Multideco question

[Agility]

When trying to recalculate the profile http://www.scubaboard.com/forums/attachment.php?attachmentid=206247&d=1428695906 posted in the thread http://www.scubaboard.com/forums/ne...ncident-due-battery-change-dive-computer.html

I played around with my Multideco on Android and found that using
GF 50/70 on Air for a first dive (SI > 5d) the charted dive with a short dip to to 30m and then staying at 23m for 36 minutes gave me the following runtimes:

depth stop run
dsc . 30 - 1
lvl ... 30 4 5
asc . 23 - 5
lvl ... 23 36 41
asc . - - 42

a dive within NDL

increasing bottomtime on the 30m part by 1 minute resulted in

depth stop run
dsc . 30 - 1
lvl ... 30 5 6
asc . 23 - 6
lvl ... 23 36 42
asc . 3 - 42
stop . 3 24 67
asc . - - 68


so 1 additional minute was penalized with 24 minutes of deco

I was curious to see how much additional deco a further increase of bottom time would incur

depth stop run
dsc . 30 - 1
lvl ... 30 7 8
asc . 23 - 8
lvl ... 23 36 44
asc . 3 - 44
stop . 3 26 71
asc . - - 72

so going from 4 to 5 minutes costs 24 minutes of deco, but staying there longer (7 instead of 5) minutes only adds minimal deco.

Is this a flaw in the software?
I will not dive this profile, I just want to learn.

 

[Nirvana]

I think you may have misread the data concerning the first plan. When I try the profile on Multideco, it gives me 24min of deco after ascending from 23m, for a total dive time of 68min. Are you sure it was "surface" you saw at 42min?

 

[Agility]

No, I rechecked it after finding the slow increase in deco obligation adding singele minutes to the deep portion of the dive.
There is another big leap between 9 and 10 minutes (leaving all other parameters the same)

9 min @30m with
36min @23m following gives me
28 min deco @3m

10min @30m with
36min @23m following results in
11min @6m and
22min @3m with a RT of 81min

 

[Nirvana]

It is strange. The results I get from planning in Multideco on my computer are different from yours. There is no "leap" in deco time by adding one minute to bottom time. On your second example, the increase I get is of three minutes of deco. I get the exact same result when planning with iDeco Pro on my phone.

I think there may be a problem with your software. Perhaps a bug in the mobile version of Multideco, perhaps you inadvertently changed a setting that somehow gives these strange results. Have you tried planning the dive on another device, or at least another software, to check the results?

 

[Agility]

Thank you Nirvana, I had thought the algorithm would be implemented teh same on Android and PC, but you were right, dialling the same values into a freshly downloaded Version of Multideco onto my PC I found different values.

MultiDeco 4,01 by Ross Hemingway,
ZHL code by Erik C. Baker.


Decompression model: ZHL16-C + GF


DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 375m (c)
Conservatism = GF 50/70


Dec to 30m (1) Air 18m/min descent.
Level 30m 3:20 (5) Air 0,81 ppO2, 30m ead
Asc to 23m (5) Air -30m/min ascent.
Level 23m 36:00 (41) Air 0,67 ppO2, 23m ead
Asc to 21m (41) Air -30m/min ascent.
Asc to 9m (42) Air -9m/min ascent.
Stop at 9m 0:22 (43) Air 0,38 ppO2, 9m ead
Stop at 6m 1:00 (44) Air 0,32 ppO2, 6m ead
Stop at 3m 21:00 (65) Air 0,26 ppO2, 3m ead
Surface (66) Air -3m/min ascent.


OTU's this dive: 18
CNS Total: 7,0%


3190,4 ltr Air
3190,4 ltr TOTAL




DIVE PLAN COMPLETE



I will submit a bug report

 

[rossh]

Hi,

I think you will find the issue is your settings. Installing a fresh program does not erase the prior settings configuration. I see the plan above has some odd things. 30m / min ascent rate. Maybe more.

If you reset the configuration - go to bottom of the config screen, press reset button - I think you will find the plan works out better for you.

 

[Agility]

Thank you for taking your time,
after resetting and then changing to metric units again and entering GF 50/70 and ZH-Lc I get the following results for 5 or 6 min of the deep part of the dive :

 

[rossh]

Please contact product support below, so we can look into the settings more closely.

support@hhssoftware.com