Oxygen Exposure Otu Error On V-planner & Multideco

[Divetech99]

I'm plotting a series of dives to show a friend the oxygen exposure impact of back-to-back dives on Nitrox. Simple sample dives are a series of 10 repetitive dives to 18 meters for 56 minutes on EAN32 with only 1.5 hours SIT in between dives. Purpose is to see the effects of CNS% and OTUs change.

Using V-Planner or MultiDeco on iOS, the OTUs appears to stay unchanged after dive #1, even after plotting a series of 10 dives in a row with 1.5 hours SIT. CNS% seems to compute normally, taking into consideration the 90 minute half time credits. OTUs should be adding up per dive but it's not doing so. Has anyone experienced this? Looks like a serious bug unless I'm missing a config setting.

 

[Ouvea]

Works fine with my Deco Planner (V 3.1.4). Checked both VPM and Buhlman GF20/85.

Dive 1: 46.81 OTU
Dive 2: 93.61 OTU
Dive 3: 140.42 OTU
Dive 4: 187.23 OTU

 

[Divetech99]

Thanks. However on the iOS app of MultiDeco and V-Planner, OTU is stuck at on the first value even after entering repetitive dives.

 

[rossh]

No bugs.

What you are missing is this: CNS only accumulates after the inspired mix is greater than 0.5 ppO2. Your sample dive at 18ft has an inspired mix of 0.49 ppO2... Not quite deep enough to add to the CNS total..

 

[Patoux01]

Your sample dive at 18m has an inspired mix of 0.49 ppO2

Huh? How?

 

[rossh]

Sorry, my mistake. I was thinking in feet, not meters.

Did you make the same mistake when planning? Have the config set to feet and therefore it was 0.49 as per above?

I don't see any error in the iOS program.

dive 1
18m, 56min 32% = 15%CNS
1 hour SI
dive 2
18m, 56min 32% = 25%CNS
1 hour SI
dive 3
18m, 56min 32% = 31%CNS
1 hour SI
dive 4
18m, 56min 32% = 35%CNS
1 hour SI
dive 5
18m, 56min 32% = 38%CNS


Note that the OTU is always a per dive number, and does not accumulate or decay. There is no decay formula for OTU.


I don't see any errors.

 

[Divetech99]

Hi Ross, CNS% seems to be working fine and it appears to factor a 90 minute half time (decay) which is correct per NOAA guidelines.

The issue is OTU. It SHOULD accumulate for a diver to know his total exposure per dive and per day, actually over several days.

Thanks.

 

[Ouvea]

Hi Divetech99:

I apologize, I misread the name of the planning software. Best of luck and safe diving!

O.

 

[JohnnyC]

Mine is showing OTU's per dive, with no cumulative total. CNS percentage is showing cumulatively over the course of the 10 dives. 10 dives, 18m, 56 minutes, 1.5 hr surface interval, GF 30/70

DIVE PLAN #1
OTU's this dive: 45
CNS Total: 15.0%

DIVE PLAN #2
OTU's this dive: 45
CNS Total: 22.6%

DIVE PLAN #3
OTU's this dive: 45
CNS Total: 26.4%

DIVE PLAN #4
OTU's this dive: 45
CNS Total: 28.3%

DIVE PLAN #5
OTU's this dive: 45
CNS Total: 29.2%

DIVE PLAN #6
OTU's this dive: 45
CNS Total: 29.7%

DIVE PLAN #7
OTU's this dive: 45
CNS Total: 30.0%

DIVE PLAN #8
OTU's this dive: 45
CNS Total: 30.1%

DIVE PLAN #9
OTU's this dive: 45
CNS Total: 30.1%

DIVE PLAN #10
OTU's this dive: 45
CNS Total: 30.2%

The software shows the number of OTU's clocked per dive, with no total based on the repetitive dives. In this case, 450 OTU's over the course of the 10 repetitive dives. Daily recommendation of 850 for the first day according to the REPEX table, 750 day 2 with 1400 total, etc.

MultiDeco version 4.10.0 is what I used.

@rossh any thoughts?

 

[Divetech99]

OTUs should accumulate over repetitive dives. Hopefully this gets fixed.