An Experiment

[Kern]

Yes, square profiles. I agree that bubble models are more conservative in general, but I seem to be missing the extreme differences in run times on square profiles.

For the 40 mt. dive below my PADI table gives me a 9 min. NDL + 3 min. ascent + 3 min SS = 15 min. RT.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0m
Conservatism = Nominal

Dec to 40m (2) Air 15m/min descent.
Level 40m 6:20 (9) Air 1.04 ppO2, 40m ead
Asc to 6m (12) Air -9m/min ascent.
Stop at 6m 1:13 (14) Air 0.34 ppO2, 6m ead
Surface (14) Air -9m/min ascent.

Off gassing starts at 20.2m

OTU's this dive: 11
CNS Total: 3.7%

981.9 ltr Air
981.9 ltr TOTAL

For the 35 mt. dive below my PADI table gives me a 14 min. NDL + 3min. ascent + 3 min SS = 20 min. RT.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0m
Conservatism = Nominal

Dec to 35m (2) Air 15m/min descent.
Level 35m 11:40 (14) Air 0.94 ppO2, 35m ead
Asc to 6m (17) Air -9m/min ascent.
Stop at 6m 3:47 (21) Air 0.34 ppO2, 6m ead
Surface (21) Air -9m/min ascent.

Off gassing starts at 21.7m

OTU's this dive: 13
CNS Total: 4.6%

1352.5 ltr Air
1352.5 ltr TOTAL

For the 30 mt. dive below my PADI table gives me a 20 min NDL + 2 min. ascent + 3 min SS = 25 min. RT.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0m
Conservatism = Nominal

Dec to 30m (2) Air 15m/min descent.
Level 30m 18:00 (20) Air 0.84 ppO2, 30m ead
Asc to 6m (22) Air -9m/min ascent.
Stop at 6m 6:20 (29) Air 0.34 ppO2, 6m ead
Surface (29) Air -9m/min ascent.

Off gassing starts at 20.6m

OTU's this dive: 15
CNS Total: 5.0%

1707.5 ltr Air
1707.5 ltr TOTAL

Maybe someone with a computer running RGMB would like to post profiles from their DC for the above dives.

 

[gcbryan]

Check your setting for V-Planner. I was getting crazy numbers and it turned out that somehow the elevation setting was at 7,000ft or something like that even though I had sea level checked in another section of the config menu.

In the past, I have only used V-Planner for decompression dives. Not long ago I fed a number of square profiles that would be within NDLs on any dive table into the program. In each one, V-Planner required surprisingly substantial deco stops.

I find that puzzling.

I do not believe a computer like the X-1 that uses V-Planner is representative of the PDCs that are used by 95% of the divers who use computers (Suunto, Uwatec, Aeris, Oceanic, Sherwood, etc.)