Algorithms

[MikeFerrara]

I don't have any deco software with me. I'll have to wait till this evening to try it.

 

[O-ring]

MikeFerrara once bubbled...
I don't have any deco software with me. I'll have to wait till this evening to try it.

...if you want to know now you can PM me the profile stuff..

 

[MikeFerrara]

O-ring once bubbled...

...if you want to know now you can PM me the profile stuff..

Run some variations of the 170 for 20 example profile on the link that WYDT provided to see if you can approximate the 20 ft stop time. Also, GI's isn't using any software is he?

 

[O-ring]

170 20
110 1
100 1
90 1
80 1
70 1
60 1
50 1
40 1
30 2
20 9
20 to surf 6
0

I noticed he lengthened his 70' stop to let that 50/50 get in there...looks like he is stopping for about 3-4 mins.

Nevermind, I can't do it...I tried lengthening all those stops in the middle to 3 minutes like GI is doing, but that screws up the 20' stop. He has to be modifying the decoplanner output (IMHO). If I stick to the 20' stop I got originally, that looks like the tail end of his deco. If I then decide to spend 3 minutes at each stop from 70' until 20' instead of the decoplanner 1 minute stops, it looks pretty close. But...why would he be doing that? Is that just a really molasses slow ascent?

 

[WreckWriter]

What mix and what deco gasses did you use?

 

[WreckWriter]

V-Planner 3.10 by R. Hemingway, VPM code by Erik C. Baker.

Decompression model: VPM-B

DIVE PLAN
Surface interval = 2 day 0 hr 0 min.
Altitude = 0ft
Conservatism = Nominal

Dec to 170ft (3) on Trimix 18.0/45.0, 50ft/min descent.
Level 170ft 16:36 (20) on Trimix 18.0/45.0, 1.11 ppO2, 62ft END
Asc to 100ft (21) on Trimix 18.0/45.0, -60ft/min ascent.
Asc to 90ft (21) on Trimix 18.0/45.0, -30ft/min ascent.
Stop at 90ft 0:30 (22) on Trimix 18.0/45.0, 0.67 ppO2, 25ft END
Stop at 80ft 1:00 (23) on Trimix 18.0/45.0, 0.62 ppO2, 20ft END
Stop at 70ft 5:00 (28) on Nitrox 50.0, 1.56 ppO2, 32ft END
Stop at 30ft 3:00 (32) on Nitrox 50.0, 0.95 ppO2, 7ft END
Stop at 20ft 10:00 (42) on Oxygen, 1.60 ppO2, 0ft END
Asc to sfc. (42) on Oxygen, -30ft/min ascent.

Off gassing starts at 130 ft

OTU's this dive: 56
CNS Total: 37.2%

84.3 cu ft Trimix 18.0/45.0
11.8 cu ft Nitrox 50.0
8.2 cu ft Oxygen
104.3 cu ft TOTAL


DIVE PLAN COMPLETE

 

[O-ring]

WreckWriter once bubbled...
What mix and what deco gasses did you use?

It was 170' for a 20 min BT with 20/35 as a bottom mix...using only 50/50 for deco. They were messing around and trying to emulate one of GI3's curves on that website posted earlier in the thread...I got interested and tried it.

 

[MikeFerrara]

I was just trying to use the procedures GI outlines in his articles to recreate the example profiles he gives and I can't duplicate them.

 

[O-ring]

MikeFerrara once bubbled...
I was just trying to use the procedures GI outlines in his articles to recreate the example profiles he gives and I can't duplicate them.

He says in the first article to do your first stop at 80% of the max depth in ATA rounded up... so at 170, that's about 6 ATA * .80 = 5 ata = 130'. His first stop on the graph is at 120'...

Here's something of his I found about doing dives in the ~170' range (http://home.earthlink.net/~toddclagett/decocurves/DecoCurves.htm)

I would make the following changes: slower decent, then after 20 at the
bottom, ascent at 30 fpm, consciously stopping every ten feet to achieve
this, then stop at 120-80 for 30 seconds each.

At 70, the gas switch, I would do 3 minutes to get the full effect of the
switch. See the post that talks about circulation time.
The 3 minutes each at 60,50,40
5 at30
8 at 20
ascend to 0 in 3 minutes

I notice you make a comment about the line. Get in the habit of consciously
stopping every ten feet to insure the proper ascent rate. Coming up from
depth too fast is what gives you the subclinical symptoms hours after the
dive. You trap gas in poorly perfused areas and these later swell and react,
the bubbles in them grow, the reaction presses on nerves, and you get things
like numbness in some extremities while you are sleeping that night - not a
cns hit, a cns manifestation. Skin bends would be a more obvious consequence
of skipping deep stops.

 

[WreckWriter]

O-ring once bubbled...

It was 170' for a 20 min BT with 20/35 as a bottom mix...using only 50/50 for deco. They were messing around and trying to emulate one of GI3's curves on that website posted earlier in the thread...I got interested and tried it.

Odd mix. here's what V-planner gives. note the off gassing point is said to be 124.5':

Dec to 170ft (3) on Trimix 20.0/35.0, 50ft/min descent.
Level 170ft 16:36 (20) on Trimix 20.0/35.0, 1.23 ppO2, 83ft END
Asc to 100ft (21) on Trimix 20.0/35.0, -60ft/min ascent.
Asc to 90ft (21) on Trimix 20.0/35.0, -30ft/min ascent.
Stop at 90ft 0:30 (22) on Trimix 20.0/35.0, 0.74 ppO2, 37ft END
Stop at 80ft 1:00 (23) on Trimix 20.0/35.0, 0.68 ppO2, 31ft END
Stop at 70ft 5:00 (28) on Nitrox 50.0, 1.56 ppO2, 32ft END
Stop at 30ft 2:00 (31) on Nitrox 50.0, 0.95 ppO2, 7ft END
Stop at 20ft 12:00 (43) on Nitrox 50.0, 0.80 ppO2, 1ft END
Stop at 20ft 5:00 (48) on Trimix 20.0/35.0, 0.32 ppO2, 0ft END
Stop at 20ft 1:00 (49) on Nitrox 50.0, 0.80 ppO2, 1ft END
Asc to sfc. (49) on Nitrox 50.0, -30ft/min ascent.

Off gassing starts at 124.5 ft