Improving Ascent/ Safety Stop Practices

[cmalinowski]

Check out the 5 Minute Neurological Exam HERE.

So, if I pass all of those tests, life is grand? Man, maybe i've been worrying a little too much. That just doesn't seem right.

I guess the questions still exists in my mind though: Is there such things as a small hit? Will excess nitrogen from a "small hit" eventually off-gas like normal off-gassing or is it that the bubbles got too big?

I'm going to search a little more. If I can't find my answers in the archives of SB, then I'll move to another thread.

 

[RTodd]

So, if I pass all of those tests, life is grand? Man, maybe i've been worrying a little too much. That just doesn't seem right.

I guess the questions still exists in my mind though: Is there such things as a small hit? Will excess nitrogen from a "small hit" eventually off-gas like normal off-gassing or is it that the bubbles got too big?

I'm going to search a little more. If I can't find my answers in the archives of SB, then I'll move to another thread.

It has been a while so the timing is a guess, but the hyparbaric docs told me somewhere in the 24 hour range the bubbles are gone. (It may be shorter than that) After that, you are treating damage sort of like wound care which is one of the main uses for chambers.

Yes, you can have minor hits that never get treated. Post-dive fatigue is a sign of nitrogen having done some (probably small) amount of damage that your body is recovering from. Those in the "amateur saturation diving" end of the sport take minor type Is regularly without seeking hyparbaric treatment.

 

[pt40fathoms]

http://www.hhssoftware.com/v-planner/index.html is the one I assume the other poster was talking about when referring to V-planner. Also can be accessed via www.v-planner.com . It uses the variable permeability model, which is a dual phase model developed by Yount and Hoffman.
The V-planner author, Ross Hemingway is here ocassionally, and also on thedecostop. Before adapting the VPM code to make Vplanner, he did put out the Buhlman based Zplanner.

There are quite a few Buhlman or neoHaldanian programs out there ..... the older GAP program, DDPLAN, Dplanner, Decoplanner, Zplanner and a host of others, so I can't eliminate the possibility that there is a Buhlman program called V-planner, but that's not what comes to mind with most people. To the best of my knowledge, Vplanner has never been anything other than VPM based, although it has changed from the original VPM model to the VPM-B model.

Charlie

p.s. The DiveRite sells the Voyager deco software, perhaps that is the one that you are thinking about matching up with the ZHL-16 based Nitek.

I must have been having a "moment of cloudiness" as opposed to a "moment of clarity". Because just as I was reading your (p.s.) it struck me that I was in fact thinking about Voyager and not V-Planner.....DOH... :11:

Thanks for reply.

 

[lamont]

So, maybe I'm just abusing how v-planner should be used here, but here's two profiles that I just ran which only differ in the ascent speed. With the 20 fpm ascent speed you get 3 @ 10, but with 100 fpm ascent you get 1:54 @ 10.... Also, here's a table of what I get for stop times vs. ascent rates just playing with that variable:

100 1:54 @ 10
90 1:47 @ 10
80 1:38 @ 10
70 0:26 @ 10
60 2:10 @ 10
50 1:48 @ 10
40 :30 @ 20, 2:00 @ 10
30 :40 @ 20, 2:00 @ 10
20 3:00 @ 10
10 5:00 @ 10

Wierd...


-Planner 3.61 by R. Hemingway, VPM code by Erik C. Baker.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 120ft (6) Nitrox 32 20ft/min descent.
Level 120ft 13:00 (19) Nitrox 32 1.48 ppO2, 99ft ead
Asc to 20ft (24) Nitrox 32 -20ft/min ascent.
Stop at 10ft 3:00 (27) Nitrox 32 0.42 ppO2, 4ft ead
Surface (27) Nitrox 32 -20ft/min ascent.

Off gassing starts at 61.3ft

OTU's this dive: 33
CNS Total: 14.2%

72.2 cu ft Nitrox 32
72.2 cu ft TOTAL

V-Planner 3.61 by R. Hemingway, VPM code by Erik C. Baker.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 120ft (6) Nitrox 32 20ft/min descent.
Level 120ft 13:00 (19) Nitrox 32 1.48 ppO2, 99ft ead
Asc to 10ft (20) Nitrox 32 -100ft/min ascent.
Stop at 10ft 1:54 (22) Nitrox 32 0.42 ppO2, 4ft ead
Surface (22) Nitrox 32 -100ft/min ascent.

Off gassing starts at 64.8ft

OTU's this dive: 30
CNS Total: 12.7%

62.2 cu ft Nitrox 32
62.2 cu ft TOTAL


DIVE PLAN COMPLETE

 

[Charlie99]

Wierd...


Level 120ft 13:00 (19) Nitrox 32 1.48 ppO2, 99ft ead

It might be that 6 minutes descent plus 13 minutes at 120' on EAN32 doesn't load you up enough that a high ascent rate causes significant bubbling.

What happens if you repeat your runs, but with something more like 18 or 20 minutes level at 120'? Or maybe just running the same profile as before, but with conservatism cranked up a couple more notches.

I don't have V-planner on this computer, but my guess is that you would find that that both very fast and very slow ascent rates would require longer 10' hangs, with a sweet spot or range of ascents that minimizes 10' time.

 

[RTodd]

It might be that 6 minutes descent plus 13 minutes at 120' on EAN32 doesn't load you up enough that a high ascent rate causes significant bubbling.

What happens if you repeat your runs, but with something more like 18 or 20 minutes level at 120'? Or maybe just running the same profile as before, but with conservatism cranked up a couple more notches.

I don't have V-planner on this computer, but my guess is that you would find that that both very fast and very slow ascent rates would require longer 10' hangs, with a sweet spot or range of ascents that minimizes 10' time.

You guys are placing too much reliance on what the theoretical model tells you.

 

[Charlie99]

You guys are placing too much reliance on what the theoretical model tells you.

Don't worry, in real life I just rely upon my guesses.

 

[lamont]

Don't worry, in real life I just rely upon my guesses.

Heck, I usually just hit the surface pretty quick, and then if I start to feel a bit bent, I head back down to do a little more deco. No guesswork involved, no reliance on models...

I'll play with it a bit more and see what happens. You might be correct that bouncing to 120' only loads up fast compartments, so you can surface pretty rapidly without the model showing you bubbling. Results might be different for a dive at 60' to the NDLs which would load up slower compartments...