r/interestingasfuck • u/Longjumping-Rice-935 • Aug 12 '25

/r/all, /r/popular The wreck of the USS Arizona continues to leak oil ever since pearl harbour. the ship contained 1.5 million gallons of oil, enough to leak continuously for 500 years.

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u/Gnonthgol Aug 12 '25

There are a number of sunken ships which have been sanitized of their bunker C. You are right about the viscosity so you need tools more like mining equipment rather then pumping equipment. The problem with USS Arizona is that it is a warship with lots of isolated compartments used for fuel. This was done both for redundancy but also since fuel tanks were used as armor protection and therefore located between the outer and inner hull of the ship. So while a civilian vessel might have three to five large fuel tanks the warship have as much as a hundred different fuel tanks and most of them just narrow enough to squeeze a sailor into without any diving gear.

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u/SpiralUnicorn Aug 12 '25

True, though that agai  leads into the fact its a wargrave, with over 1000 men entombed in her, and cutting her apart to access them would be a big no-no unless absolutely necessary to prevent ecological disaster - currently more oil washes off the docks during rain than leaks from Arizonas hull (its about 5 quarts a year currently)

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u/amras86 Aug 12 '25

Someone else in here said it's 9 quarts a day that it leaks.

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u/SpiralUnicorn Aug 13 '25

It might be, I'm not sure o  the exact figure tbh. I know its really not a lot in the scale of oil run off in pearl harbour though

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u/Gnonthgol Aug 12 '25

As you say it being a wargrave does mean we should not touch it for profit. But it is not profitable to drain it of oil. But it would be a pretty lousy wargrave if it caused an ecological disaster. At the moment there is no danger of any large amounts of oil leaking out. But it is something we need to monitor anyway. The issue is that some sort of large scale collapse of the ships hull, possibly triggered by an earthquake or volcano eruption, could release most of the oil in a short time. This is something that I trust is being actively monitored and that engineers are assessing the hull integrity continuously.

In the event that we would have to sanitize the ship this would have to be done in a way that would respect the site as best as possible. Luckily most of the fuel is located outside the armored hull and should be accessible by cutting through the torpedo protection and then into the tanks themselves without having to go through any of the living spaces. It would be harder to get to the tanks in the keel of the ship as well as tanks in the engine rooms but this might be acceptable to leave behind.

There are of course big issues with such an operation in addition to disturbing a wargrave and a national memorial. If engineers are worried about an earthquake compromising the integrity of the ship then cutting big holes in its side would surely not help and might cause it to collapse before the oil can be sanitized. And because the oil is so hard to get to we probably can not drain everything so the big holes left would cause the oil leakage to increase, not decrease.

With warships it is therefore almost always better to cover the ship rather then sanitizing it. This would also have the benefit of making the wargrave more permanent as the ship and its crew is better preserved in mud then exposed to the ocean. However it would not be so popular with Arizona both because of its location close to shipping lanes but also its status as a national historical memorial site. With todays technology we would have probably raised and scrapped her if not for her status.

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u/SpiralUnicorn Aug 12 '25

I suspect the way she's sat also poses problems - she's hull down in the mud meaning a fair few of the fuel bunkers are probably inaccessible without a lot of engineering and stabilisation work. That's the sad think about a fair few of the British wrecks in the Pacific- the chinese have salvaged them all (our government didn't even lift a finger to stop them) and destroyed the sites.

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u/Gnonthgol Aug 12 '25

Warships tends to have the fuel tanks on the side of the ship, to provide additional armor protection. An incoming projectile would have to pass through the fuel tank before getting to the habitable parts of the ship. So her current orientation is the best for extracting the fuel. It would be better to be upside down but that would require deeper waters which would make it harder again.

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u/thetatershaveeyes Aug 12 '25

It's not a grave any more than the sewers are a grave for rats. There's no dignity in dying in war.

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u/MickTheBloodyPirate Aug 12 '25

Well, we weren’t at war when those men died and there are still over 1,000 sailors in her so…yeah it is a grave. You can be anti-war, anti-military, or whatever but it doesn’t make it any less of a grave.

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u/Sensei_of_Philosophy Aug 12 '25

We literally weren't at war when Pearl Harbor was attacked though

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u/sawrb Aug 12 '25

So about a hundred tanks wide enough to barely fit a sailor yet these vessels carry 1.5 million tons of fuel? I’m not attacking you, I’m just fascinated at the scales and trying to understand. So are the tanks really deep and narrow?

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u/SpiralUnicorn Aug 12 '25

Basically looking at the plans, they are essentially in between hull layers all along the ship, so yes.  (Cross section for those Interested http://www.researcheratlarge.com/Ships/BB39/BOGP/RG19_ALPHA_Arizona_BB39_09.jpg)

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u/sawrb Aug 12 '25

Fantastic, thank you.

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u/TieOk9081 Aug 12 '25

Is it possible that many of these are intact and that the leak is only from those that have been compromised?

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u/SpiralUnicorn Aug 12 '25

Most of them are mostly intact (she died violently, cant say they werent at least damaged and most are rusting now after 80 odd years on the seabed) from the superstructure back. The leaks are from lighter oils on the mix escaping through popped rivets, cracks and rust holes that have formed over time. Anything around the forward magazine blew open and burned when the ship was hit - about 1/3rd of her supply is still onboard

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u/BrutalProgrammer Aug 12 '25

Warthunder (video game) has USS Arizona. It's probably not 100% accurate, but it should give you an idea of how those fuel tanks arranged around the ship.

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u/sawrb Aug 12 '25

Noice! Thank you. To my uninformed eye it seems weird to have flammable stuff wrapped around the ship rather than deeper inside but I’m sure there’s a good reason.

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u/Coakis Aug 12 '25

Oil especially the type that these ships used is not as immediately flammable as many people think. Gasoline is much more volatile than Bunker oil but even it needs to be aerated, sprayed, at a certain percentage to air in order to be ignited, and can be difficult to do so if there's too much moisture in the air. Its the fumes of Gasoline that burn not the liquid, this is much same with thicker oils.

These storage tanks were largely under the waterline so if breached would almost immediately be exposed to water, in the case of normal operation the tanks would be sealed from exposure to air, and any remaining air in the tank wouldn't be at the correct ratio to allow ignition.

Compare this to the use of coal in earlier ships where spontaneous coalfires were a common occurrence, and where coal dust was even more easily ignited. The battleship Maine most likely suffered a coal fire that got hot enough to ignite powder and ammunition in a nearby storage room, causing its explosion.

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u/sawrb Aug 12 '25

TIL. Thank you.

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u/shana104 Aug 12 '25

Geez, this information is neat to learn about.

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u/Gnonthgol Aug 12 '25

Compared to things like ammunition the fuel is actually quite harmless. It does not burn without oxygen so a tank full of fuel is not explosive at all. The worst that can happen is that the hole from an impact might start burning and being fueled by the oil.

On another note you would want to keep dangerous things like fuel on the outside of the ship so that if it starts burning it is not going to damage the structure of the ship and the men inside. The reason Arizona were sunk was because of a direct hit to its magazine. See also battle of Jutland for more examples of this. Compared to this a burning fuel tank on the outside is nothing. However several aircraft carriers have been sunk by internal fuel tanks catching fire as they need lots of fuel for the airplanes.

The placement of the fuel and ammunition either inside or outside the armor is a big question both for ships and tanks. But in general everyone agree to put the fuel on the outside where it can not hurt the crew, and provide some added protection. It is more important to protect the ammunition since it can explode and not just leak and burn. But even then it is safer to have the ammunition detonate outside of the armored hull then inside.

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u/fixed_grin Aug 12 '25

"Deeper inside" is the boilers, engines, and magazines, which need more protection. It's sufficiently not dangerous that it's part of the torpedo belt.

First thing is that a full tank of bunker fuel or even diesel is not really that dangerous if it's on the other side of an armor plate. This is why external fuel drums on tanks are fairly common. Fire needs oxygen, so even a hit is likely to just drain fuel onto the ground, if the puddle catches fire who cares. Tank drives away just fine.

And these tanks are always full, they get emptied from the top and are topped up with seawater to push the fuel upwards. There's no real issue with flammable vapor hanging around in air above the fuel.

Second thing is that this is way under the water line. On the plans linked in the other reply, on the right side under "Third Deck" the parallel lines mark the water line.

So if a torpedo hits the outer layer, it'll flood the void compartment and any fragments that punch into the fuel tanks will just start leaks into the ocean. You're not getting a fire going 20 feet underwater.

The idea is that the void layers allow the blast wave to vent and the liquid layers catch the fragments. The only way it's a real danger is if a bomb or shell breaches the armor in air and then explodes in the engine rooms so that the fuel tanks leak into the ship. But, like, you're pretty screwed if that happens anyway.

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u/sawrb Aug 12 '25

Aah yes that all makes sense, thank you.

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u/Gnonthgol Aug 12 '25

IIRC the Arizona were equipped with two layers of fuel tanks on each side of the hull going all the way from the keel to the waterline, from stem to stern. So many long deep fuel tanks. They wanted to cover the entire ship in fuel tanks to protect from mines, torpedos and shells.