The swimming thread in IMHO got me to thinking about this.
Some people who can’t swim say that they sink like a rock. Is this possible? Aren’t we all built more or less the same? Or is there some magic body fat percentage that makes one wholly unboyant?
I sometims suspect that some people feel themselves start to sink a little (which is normal), then panic and give up forever. But I could be totally wrong about that.
Body fat helps buoyancy, because more water is retained in the body.
Higher body fat % = more buoyancy; hence the body-fat calculation method that sees people dipped into large tanks of water to determine their body fat %.
helpful…
“Why don’t we float alike” article:
I can tell you I DONT float well. Fully inhaled and held breath, totally motionless, in fresh water I am lucky if I dont sink. Salt water, just the very top of my head is above water.
I have to tread water to actually breath. I also can’t sorta float on my back like some. My lower half is defininetly not bouyant and without fighting it, my body assumes a vertical, not horizontal position.
Do you put your head back? The thing is, if you lift your head, your lower body will sink. And if you’re a little panicky about sinking, your natural reaction would be to raise your head.
One thing I’ve found is that floating is largely an act of faith.
If I try to lay back, I can float on my back, but my legs dip. But, I can breathe, and possibly survive out in open water (or so my logic tells me).
If I try to tread water, no amount of flailing will cause me to float, and I’ll probably exhaust myself in a minute. At best, the water is at mouth level. If I do nothing and try to remain buoyant (like sitting back in a seat), the water level is at least 4 inches above me.
I can also sit at the bottom of a diving well, no problem, as well as lay down there in a prone position and act as if I were dead.
I recall that in bootcamp, when we had to step off the one meter platform whether we could swim or not, one fella did indeed sink to the bottom. While most people will at least float to the top, this guy just sat on the bottom, waiting to be rescued. Weirdest thing I ever saw.
Witches!
Personally I have never managed this act of witchcraft myself. With a lungful of air and relaxing I normally end up on the bottom of the pool. Maybe it’d work in salt water.
I am not all panicky about water or sinking. I used to love exhaling and sitting of the bottom of the pool because I could do it so well. If I exhale, I definitley sink like a stone.
Under extremely favorable (laboratory) conditions, I might be able to keep a nostril barely above water without treading. If I am inhaling and exhaling (unless I exhale REAL fast, then inhale and hold it) my average bouyance is darn close to zero, if not negative.
I used to practice all that stuff they tell you to do survive long periods in/on the water. None of the low energy stuff even came close to working for me.
Open water? I gotta tread some to breath.
Thats why no mater how warm the water is, I always wear a wetsuit scuba diving. I want some guaranteed positive bouyance that will keep my head easily above water should something bad happen and I end up alone in the ocean for awhile.
When I was getting my open water certification, I regularly had to use every leftover weight on the boat. I’m not a freaky monster fat-wise, but my height paired with my fat makes a lot of fat overall compared even to small, normal people that have a higher BFI. All the same, it’s embarrassing using all of the leftover weights.
I mean to take up freshwater diving next, and have no plans to try the Great Salt Lake or the Dead Sea.
Anyone will sink if they exhale. I float and I have almost no body fat at all.
I can’t swin and I sink like a rock. I am pretty sure it is because I’m so tense in the water. Dead people float (well mostly) but even if I am in the bathtub, I can relax my arm and have it float but as soon as I notice it, it sinks.
I think a fear of water or stress effects you without you noticing it. I know thin people who float and fat people that sink, at least in my case and the people I’ve known we’ve had some kind of water fears or issues.
Oh, I forgot to add, the OP noted that people who “can"t swim” claim to sink like a rock.
I consider myself a decent swimmer, been doing it since I could walk. I canoe, I sail, I scuba, I’ve even cave dived a few times. I have no inate fear of water.
So, at least in my case, my poor floating abilities have nothing to do with some mental projections of a fear of water or lack of swimming skills.
At one time I could not swim a stroke. I got cheesed off just sitting by the pool when on hols so I took swimming lessons.
I was totally useless, flailing about, arms and legs all going in different directions and eventually I sank like a stone.
Now after umpteen lessons I can swim, not a lot and not very well, but at least I can now join in the frolics in the pool and get to ogle the ladies up close 
I can swim if my life depends on it, but it looks like I’m swimming as if my life depends on it.
Repeated efforts at floating have done nothing. I’m in billfish678’s situation. I go vertical and slide into the water like the Titanic.
Please ignore my broad brush.
I wouldn’t have believed it if I hadn’t seen it decades ago, but former heavyweight champ Joe Frazier sank like a stone in the pool during the swim race in an episode of “The Superstars.” Many observers really thought he was going to drown. Eventually, he managed a weak dog paddle and completed the race about 20 minutes after everyone else.
He admitted later he didn’t know how to swim, but thought he’d give the swimming race a try anyway.
Totally dependent on body fat.
I’m borderline.
When I am in my swimming pool, if I exhale, I will slowly drop to the bottom. I can then sit happily there, freaking folks out, until I feel the desire to breathe.
If I have a lungful of air, my head stays above the surface.
I imagine some totally ripped dude would drop like a stone due to a low BMI.
Being able to swim has little to do with body fat: look at Olympic swimmers, or even your garden variety triathlete.
Being able to float correlates to body fat, but also muscle tissue. I took a lifesaving class as a student at a large, state school. One guy in the class wrestled. He was in great shape and had as little body fat as anyone. Another student was a girl in good enough shape to swim and pass the class, but more overweight than anyone else in the class. The instructor actually used the two of them as demos. The wrestler maintained perfect floating form to the bottom of the diving pool, while the girl didn’t seem to break the water’s surface tension.
My dad served in the navy, and swims well. He can take a full breath and sink to the bottom of the deep end of the pool (10 - 11 feet). At least, he used to be able to…he is 70 and hasn’t been in a pool in a while. He’s 5’3" and weighed in at 160 - 170lbs. He was strong, but nothing about him said “bodybuilder” and he had quite the gut. The gut did not float.
The last time I was in water I was borderline. I’d float so long as I had a reasonable amount of air in me. If I exhaled and didn’t breathe in again before I went under I’d soon be at the bottom.
I’ve put on a little padding so I might be a bit better off now.