Charlie99
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I'm curious as to reserve gas level used by other divers.
Specifically, what rock bottom reserve do you maintain at various depths. Of particular interest to me are your gas turnpoints for ascent from 100'.
I'm assuming unobstructed free acess to the surface.
I end up with about 1100 psi (28 cu ft) being my rock bottom ascent point, using a couple different independent limits.
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#1. One limit assumes sharing air with an excited buddy. 3cfm, but with relatively fast ascent rate of 50fpm. Added to this is 1 minute of getting our act together on the bottom. If my buddy is someone I know and trust, I may drop this down to 2cfm. There is no "psi" fudge factor in this limit. Hopefully, 3 cfm has enough fudge.
#2. The other one reflects my desired gradual ascent. 20-30fpm, a couple of stops for a couple minutes in 40-50 and 25-35' ranges, then a safety stop that start 15-20' and transitions to 8-10' by the end of 4 minutes. All told, from 60' to surface this requires the same gas as would 20 minutes on the surface.
For this I use an estimate of 0.6cu ft/min, a bit more if cold, or if I've been using more gas than normal so far in the dive.
Rule #1 at 100' requires 12cf at the bottom and 15 for ascent. 1100psi on an AL80. (700psi with trusted buddy)
Rule #2 requires about 5cu ft for ascent (0.75cfm) and 12 for all stops. I expect to use about 700psi, add in 300psi for SPG 0 and it also ends up at 1000psi for ascent.
Specifically, what rock bottom reserve do you maintain at various depths. Of particular interest to me are your gas turnpoints for ascent from 100'.
I'm assuming unobstructed free acess to the surface.
I end up with about 1100 psi (28 cu ft) being my rock bottom ascent point, using a couple different independent limits.
----------------------------
#1. One limit assumes sharing air with an excited buddy. 3cfm, but with relatively fast ascent rate of 50fpm. Added to this is 1 minute of getting our act together on the bottom. If my buddy is someone I know and trust, I may drop this down to 2cfm. There is no "psi" fudge factor in this limit. Hopefully, 3 cfm has enough fudge.
#2. The other one reflects my desired gradual ascent. 20-30fpm, a couple of stops for a couple minutes in 40-50 and 25-35' ranges, then a safety stop that start 15-20' and transitions to 8-10' by the end of 4 minutes. All told, from 60' to surface this requires the same gas as would 20 minutes on the surface.
For this I use an estimate of 0.6cu ft/min, a bit more if cold, or if I've been using more gas than normal so far in the dive.
Rule #1 at 100' requires 12cf at the bottom and 15 for ascent. 1100psi on an AL80. (700psi with trusted buddy)
Rule #2 requires about 5cu ft for ascent (0.75cfm) and 12 for all stops. I expect to use about 700psi, add in 300psi for SPG 0 and it also ends up at 1000psi for ascent.