VPM-B vs Buhlmann GF

[Valery]

Hi guys,
I dive in OC and I have a new X1 with VPM-B and Buhlmann GF, I was wondering which algo would you rather dive, at what conservatism or GF and why?

 

[SeaCobra]

neither, I prefer the RGBM tables, or the GAP software.

Jeff

 

[DA Aquamaster]

I use Deco Planner and DPlan - a Palm based version of Deco Planner and consequently tend to prefer computers with adjustable GFs.

The thing is you can't just pick one set of GF's for every possible dives. To keep it really simple, you can modify the GFs to modify the first stop depth and the time spent at the sallower stops to modify the curve. But what you'd want to use on a deep trimix dive with a fairly short bottom time is different than what you'd want to use on a longer, shallower nitrox dive, so there is no magic set of GFs.

But...once you understand how it works, it is a great way to adjust the conservatism of your dive profile.

 

[Valery]

I use Deco Planner and DPlan - a Palm based version of Deco Planner and consequently tend to prefer computers with adjustable GFs.

The thing is you can't just pick one set of GF's for every possible dives. To keep it really simple, you can modify the GFs to modify the first stop depth and the time spent at the sallower stops to modify the curve. But what you'd want to use on a deep trimix dive with a fairly short bottom time is different than what you'd want to use on a longer, shallower nitrox dive, so there is no magic set of GFs.

But...once you understand how it works, it is a great way to adjust the conservatism of your dive profile.

Thanks since I'm not yet on trimix I couldn't know this part.

 

[rstofer]

If you haven't already done so, you might want to post this over on one of the technical diving forums.

Great computer, by the way!

Richard

 

[battles2a5]

I like both. Like DA states, you need to work w/ the curve on Buhlman GF. Before I got my Shearwater I used VPM-B on +2 for dive planning. I find that 30/85 on shallow dives (up to 50M) and 20/90 on deeper dives (up to 100M) matches up pretty well w/ VPM-B on +2. The shape of the curve is still slightly different but RT's and gas consumption are very comparable.

 

[TMHeimer]

Off topic a bit. Does anyone know what type my Mares 2 is? Bulhman EE washout, Spencer limits, etc. as per the 3 types listed in the PADI DM manual. I've searched the computer manual and come up empty. Also, how would you know which of the 3 types other divers have?

 

[rongoodman]

Off topic a bit. Does anyone know what type my Mares 2 is? Bulhman EE washout, Spencer limits, etc. as per the 3 types listed in the PADI DM manual. I've searched the computer manual and come up empty. Also, how would you know which of the 3 types other divers have?

Often there's no way of knowing, either because the deco model just isn't documented, or because the manufacturer considers it to to be proprietary. There has been lots of speculation, e.g., as to what Suunto's "RGBM" actually means, but no one seems to know for sure. That's one reason why the X1 is such a nice computer--you pick the software you want to run. For some good, readable background on all this, take a look at "Deco for Divers" by Mark Powell.

 

[Kern]

One of the things I like about V-planer is its scaleability. If I use VPM-B at conservative setting 2, I get the sort of curve I think I like, whether I'm doing a 45 mt air dive or an an 80 mt trimix dive. If I was doing very deep, &/or, very long RT, I could set it to VPM-BE & have exactly the same curve as I would with VPM-B until the depths &/or RT, were extended so as to cause the profile to diverge.

I have no real preference however. If my current machine ever becomes a conversation piece/paperweight, I'd get a GF machine & get the desktop software that had the closest resemblance to its output.