VPM — What It Is and Why It Matters
VPM (Varying Permeability Model) is a bubble-based decompression algorithm that focuses on the physics of gas bubble nucleation and growth. Developed by David Yount and refined by Erik Baker (as VPM-B), it models how micro-bubbles in tissues respond to pressure changes and calculates ascent profiles designed to keep bubble growth within safe limits.
VPM-B tends to prescribe deeper initial stops followed by shorter shallow stops compared to Bühlmann with standard gradient factors. It is available on Shearwater dive computers as an alternative to Bühlmann ZHL-16C and is favored by some technical divers for its bubble-mechanics approach.
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Frequently Asked Questions
Is VPM better than Bühlmann for technical diving?
Both are widely used in technical diving. VPM-B prescribes deeper stops, which some divers prefer for deep decompression dives. Bühlmann with gradient factors is more customizable and has a larger base of empirical data. Neither is objectively better — it comes down to diver preference and experience.
Which dive computers support VPM?
Shearwater dive computers (Perdix, Teric, Peregrine) offer VPM-B as an optional algorithm alongside Bühlmann ZHL-16C. Some open-source dive computers and desktop planning software also support VPM-B.
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