Are arms positively buoyant?

[TMHeimer]

Bare arms and legs are negative. They are muscle and bone, so there's no way for them to float. If you add neoprene, it adds some buoyancy depending on the thickness.

In fresh water I presume. In salt water I can float on my back without my legs sinking (or obviously I would be vertical). I guess the specific gravity of 1.03 salt vs. 1.0 fresh accounts for that.

 

[Bob DBF]

The first is why some people swim with arms extended more or less "Superman-style."

I use it a lot when there is heavy surge in low viz, I can deflect myself off obstacles faster than with my arms in the @happy-diver position, which I maintain when my arms are not in use. I also use it when underwater cliff diving, which I've found to be much safer than the real thing.


Bob

 

[foob]

My arms are definitely not buoyant. I dive like a zombie

 

[Lorenzoid]

The only part of a human that is positively buoyant are the parts with air. Your arms are bone wrapped in a meat sandwich. Your legs are also bones in a meat sandwich. Your lungs fill with air and provide buoyancy. If you wrap them in floaty stuff they can float. . . .

Agree with that characterization. Our body tissues are mostly watery. By hedging my "neutral" with "relatively," I was alluding to the composition of flesh, bone, etc., as not having exactly the same density as the water, and that can vary slightly among individuals depending on body composition--amount of fat, bone density, etc. Other than the lungs, I think it is reasonable for diving purposes to characterize our body parts as "relatively neutral."

 

[Steve_C]

You, your equipment, and any air pockets have a center of mass. Extending or retracting arms or legs can effect the center of mass and also affect moment of inertia. Human body parts all by themselves are a bit negative in fresh water.

 

[BlueTrin]

I just learned that fat is positively buoyant

900g per litre

Probably not enough to offset the rest of the body without the lungs and other air cavities though ...

How Much Does 1 Liter of Fat Weigh?

 

[Lorenzoid]

I just learned that fat is positively buoyant

900g per litre

Probably not enough to offset the rest of the body without the lungs and other air cavities though ...

How Much Does 1 Liter of Fat Weigh?

They don't call it "bioprene" for nuthin'!