that the vast bulk of the conflagration in the battery vented up and away from the ship.
This is why we don't have an ACH for Brit 2ndary battery hits, or for hits on ships without main turrets. The bottom line seems to be that while the main turret armor protected the main gun ammo from incidental sparks and flash exterior to the turret, if that protection was ever breached, the huge amount of propellent in the main magazines would destroy the ship.
How`s the chance of German ships blowing up? Only by a direct hit to the magazine? 
German ships can explode, but only rarely. AFAIK, they have the same chance to blow up as any ship in the RJW--a fluke hit every now and then. The Brits always have this same chance in Jutland, too, even if you turn the ACH magazine explosions off. This covers the odd German blowing up (and a few did in real life), plus a very unlucky set of circumstances in a Brit 2ndary battery .
At the risk of getting off-topic (this thread is supposed to be about Brits), here's our take on German magazine explosions....
The German ships that exploded seem to have done so for the same reason that modern AFVs explode: the explosive in their shells detonated. German propellant simply did not generate the huge over-pressures necessary to rip ships apart.
Most high explosives (except for things like picric acid) are difficult to make explode. This is why shell fuzes have detonators in them, and why unfuzed shells are pretty safe even in fires. But if you have a stack of shells, the explosion of one of them can act as a detonator to the rest. Thus, to blow up a shell magazine, the easiest way is to trigger the fuze of 1 shell. And that's a LOT easier to do than cook off unfuzed HE. So, if there's sufficient shock, some shell fuzes can become armed, and then bounce around until they're triggered, and then KABOOM. There are, of course, safety features that try to prevent this, so it doesn't happen that often. However, this is apparently what happened to Pommern, and it nearly happened to Konig. While cleaning up the mess in a 2ndary magazine after Jutland, wrecked by an underwater shell hit, the Germans found a shell with an armed fuze under the debris.
FWIW, I've see dozens of AFVs have magazine problems, and have caused a few of those problems myself . Most of the time, the propellant burns in a big POOF that makes a quick fireball. This leaves all the flammable material like insulation, clothing, seat cushions, etc., burning, as well as sometimes the fuel tanks. But the tank is usually structurally intact, although the turret might be lifted a little. But every so often, the HE shells explode, too. This is what makes the turret pop off and sometimes breaks the hull up as well.
German propellant charges were encased in metal, while the British kept theirs in silken bags - makes a much quicker fire. 
Actually, for German guns of 28cm and above, the charge was too big to handle in 1 piece, so these guns had part of the charge (the amount varied by gun but averaged about 1/3 of the total) in silk bags just like the Brits. This was called the fore charge because it was ahead of the main charge in the cartridge case. These fore charges were obviously more likely to ignite than the main charges in the cartridge cases. However, even the main charges just had cardboard or something similarly flammable and flimsy over the front end, so they were also somewhat vulnerable to flash.
Campbell says how many of each type were involved in the various German propellant fires. Usually, it was more fore charges than main charges. IOW, when the Germans had big fires involving way more propellant than Lion's Q turret, at least 1/2 and often a bit more of it had been in silk bags, just like Brit propellant. Thus, the use of cartridges really didn't make the German big gun ammo system any less prone to burn. Where the cartridges made a difference was for the 2ndary guns. Most Brit capital ship 2ndary batteries were BL, but all the Germans were QF.
I watched a Discovery Channel documentary on Jutland where among other things, they measured crudely the rate of propogation of cordite flash. Now I do not remember if they had WWI cordite. As I remember they came up with a burn rate of 600ft/sec in a tube. That seems awfully fast to me in comparison to black powder which burns at 560-2000 ft/sec when confined. 
I saw that show. They didn't have WW1 cordite, they had modern arty propellant, which is way better behaved. It's very similar to WW1/2 German naval propellant. It burns like crazy, but not as fast as cordite.
I saw another show where they went down to Majestic's wreck off Gallipoli and brought up some genuine WW1 Brit cordite. The wreck is covered with it from the ship capsizing and spilling charges all over, and the silk bags rotting away. Anyway, this stuff had been immersed in shallow sea water for about 90 years. It still ignited very easily and burned with a bright white flame that threw huge sparks all over, but it didn't burn very fast. It was like the guy was holding a giant holiday sparkler. He had to toss it over the side in self defense, and it continued to burn underwater as it sank. I've often wondered how it would have gone if he'd still been directly over the wreck Or what would have happened if he'd let it dry out for a couple of days before lighting it.
Will a ship like HMS Agincourt with 7 twin turrets be more likely to suffer a turret hit (and hence the following KABOOM if it penetrates) than a ship with fewer turrets? Assume armor is the same. I've often thought Agincourt was a multiple magazine explosion just waiting to happen. 
Yeah, I'd say Agincourt's more likely than anything else to get hit in a turret. OTOH, she's got 12" turret armor instead of the usual Brit standard of 11", so it's something of a trade-off. Of course, her value is somewhat limited due to lacking a director and the fact that the rest of her is armored no better than Lion.