So you want to purchase a Decompression Computer...

[DCBC]

I can't answer the poll, because none of the answers fit. I plan my dives using Ratio Deco. I wear a Liquivision X1 running V-planner, which is VPM-B, with the conservativism set at +3. This generates profiles that are fairly similar to my RD profiles in total stop time, although the X1 usually wants more time shallow. At any rate, if the dive is executed as planned, the computer is happy. I figure the gauge is a last-ditch piece of insurance against either a dive that for some reason is completely different from what I planned, or a dive where something has reduced my processing power to where I need to lean on something else to do the math. (It's also kind of interesting to look at it on cave dives, where the profiles are often quite odd and one wonders if average depth use is really all that valid.)

That's a good choice Lynne, the RD and VPM-B are very close and the X1 will be useful when using a non-standard bottom mix or diving Deep-Air (which isn't likely anyway)

 

[ajduplessis]

.....My computer uses Buhlman with GF. I set it to +3 conservancy...

I was not aware that GF uses +1,2,3 but rather percentages of the high/low portions of the dive such as 30/85 that controls time spend deep /shallow stops. What software and computer do you use?

 

[BlackPatch]

I use an old UWATEC Aladin Pro Nitrox.
This Uses the Buhlman ZH - L 8 Model.

I back it up with my Tables.

Conservancy can be set, unfortunately, I do not have the interface cable to allow me to do this and have been unsuccessful in locating one for the PDC.

Overall I am very happy with the PDC but treat it with respect known it is a prediction not an actual representation of events.

Generally I stay 8 to 10 mins less at a given depth than the max times given within the tables and avoid exertion.

 

[waterpirate]

I dive a cochran set to 0 conservancy, to keep track of the bottom portion of the dive. When it comes to ascent and deco, I use a variant of ratio deco based on what I see generated on vplanner, and pad the conservancy based on the dive. For lack of anything better to do on the hang, I compare them and think about what ifs.
Eric

 

[Dr. Lecter]

If it's a dive worth planning in advance, I use V-Planner and back it up with a Petrel running VPM-B. Conservatism is set anywhere from +2 to +4 depending on depth/time (after receiving a painful rebuke from my upper arms for using +2 for a long exposure on air below 200' I decided to invest extra minutes in deco time for future such exposures).

Lately I've been playing with a combination of slightly extending my deeper stops, even at the expense of additional shallow time, and using a lower conservatism (+3 down to +1) VPM-B backstopped by a low (70 or 75) surfacing GF as a way to extend my shallow stops...it's resulted in me feeling a lot better after longer, deeper dives.

 

[AfterDark]

I use a computer as backup and tables as primary. Whichever is more conservative I go with.

 

[Doppler]

There is yet another option:

On open-circuit, I know what works for me (based on VPM tables), apply it with enough leeway to compensate for variables, and often carry a fourth generation PDC as a fail-safe...

On CCR, I use the unit's built-in computer (Vision electronics using a Buhlmann-based model) change gradient factors to suit conditions, but have a pretty good idea how to finish the dive should the training wheels fall-off during the dive.

But I guess there's not enough room for that in the poll options.

 

[Bombay High]

What is a 4th Generation PDC ?

 

[redacted]

I don't do planned decompression dives. I have never accidentally violated NDLs.

 

[Doppler]

What is a 4th Generation PDC ?

First Generation were clunky monsters which tended to lock users out when NDLs exceeded
Second Generation handled nitrox and still tended to lock users out when moderate deco was exceeded
Third Generation handed mixed gases but padded the algorithm (usually a version of Buhlmann because that model was in the public domain)
Fourth Generation = mixed gas, user adjustable conservatism, follow algorithm without "legal department" padding, options other than a neo-haldanian model