Ratio Deco

This class is not sold directly online.  If you'd like to sign up or have questions:


The Ratio Deco class is designed to study, discuss, analyze and understand a wide variety of existing decompression models and their pros and cons.  During the class you will develop a strategy wherein you apply the best of each of these theories to your personal diving application.  Ratio Deco is a methodology that allows a diver to apply various existing decompression models into a cohesive strategy that the team can apply during a dive.  It is decompression “on the fly.”  Ratio Deco is not a scientific decompression model or theory, but rather it is an application of those theories.

Using ratio deco requires a series of requisite parameters including, but not limited to, complete situational awareness, cohesive team diving, standardized UTD gases and deco mixtures, and a thorough understanding of the ratio deco methodology and all its parameters, along with the discipline to stay within those limitations.  The user of Ratio Deco must acknowledge the need to build real-life, in-water experience with study, practice and an awareness of risk versus benefits.

This class covers in detail all the aspects of ratio deco, or what is better known as "decompression on the fly."  We start with the history of decompression modeling, Henry's law, Haldanean theory, US Navy, Workman, Bulhmann, VPM and RGBM, and most importantly how we apply these to our personal decompression strategy.  You will also understand the overall concept of a safe and repeatable ascent strategy and how to essentially do "deco on the fly."  The class will end with examples and exercises.  This is an academic-only class normally conducted over one 8-hour day.

Class Information

This is an academic-only class conducted over 8 classroom hours.  There are no dives required for this class.  The class covers current and past decompression models, including the history of decompression.  Coverage includes gas laws, the physics and history of dissolved gas decompression models, the physics and history of bubble theory models, "min deco" profiles for no-decompression diving, ratio deco profiles for decompression diving, decompression curves, “on the fly” decompression planning, standard gas mixes, the benefits and dangers of oxygen, nitrogen, helium, and carbon dioxide, and planning your personal decompression strategy.


  • Minimum age of 18
  • Must complete UTD online registration process
  • No smoking