375 atmospheres: I wanted to visualize what the ocean depth pressure might be at Titanic depth, but it isn’t easy to imagine.
Picture the entire weight of a Ford Expedition – about 5500 lbs – resting on a single square inch. Way more pressure than the bite of a Great White Shark or a T-Rex on that spot. It would push through solid oak as if it were pudding. There are materials that can take that kind of pressure, but structures that can do it are another matter.
With me so far? OK, now imagine that much pressure… on every single square inch of the outside of a structure. You’d multiply the pressure times the number of square inches to get total load on the structure.
A conservative, literal back-of-the-envelope calculation of the sub’s surface area gives us eighty-two thousand, five hundred eighty four square inches. And each one of those has a Ford Expedition resting on it – about 5500 lbs. For a total structural load of two hundred twenty thousand, one hundred six tons of pressure.
It gets worse.
The structure must not only be able to hold that tonnage; it must also hold its shape so the seals keep… sealing. And everything electronic outside must be protected from that pressure as well. (Usually this is done by filling it with an incompressible oil.) This includes sensors, batteries, lights, communication gear, and electric motors. That’s how you get stranded on the sea floor.
The sub is more or less cylindrical, with a sphere at the ends. This keeps structural load as even as possible. If the sub distorts a little bit, not only might the seals stop sealing, but it may fail structurally. If that happens, it will be fast; the sub will crumple in an instant, squashing its inhabitants to jelly. This is called ‘implosion;’ They would literally never know what hit them. Which could be a mercy.
- Real Engineering’s author is an expert in fiber-composite engineering, and he has thoughts on “The Questionable Engineering of Oceangate”
- People magazine: Get an Inside Look at OceanGate’s ‘Titan’ Submersible: Photos and Details
- Scientific American: See How Crushing Pressures Increase in the ocean depths
- IFLScience: What Is Implosion and how is it different from decompression?
- New Yorker: The Titan Submersible Was An Accident Waiting To Happen
- Why OceanGate Titan Imploded – A Carbon Composites Perspective
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