VPM Technical Publications 



Materials Copyright 1999-2009 by Eric Maiken, Erik Baker, and David Yount




Here are links to articles and publications on the VPM and decompression modeling

Decompression.org ftp site

Folders full of decompression-related technical articles and computer code are at the site:


To access the site, you'll need login credentials (anonymous ftp will not work):

  • username: downloadfiles@decompression.org

  • password: decompression1
  • My folder is:


    VPM-B Decompressions Compared to RGBM, GF-Buhlmann, and NOAA Tables

    Back in 2003-2004, I ran hundreds of ascent profiles through a number of commercial programs, and quantitatively compared VPM-B decompressions to ascents calculated by RGBM, GF and NOAA algorithms.

    For a wide range of depths and gas mixtures, the commercial programs V-Planner (running VPM-B) and GAP  (Running RGBM) produced VPM and RGBM -based ascent tables with stop times and compartment-gradients that were highly correlated. For many dives, the decompression schedules calculated by the two methods were virtually identical. On the other hand, Buhlmann-GF tables generally required much longer decompressions for long bottom times, compared to either VPM or RGBM. So, VPM and RGBM tables were generally much more similar to one another than either was to GF-Buhlmann tables.

    There are a few notation and formatting errors in the docs:

  • The notations for gas mixtures are mixed-up. For example, Nitrox mixtures were referred to as 50%, Nitrox 50/50, and even 50/50 (which should imply 50% Helium and 50% Oxygen to most divers).
  • Many graphs have broken-fonts in their labeling. In particular, dots "." show-up where parenthesis () or brackets { } should have been. This obscures the details of some of the gas mixtures, which should have been labeled as {%O2,%He,%N2}

    Here are 8 pdfs that compare decompressions by VPM to ascents on other models:

    0.  Read First

    1.  200 ft (61m) on Trimix 18/54: VPM-B vs RGBM and GF-Buhlmann Ascents

    2.  200 ft (61m) on Trimix 18/54: HSE-RGBM vs. GAP-RGBM Ascents

    3.  200 ft (61m) on Trimix 18/54: Tensions and Gradients

    4.  100 ft (30.5m) on Air: VPM-B vs RGBM and GF-Buhlmann Ascents

    5.  100 ft (30.5m) on 32%: VPM-B vs RGBM and GF-Buhlmann Ascents

    6.  100 ft (30.5m) on Trimix 30/30: VPM-B vs RGBM and GF-Buhlmann Ascents

    7.   300 ft (91m) on Trimix 10/70: VPM-B vs RGBM and GF-Buhlmann Ascents


    UHMS Meeting
    Stockholm, Sweden, June, 2000

    During 1999 and 2000, David Yount, Erik Baker and I collaborated to extend the VPM decompression algorithm to model repetitive, mixed-gas decompression diving. The following material includes publications as well as behind-the-scenes discussions of technical aspects of the VPM as applied to the real world of diving.

    David Yount passed away just prior to this presentation of the details of the latest development of his VPM diving decompression algorithm. Mahalo David! How fortunate you were to see your pioneering work in decompression theory come to fruition.

    A poster, in powerpoint format, describes A New VPM Algorithm for Repetitive Dives , David E. Yount, Eric B. Maiken, and Erik C. Baker

    The Reverse Diving Profiles Workshop
    Washington D.C., USA, November, 1999

    Our manuscript Implications of the Varying Permeability Model for Reverse Dive Profiles , David E. Yount, Eric B. Maiken, and Erik C. Baker is available in pdf format. 

    "VPMechanics" Series of Mathematica Notebooks

    The following pages were created from Mathematica notebooks that I put together during discussions with David and Erik as we prepared for the Reverse Diving Profiles Workshop (RDPW). The pages need some work to fix broken fonts that were created by saving the original Mathematica notebooks in html.

    RDPW3A.htm Tracks the compartment tensions and supersaturation gradients of a reverse dive profile posted by Erik Baker on the deco mailing list. 9/13/99

    VPMechanics1.htm Discusses the VPM algorithm, with application to a 100 fsw air dive. 9/14/99

    VPMechanics2.htm Looks at the time dependence of the supersaturation gradient for the air dive in VPM1 and evaluates the integral of Pss as a risk function. 9/15/99

    VPMechanics3.htm Considers the roles of actual dive depth and equivalent air depth in setting ascent schedules in air and nitrox diving. 10/22/99

    VPMMechanics4.htm Evaluates VPM supersaturation gradients throughout the permeable and impermeable regimes. 9/23/99 

    VPMechanics5.htm Joins the hypobaric and hyperbaric forms of the VPM M-values. 9/26/99 

    VPMechanics6.htm Looks at how the VPM parameters and dive conditions affect the allowed supersaturation gradients. 10/4/99

    VPMechanics7.htm How a diver's descent rate influences the minimum ascent gradients.  10/23/99

    VPMechanics8.htm How a diver's ascent rate affects the minimum ascent gradients. 10/14/99

    VPMechanics9.htm A close look at the dynamic critical volume method for non-decompression diving. 11/1/99

    VPMechanics10.htm Repetitive diving and the VPM. 11/1/99

    Some Notes on the VPM Model

    Technical VPM