Decompression Modeling

ScubaFeenD · Jul 1, 2010

I am not a technical diver, or at least a diver doing dives past the NDLs. However, after reading deco for divers I have discovered an interest in decompression, and have been playing around with different programs trying to learn more about dive plans using decompression gases and stops.

I am wondering, what model is favored in the DIR technical community? I will eventually be a GUE tech diver (hopefully) and will see what I like then, but I am just curious what, if any, model is favored. Expounding on reasons for favor would also be very interesting to me.

If no model is favored, and it is more personal preference, that is cool too.

rjack321 · Jul 1, 2010

Decoplanner now uses Buhlmann and VPM (which is very close to a 30/85 GF output in Buhlmann anyway). Both outputs end up so heavily modified in practice that its hard to say either profile is actually "preferred". Deep stop additions, oxygen window time moving, and backgas breaks being the key modifications. What's actually taught in GUE's Tech1 nowadays seems to be a little bit of a moving target. I'm sure all 3 concepts will be there whenever you enroll, but their application varies quite a bit across eras and instructors.

jjones9527 · Jul 2, 2010

I'm the same. I'll do up VPM, Buhlmann and Ratio Deco profiles, average them out and move time around to take advantage of the various theories. Its Frankendeco.

gsk3 · Jul 2, 2010

Frankendeco sounds scary ;-)

Can't you make Buhlmann with GF produce deep stops by lowering the first GF (e.g. 10/85 or similar)?

PfcAJ · Jul 2, 2010

Ya, but it doesn't adjust for o2 window and doesn't always stop you at the point you want. its kinda like shoehorning the math to match what you want to do anyways, imo.

LiteHedded · Jul 2, 2010

and it penalizes you for those deep stops

gsk3 · Jul 2, 2010

Ah. When you add deep stops to a 30/85 model doesn't it penalize you too? Or do you just not tell the model that you're doing the stops?

Isn't there a way to make VPM (or the CVA, Boyle's law variant) generate deep stops as well? Or are they not deep enough?

LiteHedded · Jul 2, 2010

buhlmann in general...
haven't played with vpm too much. we typically just add the stops ourselves. vplanner gives you a lot more flexibility with this stuff than decoplanner does.

gsk3 · Jul 2, 2010

So if Buhlmann thinks you're ongassing, and from what I've seen V-Planner would think you're on-gassing at 80% max depth, then aren't you likely ongassing and therefore adding in the stops without telling the model you're doing it kind of breaks the model?

Not trying to be argumentative here; genuinely interested in all this stuff. Professional hazard I'm afraid.

Rainer · Jul 2, 2010

LiteHedded:
vplanner gives you a lot more flexibility with this stuff than decoplanner does.

I actually disagree with this. I think it's significantly easier to add stops and otherwise modify the schedule in DP than VP. Only issue is that DP won't run on my (native) Mac, so I now turn only to VP when needing to check software. Oh, well...

Decompression Modeling

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