Shearwater fans.....question?

[DA Aquamaster]

VPM-B does not use GFs, just conservatism settings of 0 to +5.

If you unlock the VPM-B on a Shearwater, you can however select either the Bhulman or VPM-B algorithm.

One reason I opted to unlock VPM-B on one of my predators is to run the same basic program as a team mate using VPM-B on her computer. With the conservatism set the same, the same gasses in use and the same basic dive profile, it gives me a fairly accurate indication at any point in the dive, what her computer is probably saying. On some dives where penetration gas is not the limiting factor we'll turn the dive based on a certain amount of deco obligation at max penetration knowing, based on past dives/profiles, about how much deco obligation will be accrued by the time we exit the cave/start the deco. That's where the numbers can differ a bit between the GF and VPM-B computers.

 

[manni-yunk]

VPM-B does not use GFs, just conservatism settings of 0 to +5.

If you unlock the VPM-B on a Shearwater, you can however select either the Bhulman or VPM-B algorithm.

.

How sure are you? Isnt there is ANOTHER choice....Buhlman with GFS, VPM-B - and VPM-B GFS. If you choose the VPM-B GFS, the software will supposedly choose the decompression ceiling from the more conservative of the VPM-B profile and a Bühlmann ZHL-16C profile.

 

[ianr33]

How sure are you? Isnt there is ANOTHER choice....Buhlman with GFS, VPM-B - and VPM-B GFS. If you choose the VPM-B GFS, the software will supposedly choose the decompression ceiling from the more conservative of the VPM-B profile and a Bühlmann ZHL-16C profile.

Ah,O.K. I think I understand your point now.

I *think* the way it works is this: Using VPM it's sometimes possible ,depending on the profile, to surface with the GF HI too large. The VPM-B GFS is just an override to make sure this can not happen. i.e it doesn't change the shape of the (VPM) profile really, just extends the shallow stops.

I just dive Buhlman on 30 85 and don't worry about it.

 

[DA Aquamaster]

That's pretty much it. Using two Predators, one running each algorithm, there's no advantage to the VPM-B GFS, and if I only had one, as indicated above, I'd just run Buhlman GFs as the GFs allow a lot more control for "different" profiles with no need for a crutch.

 

[gekodivebali]

No GF on Vpm, just conservatism factors.

---------- Post added January 1st, 2013 at 05:34 PM ----------

Deeper stops on Vpm but shorter deci in the shallows.
I prefer Gf since i know it better. Both a Vpm +2 or 3 or Gf 30/85 should be ok for relatively shallow and short dives. Would add conservatism for longer profiles.