Posted by PTF on April 10, 2001 at 14:02:36:
In Reply to: "I promise I'll demonstrate a safer way to dive the Moody" MHK said posted by Steve on April 10, 2001 at 12:28:02:
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 50 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
100 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 for your questions and discussion