What air level indicates your dive is done?

[raxafarian]

you mean you're not supposed to suck a vacuum on your tank?

 

[TJO]

I use 1/3 of the tank to get somewhere, 1/3 to get back, and the last 1/3 for the safety stop + as a reserve (as a rule).

 

[JustJules]

I would figure it like this:

ascent from 70 to 20 feet=100 sec
call it 2 min at avg of 2.5 ata
assume .5 SAC that is 5cuFt per diver

PLUS 3 min at safety stop plus ascent to surface
is 3cuft per diver (with fudge)

that is 8cu/FT per diver, or 16 total.

However, the safety stop (IMO) is something I will bypass in a share air emergency. A rock bottom for me from 70 feet in good diving conditions is 10cuFt, which is 300psi with a HP120 or 400 with an AL80. This is a good fudge for my buddy and I, as her SAC is around .33 and mine is .51.

We increase this for weather, viz, currents, depth, temperature and other factors. I set the alarm on my computer to give me 300psi at the surface with a 120. This usually causes me to begin ascent at around 550 or so from 60 feet.

 

[exnewwavedivers]

Normally, if I want to return to the dive boat, first person to reach half tank means we all start going back to the boat.

In dives shallower than 60ft, I normally would set 500-750 PSI and deeper than 60ft, 1000-1200 PSI as our turn back time and begin ascent.

 

[sdexcalibur]

I have yet to go past the 40 mark. I do lot of shore diving. Most places are no more than 20 feet. Usually around the 700-500 mark were done.

 

[Ian Wigg]

I've been taught to hit the surface with a minimum of 50 bar in the tank.

 

[bwerb]

ascending. I usually have more than enough air for safety stops and a good reserve. I have not taken a tank back with less than 300psi.

 

[SSIdiver02]

It all depends on what depth you are at, and whether doing a decompression dive or not.

 

[Big-t-2538]

I think that this completely depends on depth. If I am 80 ft down, I'm going to start my ascent when someone hits 1100lbs. If I am diving much shallower...say 40 ft....I probably won't start my ascent until someone in my group is at about 800lbs. Really a function of depth, who is consuming more air, and how comfortable the divers you are with are.

However, my normal buddy always have a back-up plan for our "technical "training dives....deep as we can for as long as we can....then inflate the BC and shoot the the surface like a rocket....I think our record is someone launching a good 8 feet out of the water....:haha:

 

[bottom_sucker]

weight_for_me once bubbled...

.....that would be me.....or Bottomsucker....

I am slowly improving
and it helped with Reg servicing resulted in new screen and improved air flow.