What's typical buoyancy in just swim wear with no equipment?

[crunchiespg]

I was playing around in the pool with my daughter today and having now got an appreciation to buoyancy from my diving I was figuring out my buoyancy in just swim shorts. I was also practicing the float skills for the divemaster course (along with trying to improve my 400m swim time)
But this got me thinking. What is typical for buoyancy?
I found I float like a bobbing cork with my chest rising out of the water with a full breath. And about half way through exhaling I start to noticeably sink and towards empty lungs I sink like a stone. I can exhale and sit solid on the bottom of the pool. Hitting it with quite a thump if I wish.
My legs are also noticeably more negative than my torso. Which is good as all my diving is in a dry suit and that makes them feel pretty buoyant so I'd hate it if my legs weren't so negative.

So what is typical?

 

[Lakediving]

My legs feel negative too.

 

[crunchiespg]

My legs feel negative too.

What about the rest? I was surprised how much of a change I have between being very very positive with full lungs to very negative empty. I thought most people were a bit positive even with empty (ish) lungs.
I have a pretty big chest so I guess that explains it a bit.

 

[tbone1004]

legs are usually heavy, no fat, lots of muscle, no lungs. Your chest will almost always float due to your lungs.

No such thing as typical buoyancy for people, it all depends on your personal body makeup whether you sink or float. I sink, most people float, my brother sinks more than I do....

 

[crunchiespg]

legs are usually heavy, no fat, lots of muscle, no lungs. Your chest will almost always float due to your lungs.

No such thing as typical buoyancy for people, it all depends on your personal body makeup whether you sink or float. I sink, most people float, my brother sinks more than I do....

Can you make yourself float with a full breath? That's what I found so surprising with me. I went from a very buoyant floater to a very negative sinker depending on breath. I expected to be more skewed to one or the other. Not both.

 

[Bob DBF]

Neutral, plus or minus, depending on the amount of bioprene. Legs tend to be negative due to the muscle which is negatively buoyant. The more fat you have the more buoyant you will be.


Bob

 

[cwoco]

I'm very barely positive when at absolute MAX inhale, very negative when exhaled. I can only float on my back when my lungs are filled to bursting - that means breathing, even in tiny breaths, is pretty much impossible. In sea water I can float on my back with tiny breaths, but then feel too low on oxygen to do that for more than a minute or two.

I can sink like a stone if I exhale ~30-40% of my lung capacity (i.e. to normal, resting average capacity). When my girlfriend and I were learning to use our newly ordered SMB's in her pool (with no tanks), I could partially exhale, sink to the bottom of the pool and still have enough breath to orally inflate my SMB.

My sister is about as negative as me, so we reckon it's a genes thing.
I use that as my excuse for my weak swimming - too much energy spent keeping afloat, too little left to move forward.

 

[tbone1004]

Can you make yourself float with a full breath? That's what I found so surprising with me. I went from a very buoyant floater to a very negative sinker depending on breath. I expected to be more skewed to one or the other. Not both.

yes but barely. only because I have a very large lung volume from being a big guy as well as a singer/tuba player, so my lung volume is very large. On a "normal" breath I still sink. My comment regarding chest floating was that if you hang at the surface you will usually stay with your shoulders right at the surface and your legs down, this is part of why many people have "heavy feet" problems on scuba, you have more neoprene, less muscle, and your lungs all trying to make your chest area float while your feet are trying to sink.

 

[ronscuba]

I am negative when breathing normal. I float if I hold a full breath.

 

[Texasguy]

I think the idea, when you float, is to have full lungs, when you exhale, you only remove like 20-25% of the air, leaving the rest. Shallow breathing on full lungs, of sorts. This way it keeps you buoyant and there is exchange of gasses.