"Guided" 200' dive with a single AL80?
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Tigerman
Contributor
Especially if theire vacation divers with 10 dives a year, all of which happens during their 14-day caribbean vacation..Yeah, but you're probably a hoover and they all have little girly lungs!
Hoosier
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Yeah, but you're probably a hoover and they all have little girly lungs!
So, I will bring a double to catch up their girlie lungs.
1_T_Submariner
Contributor
Lucky, this time.
ianr33
Contributor
It depends on the software or table used as well. For example with Dplan using standard 30/85 GF's, a 60 fpm descent rate and a 30 fpm ascent rate I get:
Descent to 200ft (3:20)
Level 200ft 5:00 (9)
Asc to 60ft (13) Air -30ft/min ascent
Stop at 60ft 1:00 (14)
Stop at 50ft 1:00 (15)
Stop at 40ft 1:00 (16)
Stop at 30ft 2:00 (18)
Stop at 20ft 3:00 (21)
Stop at 10ft 5:00 (26)
Surface (26).
Off gassing starts at 90ft
Gas Used 21% 47 cu ft (RMV=.6 for bottom and .4 for deco)
And if do it the old fashioned way with the decent included in the bottom time rather than assuming 5 min actually at 200 ft, I get:
Descent to 200ft (3:20)
Level 200ft 1:40 (5)
Asc to 40ft (10) Air -30ft/min ascent
Stop at 40ft 1:00 (11)
Stop at 30ft 1:00 (12)
Stop at 20ft 1:00 (13)
Stop at 10ft 1:00 (14)
Surface (14).
Off gassing starts at 60ft
Gas Used 21% 24 cu ft
Which means with an RMV of .6 on the bottom and .4 on deco, you could theoretically do it with a 30 cu ft pony.
The US Navy tables are even more liberal and require only a 1 minute stop at 10 ft. (and 5 minutes at 190' is a no deco dive!)
This is to liberal for my tastes, but on the other hand too much conservatism can be a bad thing on a short dive (+3 or +4 on VPlanner for example) as you spend too much time too deep and essentially on-gas during deco rather than off gas.
The points being
1. yes you could do it on an 80 (easily) but,
2. the real threat here is not so much the deco or the AL 80, but rather the combination of the two with regard to the execution of a deco dive without an adequate redundant gas supply to ensure you can ascend and do the required deco if your primary gas supply failed at the end of your bottom time.
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You all think that we were all on single 80's? You think we ALL were at 199'? The fact is I and the other instructor were on doubles. I was the only one that hit 199' and for :30 seconds. The others had max depts of 175', 165', and 160'. Julio in our group used only one tank. Jennifer shared air with us for the last :03 of the deco-stop. I barely used my second tank as well as Sean, the other instructor in doubles. We all are/were very good on our air and highly experienced. Some of you make out like I am taking beginners down to the 150' marker...and that's just not the case. And no...this was not a PADI dive. This was 4 very experienced divers doing a deco dive. We had all 4 done deco diving before. I understand everyone's concern, and will take all into consideration. But..if it makes you all feel better...I won't do that dive ever again.
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