- 33.03 feet sea water = 1 Atmosphere pressure = 14.7 psi
- 34.03 feet fresh water = 1 Atmosphere pressure = 14.7 psi
- PV=nRT
- P=T/V or V=T/P or T=PV
- P = pressure in psi
- V = volume in ft
^{3} - n = moles of gas (1 mole = 6.022 x 10
^{23}atoms) - R = gas constant 10.7316 psi ft
^{3}/ lbmol °R - T = temperature in Rankine (°R) = °F + 459.6

- P
_{guage}= 14.7psi x [depth of sea water] / 33.03 feet sea water - P
_{absolute}= 14.7 + (14.7psi x [depth of sea water] / 33.03 feet sea water) - Sea water weighs 64.58 lbs/ft
^{3}pr 8.6213 lbs/gallon Specific gravity = 1.035 - Fresh water weighs 62.4 lbs/ft
^{3}or 8.3303 lbs/gallon Specific gravity = 1.000 - Bouyant Force (Archemedes Principle): F
_{buoyant}= W_{in air}- W_{in water}= dgv- F
_{buoyant}is the buoyant force - W
_{in air}also known as dry weight - W
_{in water}is weight in water [remember that negative numbers are positively buoyant] - d is the density of the liquid [salt water is 64.58 lbs/ft
^{3}and fresh water is 62.4 lbs/ft^{3}] - g is the gravitational acceleration 32.37 ft/sec
^{2}(normally written as 1 in the equation i.e. 1 gravity) - v is the volume of the object in cubic feet (ft
^{3})

- F
- For calculating the tissue depth for Haldanean decompression M-values, an easy to remember formula is: D
_{final}=[1-2^{-(t/h)}]*D_{actual} - D
_{final}= the final tissue depth - D
_{actual}= actual dive depth - t = time underwater
- h = 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: http://quashnick.net/scuba/university/Nitrox_for_R.txt
- A better option is to use the R-Project (http://r-project.org) Package called scuba. You can find it here: http://cran.r-project.org/src/contrib/Descriptions/scuba.html

http://physics.itsbaxter.com/links.html - Good site for more information on the physics of scuba diving.

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