eli5: Why do we sink when drowning and float when we die?
In: Biology
Floating is caused by decomposition, which is a natural process that releases gases (bacteria in guts) as the body breaks down. So the body floats.
You always float, dead or alive. If you’re drowning, it is because there’s an undercurrent, or you are panicking, or the water is extremely choppy, or there are undercurrents dragging you down etc..
There’s something called a dead man’s float … ngl, it isn’t an encouraging term, but it basically suggests you allow your head to be submerged (you’ll float), and then just stick your head up every 15 seconds or so as you need to breathe.
So the issue isn’t really floating… you’ll float when alive… the issue is periodically getting your mouth into the air to breathe.
Then, if you fail to breathe, as u/fyrezard points out, the natural process of gas release from bacteria in your guts after death will ensure you float.
tl;dr
you’re mostly going to be floating. Don’t worry about that. It is the breathing you need to focus on.
Humans are only just barely buoyant in water. Most drownings happen right at the surface ironically enough unless there is a current or other factors at play, but while the body as a whole is right near the surface, the head can still have a hard time sticking out of the water enough to get a clean breath in, especially if you are panicking and flailing which disturbs the water and makes it harder to float.
After a while dead bodies can bloat with gas as they decay which pushes them up to the surface, but there are numerous recorded cases of dead bodies sinking or staying sunken until disturbed, often in cold deep lakes.
Sinking while drowning is mostly due to panic, anybody can float if they fill their lungs with air and lay on their back regardless of if they can swim or not. Obviously there is to it than that depending on situation (choppy waters, currents etc) but panic and shock are the main killers when it comes to drowning
Well it depends how much fat you have, what you are wearing, and whether you have air in your diaphragm. If I hold my breath in, I float. But if I breathe it all out, I sink. So if breathed out my air and didn’t know how to swim, I would be sinking and thus not able to refill with air to gain more buoyancy. But my wife (not fat, but a woman and so proportionally more fat than I am) can float with or without holding in a breath.
As other’s have said, when you are dead, other gasses can cause buoyancy.
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