VR Technology Limited
VGM - Decompression philosophy
The VGM algorithm has been built on recent practical dive planning and diving
techniques as well as the scientific and theoretical understanding over the past 100
years. It combines a better theoretical understanding of bubble physics together with
known diving practices that help decompression and well being during and after
decompression diving.
VGM also gives the user the ability to change the conservatism of the decompression
to make it not only more conservative, but also more aggressive. Some technical
divers find they feel good after a decompression with less in water time than others.
The equivalent gradient factor for the VGM setting is displayed for comparison with
other dive planning software and computers.
The default settings will suit many experienced divers, and it is the input of real
technical divers in the choice of these settings that has made VR Technology and its
team at the forefront of technical diving product design for over 20 years.
Decompression is a physiologically complicated event. There are many factors that
affect how well the human body decompresses and how well it is able to withstand
pressure exposures. All dive algorithms have been devised to combine the complexity
and risk of staying in the water with the risk of decompression sickness after
surfacing. Things like hydration before a dive, and rest and hydration and even
oxygen after a dive all help reduce the risk of DCS. So bear in mind that as with all
decompression planning there needs to be a balance and understanding of the risk
of reducing decompression times and the impact of DCS. Please refer to your training
agencies’ information and advice on these issues.
VGM incorporates 5 main features:
1. Haldane decompression model, based on Buhlmann ceofficients
2. Modification of tissue over pressure tolerances or M values for the faster
tissues to create a decompression profile similar to a bubble model like VPM
3. Further modification of over pressure tolerances for deep or long exposure
dives, especially in the fast and middle order tissues
4. Automatic adjustment of the above parameters to allow the default settings to
give common decompression and No Stop times across the range of diving
from 10m to 120m
5. User adjustable parameters so the diver can use his/her experience to further
modify the decompression to that which suits him/her. The equivalent gradient
factors are displayed for a particular dive for ease of comparison with other
dive computers and dive tables, although because this system goes beyond
gradient factors certain adjustments may only give an estimate of the nearest
GF equivalent.
A basic version of PC dive planning software (VGM ProPlanner) is available free
from the web site. This allows a quick way to see what decompression the VRx dive
computer will give and allow specific conservatism factors to be tried out on the PC
before choosing the right ones for a dive on the VRx. The PC software also gives print
VR Dive Computer Operations Manual 2009 rev E 28/01/2009
35
To Next Page
Loading...