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Diving 107: Scuba Diving Underwater Physics

The original page can be found here:

33.03 feet sea water = 1 Atmosphere pressure = 14.7 psi
34.03 feet fresh water = 1 Atmosphere pressure = 14.7 psi

or or
= pressure in psi
= volume in ft3
= moles of gas (1 mole = 6.022 x 1023 atoms)
= gas constant 10.7316 psi ft3 / lbmol °R
= temperature in Rankine (°R) = °F + 459.6

Sea water weighs 64.58 lbs/ft3 or 8.6213 lbs/gallon Specific gravity = 1.035
Fresh water weighs 62.4 lbs/ft3 or 8.3303 lbs/gallon Specific gravity = 1.000

Bouyant Force (Archemedes Principle):

is the buoyant force
also known as dry weight
is weight in water [remember that negative numbers are positively buoyant]
is the density of the liquid [salt water is 64.58 lbs/ft3 and fresh water is 62.4 lbs/ft3]
is the gravitational acceleration 32.37 ft/sec2 (normally written as 1 in the equation i.e. 1 gravity)
is the volume of the object in cubic feet (ft3)

For calculating the tissue depth for Haldanean decompression M-values, an easy to remember formula is:

= the final tissue depth
= actual dive depth
= time underwater
= halftime compartment

I have written a function for the R language which calculates the EAD, PO2 and working depth for any FO2 breathing gas blend.
You can find my simple function here:
A better option is to use the R-Project ( Package called scuba. You can find it here:
Links - Good site for more information on the physics of scuba diving.

Posted at 12/13/07 on 2007/12/13 by Stephen - Category: Scuba University -
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