Amounts of pressure within 33 ft?

[spoolin01]

It's only the water directly on top of you that affects you.

That part needs reworking (see knowone's post).

If you sized the tube to just fit over your ears and sit on your shoulders, what would happen? (it would happen to me too, even though considerable water would leak past my big ears)

 

[DevonDiver]

If this was true....then the depth of water below a diver...and the distance of water laterally surrounding a diver would have an impact (variables) on the pressure. However, those issues are constants when calculating pressure at depth.

As we know...every action has an equal and opposite reaction. Thus, the water below the diver (and the seafloor) does 'push up', only so much as it allows the pressure to exist. It does not actually 'contribute' to the pressure.

 

[RJP]

Anyone want to rehash this?

No.

:cool2:

 

[dmoore19]

The hydrostatic pressure of seawater can be calculated by:

WW= weight of water in Pounds Per Gallon
.052= constant factor

Sea water weighs +/- 8.552. This varies with where you are and temperature but it is a good average.

WW X 0.052= psi per foot

8.552 X 0.052=.444704 psi/ft

.444704 X 33= 14.67 psi at 33'


so you could say that .444704 X depth = psi/ft

psi/ft/14.7=ATM (atmosphere of pressure)

because it is expressed in PSI (pounds per square inch) you could have a column that is 200' in diameter or one that is 2' in diameter and the psi is the same.

You could do the same thing for fresh water:
Fresh water weight 8.33 ppg

8.33 X 0.052=.43316

so the pressure of freshwater is .43316 psi/Ft

so the psi at 33' fresh water would be 14.29' or .97 ATM


Hope that helps.

 

[dmcutter]

It's the old "for every action there is an equal and opposite reaction" thing. If you are in 33 ft of water and neutral, and let's assume horizontal so the pressure is equal over your whole area is equal, the column of water over you is exerting 2 atm worth of pressure on you. The water under you is exerting the same 2 atm of pressure, otherwise you would be sinking. The horizontal extent of the water doesn't matter. When you look at hydrostatic pressure against a structure (or even just lateral earth pressure) it is a function of depth and density of the medium. A column of water 1 inch thick and 10 ft deep exerts the same hydrostatic pressure on a basement wall as a 1 ft or 5 ft thick. Strange but true...

 

[Doubler]

To make it easy for every 1 Ft of decent pressure increases .442

 

[dumpsterDiver]

to make it easier, pressure increases about 0.5 psi for every foot of descent.... close enough for governement work....

 

[dmoore19]

All depends on the density of the water.

 

[RJP]

All depends on the density of the water.

Or how dense the diver is!

 

[dumpsterDiver]

Or how dense the diver is!

Do big fat divers expereince more pressure because they have more surface area? Also, if you lay flat, do you feel more pressure since their is more water above you than if you stand in a vertical position? Is that why PADI wants their students to kneel...so that they get less pressure and absorb less nitrogen?