I assume the metal and materials the boats are made of are strong but surely not to withstand the pressure of being 12,000 feet underwater? At the end of the day it’s not like the engineers had to consider holding up to that much pressure in their design right?
In: 495
Oh, they do, but not the way you think. All the rooms of the Titanic that might have held pressure were either breached – individually, one after the other – on the way down by the rising pressure or weren’t sealed enough from the beginning, so that water could flow in.
The individual pressure-holding rooms or voids (of which there aren’t that many in comparison) don’t all immediately implode at the same time in one giant event.
The empty ship isn’t a sealed container. The water pressure fills the ship instead of pushing on the sides. If the vessel wasn’t sealed the pressure would build up and start pushing inward trying to find a leak.
A bunch of one end of the ship is crushed flat because it didn’t fill with water before getting deep
Equal pressure both sides of the steel plates. Submarines crush until the pressure equalises both sides of the structure.
There’s nothing left to crush. For it to sink all the spaces would be completely filled with water.
Things get crushed when external pressure is more than internal pressure + structure strength AND there’s no other way for the external force to get inside (read: air/water tight)
If the external pressure can force itself inside through a breach it will do that first as that is easier/less resistant. Eventually the pressure will equalize and there’s no more risk of crushing.
The titanic was filling up with water and had a rather massive breach, which became even bigger when it split in half. Water would have rushed into every opening available, equalizing the pressure very quickly.
The only things getting crushed now would be the metal itself and other structures, but there’s only so much those things can shrink.
Say you are pushing on the wall in your house.. eventually the strain would make the wall buckle and you go right through (submarine)
Now instead someone else is on the other side of the wall pushing with the same exact force as you. There will be a small amount of compression of the material that makes the wall but largely the 2 forces are now equal and opposite so they cancel each other out (sunken titanic)
That’s not to say that things didn’t buckle as the Titanic went down.. anything that was air tight at the time of the sinking could and probably did either suffer a catastrophic implosion or eventually suffered a breach and also filled with water
The pressure is equalized as a regular ship takes on water. Essentially, the ship sinks while taking on an inch of water at a time..
It doesnt add pressure.
If youre talking about the titanic submersible, its a pressurized cabin, and is also built in a rounded design, to keep the hull in a state of maximum crush-proofness. Not a word but I am using it.
Idk if the cabin can lose pressure if the systems went down. It was already pressurized so it wouldnt lose pressure unless there was a breech.
Also a teacher, but early elementary lol
Think about a soda can.
When it’s full, the inside is pressurized. That means there is MORE air pressure inside than outside. So when you try to squeeze it, that internal pressure pushes back against your hand. If you squeeze harder than that pressure, you’ll crush the can, but it’s really hard.
When it’s empty, that pressure is gone. The inside has the same pressure as the outside air. So when you push with your hand on the outside, there’s nothing inside pushing back that hard and the can is crushed easily.
The Titanic is open like the can. But the water pressure isn’t like your hand. The water on the “outside” of the Titanic has the same pressure as the water on the “inside” of the Titanic. So while water is pushing one way on the “outside”, there’s other water pushing the opposite way on the “inside”. If the Titanic were made out of a material that can compress like Styrofoam, it’d shrink due to all of this pressure. But it’s made out of metals that don’t really compress that way. They’re under a lot of stress, but they can take a lot of stress.
The submarine is a case where it’s more like we took some air out of the soda can and re-sealed it. Now the air on the outside is pushing HARDER on the can than the air inside. But the can’s metal still has some strength and can withstand some of that stress. If the outside air pushes harder than its ability to resist stress, the can will implode.
> At the end of the day it’s not like the engineers had to consider holding up to that much pressure in their design right?
Yes, they did. And one engineer had concerns. He was fired and is suing the company over it. [You can read a story here](https://newrepublic.com/post/173802/missing-titanic-sub-faced-lawsuit-depths-safely-travel-oceangate). I think this part of the story says a lot:
> Lochridge learned that the viewport manufacturer would only certify to a depth of 1,300 meters due to experimental design of the viewport supplied by OceanGate, which was out of the Pressure Vessels for Human Occupancy (“PVHO”) standards. OceanGate refused to pay for the manufacturer to build a viewport that would meet the required depth of 4,000 meters.
So the “viewport” of the sub was built to withstand water pressure at about 1,300 meters. The Titanic is in water at a depth of about 3,800 meters. That’s why the article mentions the required depth would be at least 4,000 meters. (I said “one engineer”, but that was just this article’s focus. If you really look in to this company, there have been many concerns from many people for a long time.)
This engineer saw, and reported, and knew everyone knew that the sub had materials not designed to handle the depths. The company responded to this by firing him. This is why it’s not good to trust eccentric billionaires who insist what they’re doing is safe and “sacrifices must be made”. They’re right an awful lot and when they are they advance science. But when they’re wrong, they’re catastrophically wrong. The problem is they tend to be right for a long time before the disaster happens, and they use that string of successes like a weapon to beat down people who raise concerns.
If you put a cup in water upside down so that the air is trapped, there is more pressure, from the water, on the outside of the cup than the inside of the cup. If you place a cup in the water so that it is full and basically just floating around, there is equal pressure on the inside and outside of the cup.
If a ship goes down that has leaks, water will fill it up and there will be equal pressure on the inside and outside.
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