Posted by PTF on April 10, 2001 at 14:25:49:
In Reply to: Refreshed memory posted by PTF on April 10, 2001 at 14:02:36:
let's take a typical dive on the Moody.
All quotes taken out of context. It wouldn't be a true form of this BBS otherwise.
Posted by Steve on April 05, 2001 at 19:31:19:
CASE 1 - Moody on AIR at 15 min BT
CASE 1A
" My plan was 15 minutes because I was making 2 more dives that
day Ace I and Olympic II so I didn't want to push it...... I ascended
to 75' for my deep stop and my deco went up to 13 minutes, so I
didn't get any credit there. Stats are:
max depth .... 146'
time.......... 37 minutes
O2............ 21%
olf........... 6%
air used...... 62 cuft
sac........... .49
psi min....... 59
Deco 40% EAN start 33' for 1 min., 15' for 13 minutes....:"
CASE 1B
Let's first look at Decoplanner with the above profile of air.
Active SAC at 0.49 and resting at 0.50 (it should be less but I am currently
at 0.55 and 0.5). For this dive the profile would like..
depth time %O2 %He Start Time
at depth
146.....15......21......0.......0
90......1.......21......0.......17
80......1.......21......0.......17
70......1.......21......0.......18
60......1.......21......0.......19
50......1.......21......0.......20
40......1.......21......0.......21
30......1.......21......0.......22
20......7.......21......0.......23
0...............................31
gas used is 61 cu ft (close to your actual use), almost close to the profile
you ran. I will let MHK/Walker talk to the purpose of slow ascents/deep
stops, if the so choose.
CASE 2 Moody on mix at 15 min BT:
from MHK "Our team approach is to never exceed an END of 100' and as such we
would normally run a hyperoxic trimix of 25/20."
So, let's do the same dive with trimix of 25% O2, 20% He and use a stage bottle of
50/50 (O2/N2)
depth time %O2 %He Start Time
at depth
146......15......25......20......0
80.......1.......25......20......17
70.......1.......50.......0......18
60.......1.......50.......0......19
50.......1.......50.......0......20
40.......1.......50.......0......21
30.......1.......50.......0......22
20.......1.......50.......0......23
0................................25
back gas used 47 cu ft, deco gas 8 cu ft
Definately worth it if the seas pick up.
CASE 3 Moody at 30 minutes BT
CASE 3A - On Mix
Now lets strap on a pair of doubles and extend to 30 minutes the bottom time
depth time %O2 %He Start Time
at depth
146......30......25......20.....0
90.......1.......25......20.....32
80.......1.......25......20.....32
70.......1.......5.......0......33
60.......1.......50......0......34
50.......1.......50......0......35
40.......1.......50......0......36
30.......2.......50......0......37
20......14.......50......0......39
0...............................54
back gas used/deco gas: 89/19 cu ft
CASE 3B - on Air and less than optimal deco mix
and if we only did this on Air and, eh, 40% nitrox
depth time %O2 %He Start Time
at depth
146......30.....21......0.......0
10.......1......21......0......32
90.......1......21......0......32
80.......1......21......0......33
70.......1......21......0......34
60.......1......21......0......35
50.......2......21......0......36
40.......4......21......0......38
30.......4......40......0......42
20......23......40......0......46
0..............................70
back gas used/deco gas: 101/23 cu ft
A better mix of gas can cut your hang time on this dive by 16 minutes and
if you emplyed a 50/50 instead of 40/60 you could drop another 9 minutes.
So this is a Jump off point