VPM References

The Varying Permeability Model - VPM was originally developed by Prof. David E. Yount from the University of Hawaii. Over a period of several years various people contributed to the development of the algorithm. Most notably Erik C. Baker and Eric Maiken from the “decompression list” developed various FREE programs and extended the model.

Understanding the VPM is not something that will happen overnight, but hopefully this section will provide a "step by step" recipe that will help anyone trying to extend his/her knowledge about the model. It's definitely worthwhile to do so.

Basic Decompression

Before delving into the VPM, it's obligatory that one fully understands haldanean models. For this purpose the following sources are worth mentioning:

• "Understanding M-Values" by Erik Baker
• "Introductory Deco Lessons" by Erik Baker
• "DIY Decompression" by Stuart Morrison.
• www.deepocean.net (tech section) Jörgen van der Velde's web site (start with the basic decompression section) 

VPM Basics

The following two documents are a good start to VPM decompression model:

• "Bubble Decompression Strategies" by Eric Maiken Small remark: on all illustrations and formulas in this document skin pressure (Pskin) points in wrong direction.
• "VPM - The Inner Workings" by Marcin Kaluza A thorough explanation of the model intended for divers rather than scientists with a lot of practicalities thrown in as a bonus. This document is also available in French and Polish.

Advanced VPM

Documents in this section provide value only for really inquisitive types as they are loaded with heavy math and physics and are of very little practical application. If however you would like to know how the model has been derived they are indispensable:

• www.deepocean.net (tech section) Jörgen van der Velde's web site: look for "bubble deco models".
• Derivation with Explanation of the VPM Dynamic Critical Volume Algorithm of Yount & Hoffman (1986) by Erik Baker
• Implications of the Varying Permeability Model for Reverse Dive Profiles by D.E. Yount, E.C. Maiken & E.B. Baker. This document is really worth a read as it provides general insight into the VPM as well.

Printed material

The following books provide not only VPM explanations but are well worth the read for anyone interested in diving physics:

• "Hyperbaric Medicine and Physiology" (Best Publishing Company, 1988) where prof Yount published "Theoretical Considerations of Safe Decompression" which is  probably one of the best texts on the model.
• "Technical Diving in Depth" by Bruce Wienke. According to the preface "not intended for pedestrians". :)
• "Basic Decompression Theory and Application" by Bruce Wienke