Hi all,
I've noticed something odd, first in OSTC-planner, and now I think I've seen it on a dive and I'm wondering if it's something to be worried about or not.
I dive gradient factors at the default settings (30/85?) and it seems like it's possible for the decompression ceiling to rise whilst the diver is on-gassing. That doesn't seem right to me, and I'm wondering if it's a symptom of a bug.
It's easiest to show in ostc-planner. Plan a deep dive at a constant depth for a reasonable time and plot the deco ceiling. In some cases, whilst still on the bottom the deco, ceiling will go shallower, and then go back deeper again.
I thought maybe this was a quirk of ostc-planner, but I think I've now seen it on a dive. Has anyone else seen this? Is it a side effect of gradient factors?
(I'm at work at the moment so I don't have planner here, otherwise I'd post a proper example)
Ceiling popping up
Re: Ceiling popping up
Hi,
dou you see this behaviour when ascending and staying a very long period of time on a deeper stop?
Then it makes sense from my point of view.
Due to different tissues with different speed of saturation / desaturation it might happen that a faster tissue is first desaturating on that particular stop but a slower tissue will saturate over long period of time.
As the ceiling is controlled by the tissue with the highest gas-load this behaviour might happen on a deeper stop.
Or do you see this beaviour when still staying on the bottom?
Then it doesn't make sense for me neither.
Reiner
dou you see this behaviour when ascending and staying a very long period of time on a deeper stop?
Then it makes sense from my point of view.
Due to different tissues with different speed of saturation / desaturation it might happen that a faster tissue is first desaturating on that particular stop but a slower tissue will saturate over long period of time.
As the ceiling is controlled by the tissue with the highest gas-load this behaviour might happen on a deeper stop.
Or do you see this beaviour when still staying on the bottom?
Then it doesn't make sense for me neither.
Reiner
Re: Ceiling popping up
Nope, no deeper stop. I see it whilst still deep.
When I get home I'll try to show an example on the planner.
When I get home I'll try to show an example on the planner.
Re: Ceiling popping up
Here's an example on OSTC-Planner, a 42m dive for 40 minutes on air
[IMG]http://i.imgur.com/9W7y2.jpg[/IMG]
You can see the ceiling getting shallower about the 16 minute mark and the 25 minute mark.
Here's a snippet of the verbose simulation:
[pre]
16:12 42.0m Deco:
15 m : 1 ' 20 '
12 m : 2 ' 22 '
9 m : 1 ' 23 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
16:20 42.0m Deco:
15 m : 2 ' 21 '
12 m : 1 ' 22 '
9 m : 2 ' 25 '
6 m : 14 ' 39 '
0 m : --- ' 40 '
TTS = 24 '
CNS = 9%
16:28 42.0m Deco:
12 m : 2 ' 21 '
9 m : 2 ' 24 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
16:36 42.0m Deco:
12 m : 2 ' 22 '
9 m : 2 ' 24 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
[/pre]
We went from having to do 2 minutes at 15 metres and 1 minute at 12 to 2 minutes at 12 metres. It's similar around 18 metres:
[pre]
24:40 42.0m Deco:
18 m : 2 ' 29 '
15 m : 1 ' 30 '
12 m : 4 ' 35 '
9 m : 5 ' 40 '
6 m : 46 ' 86 '
0 m : --- ' 87 '
TTS = 63 '
CNS = 12%
24:52 42.0m Deco:
18 m : 2 ' 29 '
15 m : 1 ' 31 '
12 m : 4 ' 35 '
9 m : 5 ' 40 '
6 m : 48 ' 88 '
0 m : --- ' 90 '
TTS = 65 '
CNS = 12%
25:04 42.0m Deco:
15 m : 2 ' 30 '
12 m : 3 ' 33 '
9 m : 5 ' 38 '
6 m : 47 ' 86 '
0 m : --- ' 87 '
TTS = 62 '
CNS = 12%
25:16 42.0m Deco:
15 m : 2 ' 30 '
12 m : 3 ' 33 '
9 m : 5 ' 39 '
6 m : 48 ' 87 '
0 m : --- ' 88 '
TTS = 63 '
CNS = 12%
[/pre]
That doesn't seem right to me.
I'm a little confused about the ascent too.
[IMG]http://i.imgur.com/o5st5.jpg[/IMG]
It looks like the first stop is spiking the GF at ~50% (GF Low is 30%) and whilst the GF drops off steadily most of the time it has big vertical drops in the middle of the last 3 stops.
Paul
[hr]
Edit: Images didn't work so turned them into links.
[IMG]http://i.imgur.com/9W7y2.jpg[/IMG]
You can see the ceiling getting shallower about the 16 minute mark and the 25 minute mark.
Here's a snippet of the verbose simulation:
[pre]
16:12 42.0m Deco:
15 m : 1 ' 20 '
12 m : 2 ' 22 '
9 m : 1 ' 23 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
16:20 42.0m Deco:
15 m : 2 ' 21 '
12 m : 1 ' 22 '
9 m : 2 ' 25 '
6 m : 14 ' 39 '
0 m : --- ' 40 '
TTS = 24 '
CNS = 9%
16:28 42.0m Deco:
12 m : 2 ' 21 '
9 m : 2 ' 24 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
16:36 42.0m Deco:
12 m : 2 ' 22 '
9 m : 2 ' 24 '
6 m : 14 ' 38 '
0 m : --- ' 39 '
TTS = 23 '
CNS = 8%
[/pre]
We went from having to do 2 minutes at 15 metres and 1 minute at 12 to 2 minutes at 12 metres. It's similar around 18 metres:
[pre]
24:40 42.0m Deco:
18 m : 2 ' 29 '
15 m : 1 ' 30 '
12 m : 4 ' 35 '
9 m : 5 ' 40 '
6 m : 46 ' 86 '
0 m : --- ' 87 '
TTS = 63 '
CNS = 12%
24:52 42.0m Deco:
18 m : 2 ' 29 '
15 m : 1 ' 31 '
12 m : 4 ' 35 '
9 m : 5 ' 40 '
6 m : 48 ' 88 '
0 m : --- ' 90 '
TTS = 65 '
CNS = 12%
25:04 42.0m Deco:
15 m : 2 ' 30 '
12 m : 3 ' 33 '
9 m : 5 ' 38 '
6 m : 47 ' 86 '
0 m : --- ' 87 '
TTS = 62 '
CNS = 12%
25:16 42.0m Deco:
15 m : 2 ' 30 '
12 m : 3 ' 33 '
9 m : 5 ' 39 '
6 m : 48 ' 87 '
0 m : --- ' 88 '
TTS = 63 '
CNS = 12%
[/pre]
That doesn't seem right to me.
I'm a little confused about the ascent too.
[IMG]http://i.imgur.com/o5st5.jpg[/IMG]
It looks like the first stop is spiking the GF at ~50% (GF Low is 30%) and whilst the GF drops off steadily most of the time it has big vertical drops in the middle of the last 3 stops.
Paul
[hr]
Edit: Images didn't work so turned them into links.