| AIUI
You need to think in terms of the Buhlmann model inside the VRs.
Every 10 seconds the computer samples depth and looks at the gas you have told it you are breathing and applies that to 16 compartments. When one of those compartments exceeds it's surfacing M-Value you have a ceiling below the water line which is displayed as a standard stop depth. The VRs implement deep stops, so they look at your max depth and the current standard stop depth and insert a series of intermediate stops.
Now you start to ascend. The cieling is roughly ascending, but much slower than you are ascending. Lets say you ascend 1m above the 17m deep stop. The Vr continues to sample depth and the gas you told it you are breathing and it continues to load and unload the 16 compartments accordingly. As you are at 16m it will use that depth in calculations, well about 2.6bar pressure as far as the VR3 is concerned. The shallow stops would be reduced the same as they would on a non-deep stop computer, like an Aladin for instance. After 60 seconds the VR displays a 'use tables' caution and recalculates the remaining deep stops.
Now lets say you ascend early from a shallow stop. What happens to the model is that the hypothetical gas pressures in one or more compartments will exceed the surface M-Values, this is a theoretical bend. However the computer is a machine and does not need evacuating to a chamber. It just sees the compartment loading values have exceeded a significant threshold (the M-Value) and continues to load and unload hypothetical inert into and out of the compartments. Although you happen to be on the surface the display will be showing that you still have several minutes to complete at whatever stop depth you ascended from. The stop time will reduce based on your current depth of roughly 1000 milli bar pressure. I suspect that once on the surface the VR assumes you are breathing air. After (IIRC) 5 minutes it stops displaying the last stop but continues to calculate the hypothetical inert in the compartments.
So whatever you happen to do, the VR just doggedly carries on calculating the loadings in it's compartments, based on sampled pressure and breathing gas selected. If you are still walking you could dive it and it would still tell you the deco requirements of the model it implements.
HTH  |