Loss of human body volume vs depth (buoyancy)

[Divin'Papaw]

i understand the reasoning some people use. i certainly do not want to open up that can of worms, especially in this forum. i just think the ease of having some ditchable lead far outweighs any down side. just my opinion.

Then by all means you should carry some ditchable weight. Dive the way you’re comfortable.

 

[loosenit2]

Id like to do a test where I am not wearing exposure protection, am negatively buoyant, empty wing and I measure how negative I am with a fish scale just under the surface, go down to 100 feet amd measure again. The difference in gas will be negligible.

I refuse to do this in local waters however.

this would be a fascinating experiment.

 

[wetb4igetinthewater]

this would be a fascinating experiment.

Maybe I should start a GoFundMe to send me to Guam?

Come on people! It is for science!

 

[lowwall]

this would be a fascinating experiment.

Why? We already know the outcome. Your tissues and fluids won't compress and your air spaces will be inflated by air at ambient pressure, just as they are at the surface.

Freedivers (and other air breathing marine animals) will compress at a rate determined by the depth and the volume of the air spaces in their bodies at the surface.

 

[James79]

If one establishes that say it is possible to swim up from say (arbitrarily) 15m depth with a fully deflated bcd with the weighing being carried, what does that actually mean from a max depth you could swim up from perspective?


The question arises with respect to having non-ditchable weights on a scuba system without redundant buoyancy ie wetsuit + bcd, rather than drysuit + bcd (not considering a dSMB as extra redundant buoyancy, although that is one possible option clearly)

Have you played with this: Optimal Buoyancy Computer ?
Rsingler (and his fellow contributors) has formulas in it to account for wetsuit compression at varying depths. I've used it reliably to nail down changes needed with changing gear, and have found it to be pretty darn accurate (within the ranges of my diving).

Respectfully,

James

 

[wetb4igetinthewater]

Why? We already know the outcome. Your tissues and fluids won't compress and your air spaces will be inflated by air at ambient pressure, just as they are at the surface.

Freedivers (and other air breathing marine animals) will compress at a rate determined by the depth and the volume of the air spaces in their bodies at the surface.

Stop messing with my GoFundMe for Guam!!!!!!!

 

[inquis]

having some ditchable lead far outweighs any down side.

Define "some".

Dropping 5 lbs if you lose your wing at the beginning of a dive on a single AL80 will make you neutral at whatever depth you targeted when selecting that weight. Hopefully that 5 lbs is enough to get you "over the hump" as far as wetsuit expansion and get off the bottom. Then it's easy to hold a safety stop when neutral at that depth.

Drop 20 lbs, and you will find it very difficult to make a controlled ascent. Your call if you're OK with the resulting rate as your wetsuit regains buoyancy.

So yeah, it depends on how much you're short, which depends on a lot of things.

 

[loosenit2]

Why? We already know the outcome. Your tissues and fluids won't compress and your air spaces will be inflated by air at ambient pressure, just as they are at the surface.

Freedivers (and other air breathing marine animals) will compress at a rate determined by the depth and the volume of the air spaces in their bodies at the surface.

because a bunch of folks posting on SB that they know the answer does not convince me that the question has been answered in a rigorous manner, a lot of common knowledge is simply wrong. I would prefer to see a published paper or research experiment document the outcome. I did a quick search on google and google academic and could find no paper indicating research had been done on the volume of the human body in other than 1 ATA of pressure and note that no-one in any of the responses linked such a paper; although I have to believe that NASA has done such an experiment. More than the answer I think the design of the experiment, either under water or using a hyperbaric chamber would be interesting.

 

[wetb4igetinthewater]

because a bunch of folks posting on SB that they know the answer does not convince me that the question has been answered in a rigorous manner, a lot of common knowledge is simply wrong. I would prefer to see a published paper or research experiment document the outcome. I did a quick search on google and google academic and could find no paper indicating research had been done on the volume of the human body in other than 1 ATA of pressure and note that no-one in any of the responses linked such a paper; although I have to believe that NASA has done such an experiment. More than the answer I think the design of the experiment, either under water or using a hyperbaric chamber would be interesting.

And more importantly, I have not yet been to Guam!

 

[ofg-1]

Just get in contact with Len Whitlock, he did 2000 plus feet in a chamber, I don't think he shrunk much.