All

I've run a few profiles (presented below for fellow deco anoraks) as per   
the example being discussed 300', 25 min ABT, ascent rates 100, 60, 30   
FPM, no deep stops, etc:

My conclusion seems to be two fold:

1. The results seem to bear out Will's statement that the Abyss 120   
(stated as similar to the ZH-L16c) is more conservative than the raw   
Smithers' implementation of the Buhlmann algorithm.  In fact the Abyss   
100 seems closer, though slightly less conservative.
   

2. Its about time our cousins get off the imperial system and onto the   
right-thinking metric system.

David Shimell
Project Manager, Sequent Computer Systems Ltd, Weybridge, UK
Email: shimell@se*.co*


The same profile and ascent rate on the Abyss 150 gives:

Depth   Time   Total    Gas & Percent
(ft)     at    time
 150     1.0    31.5    O14.0%, N36.0%, He50.0%
 140     2.0    33.7    O14.0%, N36.0%, He50.0%
 130     1.0    34.8    O32.0%, N68.0%
 120     2.0    37.0    O32.0%, N68.0%
 110     2.0    39.2    O32.0%, N68.0%
 100     2.0    41.3    O32.0%, N68.0%
  90     4.0    45.7    O32.0%, N68.0%
  80     4.0    50.0    O32.0%, N68.0%
  70     5.0    55.3    O50.0%, N50.0%
  60     7.0    62.7    O50.0%, N50.0%
  50     9.0    72.0    O50.0%, N50.0%
  40    14.0    86.3    O50.0%, N50.0%
  30    19.0   105.7    O50.0%, N50.0%
  20    25.0   131.7    O100.0%
  10    42.0   174.7    O100.0%

The same profile and ascent rate on the Abyss 100 gives:

Depth   Time   Total    Gas & Percent
(ft)     at    time
 120     1.0    32.0    O32.0%, N68.0%
 110     2.0    34.2    O32.0%, N68.0%
 100     1.0    35.3    O32.0%, N68.0%
  90     2.0    37.7    O32.0%, N68.0%
  80     3.0    41.0    O32.0%, N68.0%
  70     4.0    45.3    O50.0%, N50.0%
  60     4.0    49.7    O50.0%, N50.0%
  50     7.0    57.0    O50.0%, N50.0%
  40     9.0    66.3    O50.0%, N50.0%
  30    14.0    80.7    O50.0%, N50.0%
  20    17.0    98.7    O100.0%
  10    29.0   128.7    O100.0%

The same profile and ascent rate on the Abyss 100 gives:

DECO Stops.
Depth   Time   Total    Gas & Percent
(ft)     at    time
 120     1.0    32.0    O32.0%, N68.0%
 110     1.0    33.2    O32.0%, N68.0%
 100     1.0    34.3    O32.0%, N68.0%
  90     2.0    36.7    O32.0%, N68.0%
  80     2.0    39.0    O32.0%, N68.0%
  70     3.0    42.3    O50.0%, N50.0%
  60     4.0    46.7    O50.0%, N50.0%
  50     5.0    52.0    O50.0%, N50.0%
  40     8.0    60.3    O50.0%, N50.0%
  30    11.0    71.7    O50.0%, N50.0%
  20    13.0    85.7    O100.0%
  10    24.0   110.7    O100.0%

 ----------
From:  owner-techdiver[SMTP:owner-techdiver@aquanaut.com]
Sent:  25 November 1997 18:19
To:  Jon Breazile
Cc:  techdiver
Subject:  RE: THE FACTS: TDI Training Death, 16 April 1997


On Tue, 25 Nov 1997, Jon Breazile wrote:
> William M. Smithers Wrote:
> >No thank you - I like my Buhlmann served straight up, water on
> >the side.
>
> Don't you think you should throw in some deep stops, or do you
> consider it ongassing?

Of course it's a good idea to throw in deep stops, but that's
irrelevant - Pyle-style deep stops are applied post-model - meaning
the model is run, deep stops are added, then the model is re-run.

> Tell us what you would do for a 300 ft.
> dive for 25 min for 14/50.

Glad you asked, but it's moot, because since I went closed-circuit, I   
only
dive Heliox below 150ft, then switch to N2 diluent for deco.

But here's what you get for 300 for 25 on 14/50, with,
then without deep stops, using unadulterated Buhlmann ZHL16c.
This assumes 32%, 50%, and 100% for deco, a 100fpm descent
rate, with an on-the fly switch from 50% to mix at 60ft, and
an ascent rate of 60fpm up to 100, then 30fpm slowing to 10fpm
as you get shallow.  In real life, I'd probably skip the 32%,
and calculate the intermediate stops for mix.

                DIVE PLAN

Waypoint  at  60ft for   0 min on Nitrox 50.0, PPO2 1.408, END 26
Waypoint  at  300ft for  25 min on Trimix 14.0/50.0, PPO2 1.411, END 119
Norm Stop at  120ft for   1 min on Nitrox 32.0, PPO2 1.482, END 90
Norm Stop at  110ft for   1 min on Nitrox 32.0, PPO2 1.385, END 90
Norm Stop at  100ft for   1 min on Nitrox 32.0, PPO2 1.288, END 81
Norm Stop at  90ft for   2 min on Nitrox 32.0, PPO2 1.191, END 73
Norm Stop at  80ft for   2 min on Nitrox 32.0, PPO2 1.095, END 64
Norm Stop at  70ft for   3 min on Nitrox 50.0, PPO2 1.559, END 32
Norm Stop at  60ft for   3 min on Nitrox 50.0, PPO2 1.408, END 26
Norm Stop at  50ft for   6 min on Nitrox 50.0, PPO2 1.256, END 20
Norm Stop at  40ft for   7 min on Nitrox 50.0, PPO2 1.105, END 13
Norm Stop at  30ft for  12 min on Nitrox 50.0, PPO2 0.954, END 7
Norm Stop at  20ft for  14 min on 100% Oxygen, PPO2 1.605, END 0
Norm Stop at  10ft for  27 min on 100% Oxygen, PPO2 1.303, END 0

TOTAL DECO TIME: 79 minutes.
DIVE RUN TIME: 115 minutes.
CNS Total: 85.3%
OTU's: 168

42.1Cu ft of 50.0% consumed.
155.7Cu ft of 14.0/50.0 consumed.
14.7Cu ft of 32.0% consumed.
33.0Cu ft of 100.0% consumed.
245.5Cu ft total open circuit gas consumed.


And with 2 minute Pyle-style deep stops:


Waypoint  at  60ft for   0 min on Nitrox 50.0, PPO2 1.408, END 26
Waypoint  at  300ft for  25 min on Trimix 14.0/50.0, PPO2 1.411, END 119
Deep Stop at  200ft for   2 min on Trimix 14.0/50.0, PPO2 0.987, END 73
Deep Stop at  160ft for   2 min on Trimix 14.0/50.0, PPO2 0.818, END 55
Deep Stop at  130ft for   2 min on Trimix 14.0/50.0, PPO2 0.691, END 41
Norm Stop at  100ft for   1 min on Nitrox 32.0, PPO2 1.288, END 81
Norm Stop at  90ft for   2 min on Nitrox 32.0, PPO2 1.191, END 73
Norm Stop at  80ft for   3 min on Nitrox 32.0, PPO2 1.095, END 64
Norm Stop at  70ft for   3 min on Nitrox 50.0, PPO2 1.559, END 32
Norm Stop at  60ft for   4 min on Nitrox 50.0, PPO2 1.408, END 26
Norm Stop at  50ft for   6 min on Nitrox 50.0, PPO2 1.256, END 20
Norm Stop at  40ft for   9 min on Nitrox 50.0, PPO2 1.105, END 13
Norm Stop at  30ft for  13 min on Nitrox 50.0, PPO2 0.954, END 7
Norm Stop at  20ft for  16 min on 100% Oxygen, PPO2 1.605, END 0
Norm Stop at  10ft for  31 min on 100% Oxygen, PPO2 1.303, END 0

TOTAL DECO TIME: 94 minutes.
DIVE RUN TIME: 129 minutes.
CNS Total: 94.5%
OTU's: 184
47.0Cu ft of 50.0% consumed.
174.5Cu ft of 14.0/50.0 consumed.
12.2Cu ft of 32.0% consumed.
37.0Cu ft of 100.0% consumed.
270.8Cu ft total open circuit gas consumed.

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