Blackcrusader
Contributor
It is not a specialty in most agencies, but I'd like light back gas deco. 10 minutes of back gas deco adds 50 to 100+% ish more time past NDL in the 80' to 130' range.
hmmm single AL 80 lets plan a 15 minute dive at 40m need 10 mins deco time for a total dive time of 25 minutes. Only need 1055 liters at SAC of 12l/min GF 45/95. Or 40m for 20 minutes need 17 mins of deco time for total dive time of 37 minutes using 1480 liters. All on air. You might get more time past NDL but you end up with shorter dive times doing a square profile whereas a dive to 40m staying within NDL limits and doing a multilevel dive has no set time limit. Of course 12l/mon sac rate is being very generous to most vacation divers. Others on SB have good low gas consumption.
Of course better if you have a 100 or 120 size tank perhaps although I have seen divers struggle with the larger tanks. To add light back gas deco you will want divers to be able to know about their RMV and have two tanks yes?
A 25m dive on 21% for 40 minutes then 17 mins deco time at 12l/min 57 minute dive time 1900 liters of gas.
A 25m dive on 32% for 45 minutes then 6 mins of deco 1920 liters of gas at 12l/min very tight on a single AL 80 need a pony
A 25m dive on 32% for 50 minutes then 9 mins of deco 2200 liters of gas at 12l/min near empty tank lol Need an AL100 plus pony
For me on an AL80 I can do the 25m depth 50 minute dive pls 9 mins deco. At that point I need to ascend to do my deco obligation I would still be at half tank on an AL80. Plenty of gas left to complete deco obligation. Total gas I would need would be around 1500 liters.
Others not sure about them lol.