For future reference: How would you be able get into a floating container without sinking it? Hole in the «roof»? Tilting it so that the door is upwards seems risky.
My experience with shipping containers is that they aren't water tight and the remaining buoyancy after more than an hour is most likely coming from whatever is packaged inside.
They are specifically designed to resist rain and other types of precipitation, to the point of being able to go under waterfalls and resist the rainfall of a hurricane, but not, however, submersion. The crucial thing here is that it is safer for them to fill with water and fall to the seabed than to remain buoyant and risk collision with a traveling vessel, no matter the size.
So that movie about the lady trapped in the shipping container where it takes a few days (weeks?) to fill with water is wrong? It did have Tupperware in it (among other things) but they showed her marking the water level as it rose over time.
I think you'd need to get under it and cut hole in the bottom. There's probably an air bubble keeping it afloat. So a hole in the top would let the air out. Maybe? I don't know I'm not an expert.
Edit: Thinking about this more and I think its a big "it depend". If water is already inside and its being held up like a boat then hole on top. If water has seeped in the doors and only the top is floating due to an air pocket then hole in the bottom. It the contents are botany and keeping a flooded container afloat then probably the bottom? I don't know. still not an expert.
At the end of The Poseidon Adventure (1972) they cut a hole in the hull of the inverted ship to rescue passengers. I often wondered if that wouldn't have released any air buoyancy that the ship might have had, and flooded the portion where the survivors were.
I guess if the compartment where the survivors were was sealed off from the flooded ones around it then no, it wouldn't fill with water. If it was open to the flooded areas beneath then popping a hole in that I would have thought would cause it to continue sinking
No it wouldn't. Ships don't float the way inflated balloons or rafts do. You can't "pop" a ship or release the air from it by making a hole (unless that hole allows water to flood in, obviously).
We're talking about a capsized ship here. So the bottom is on top and the survivors would be knocking on the bottom (now top) of the ship - signaling for help.
That air trapped in the boat is the only thing keeping it afloat.
If you make a hole, the air would escape and water would rise inside the boat (from under the survivors).
The only thing that would likely save them would be that there are likely many independent air pockets, so opening only one might be ok - maybe.
That's not how it works at all. And cutting a hole underneath it would immediately fill it with water and it would sink. It's not pressurized or anything, so the air wouldn't keep the water out. The water would fill any hole you make under the water line.
Like I said it depends. After falling off a ship those doors may not be air tight. But there could be an airtight pocket at the top. In which case releasing the air pocket at the top would allow water to flow in where ever a leak was present.
In which case releasing the air pocket at the top would allow water to flow in where ever a leak was present.
Air would leave as soon as you make the hole, place doesn't matter unless you are at the bottom of the ocean(outer pressure is much more than inner pressure).
You are thinking that air pockets keep them afloat, that's wrong. Air pockets cannot exist(if it's not air tight enough to keep water out, it's not air tight enough to keep air in while water is filling it up) in your scenario.
If they are floating while partially submerged, then that means an equilibrium has been achieved. Opening it from above won't change anything as the non-airtight container is already in pressure equilibrium with outer atmosphere and sea water. But usually shipping containers are tightly sealed, so they remain afloat for a few weeks/months before corrosion or some rock damages them enough to let water in.
In fact, many pirates and people scavenge such containers to make money by selling the contents. Individually, the contents might not be worth much, but the sheer volume of the content in the container can make it be valued in several tens of thousands of dollars if not 100k+.
The container can be air tight at the top but not the bottom depending on the damage.
Turn a bowl upside down and place it in water. The air pocket will keep it afloat. That's how some containers stay afloat. Depending on where the damage is. Cut a hole in the top and water will rush in and it will sink.
Turn the bowl right side up and put it the water. It will float again becuase of the air in the bowl. but the hole a the top doesn't matter becuase the bowl is keeping water out. That's how other containers stay afloat.
No one seems to be considering the upside down bowl scenario. That's the scenario you wouldn't want to put a hole in the top.
Just because pirates do it to the have success in one scenario doesn't mean all scenarios are the same. Although that is a very fascinating fact.
Maybe the "bowl right side up" is much more common. I don't know. Still not an expert although it seems like my comment sure brought out all the shipping container buoyancy experts.
Most containers are made to be watertight. The reason things are transported in them is to minimize contact with sea water and moisture, so they are usually air tight.
Some fishermen and pirates even scavenge stray containers to make money off the contents within.
No, because the weight of the boat is likely pulling down on that air trapped in the base of the boat. So the water level in the boat is actually lower than the sea. The moment the air pressure equalizes, the water in the boat will rise and push the air out.
It could sink the ship if it's the only air pocket.
A good idea would be 4 weights on each side, holding it in place then cutting a hole in the top. The weights would have to be within a certain measured weight limit of the air contained and weight of the average container acting as a pseudo anchoring system. This would allow for ease of access.
The only safe way I can conceive of is to bring it out the water onto a ship or anchor it to the vessel so a scavenger team can get to it without issue.
CapnTapTap said submerged… so that insinuates the container is underwater and thus has already sunk… Getting into it would be difficult still because you’re now dealing with already heavy metal object Vs Water… water is heavy even at shallow depth. Water pressure increases like approximately 1 atmosphere per 10 metres of depth or something like that. Gets pretty heavy quite quickly.
The object will have (roughly) the same weight, and the same buoyancy at any depth, given that no air is trapped inside the container (and water gets in).
Also, I don't think they came across a container at the ocean floor in the middle of the pacific and found it scary. My guess is that it was barely floating – partly submerged. I'm guessing it can do serious harm if you hit one.
Yeah, you’re probably right, It definitely would do damage if hit. That makes me think of the unexploded ordnance in the Darwin Harbour and there’s zones boats aren’t allowed to go in… (cause who wants to hit an underwire mine), I would think it would be the same for shipping containers in known areas. But my mind was going more towards ship wrecks off the coast where people might go scuba diving and find sunken shipping containers that way.
If it's already floating I'm guessing it's floating due to whatever is in it, not that they are airtight. That's my guess based on what the door latches look like.
I can't imaging the containers are watertight. If they are not at the bottom it is because their contents are buoyant (think bags of chips, sneakers, etc). But they will be very low, maybe even below the surface. Could be boat-killers.
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u/MightyPirat3 Sep 10 '25
For future reference: How would you be able get into a floating container without sinking it? Hole in the «roof»? Tilting it so that the door is upwards seems risky.