How to Know When To Start Heading Up

[ReadyDiver]

How do you know when to start heading up on a dive? I understand people use up air at different rates and the deeper you are the faster you use up your air supply. I never know at what psi I should start heading up to end my dives. I am always with an instructor or my Dad and they seem to know when to head up to the surface. I guess i just haven't dove enough to estimate how much air I will need to reach the surface ending my dive with still around 500psi left in my tank. I have an uwatec aladin prime dive console that I love but can't understand how to know when to head up. Is there a general rule of thumb on when to head up?
Any help would be greatly appreciated.

 

[msmith304]

Just plan your dive and stick to your turnaround plan, and until you get comfortable and get some practice keep eyeballing your gauges. Don't wait until you're at 500psi to turn around, when you start getting below 1000 or so go ahead and signal your buddy and make preparations to go up. Even experienced divers make it a constant ritual to eyeball their gauges just to be sure. I'd hate to miss an air leak or something and suddenly not have air. Try to think of your last 500 psi as your Mom/Dad/Spouse/Childs air. Its not necessarily air for you to breathe on the way up- its emergency air for your Mom/Dad/Spouse/Child to be sure you come home.

 

[diver 85]

Depends upon how deep you are when calling a dive due to air/gas........

PLUS, IMO, you need a lot more training to become a real certified diver.....(this is very basic stuff you are talking about------I think)......

 

[D_B]

here is Lamont's info on how to calculate how much air you need for the dive your going to do ... Rock Bottom and Gas Management for Recreational Divers

for min gas to start your ascent .. a quick rule of thumb I use his suggestion of 10 X depth in feet + 300psi (Al80, or HP100) ... that would be 1100psi in a Al80 at 80ft
and it's a good idea when new to not dive your tank deeper than it's CF rating .. 80CF = 80ft

 

[TMHeimer]

In Deep Diver course I was taught to have 100 PSI for every 10 feet of ascent. Ei. If you're at 100 feet start up with 1000 PSI.

 

[Atomic_Diver]

Depending on your SAC rate you could head up at 550psi and make it to the surface at 500psi, or if your SAC rate is bad you my be better off starting up at 900psi, I don't know the way you dive, but considering your a new diver and the max depth allowed for you is 60' (unless your in a compleate state of panic) I would say 800psi would be a good turn around pressure for you, but you know play around with it a bit, if you find you need more pressure to surface at 500 then increase your turn around psi, but if you need less then do the opposite.. Anyway hope this helps- Safe Diving!

 

[Atomic_Diver]

Another thing to consider is your NDL on thoes deeper dives, if you it is possible to have enough gas on a deeper dive that you exceede your NDL, when I started diving and was doing deeper dives I would follow the Rule of Thirds for both my Gas, and NDL, for an example lets say you have 3000psi in your tank, and 60 mins of NDL: You use 20 mins of NDL to head out and explore the dive site, 20mins to get back, and 20 mins for reserve in case something happens, also you use 1000psi of your gas to head out and explore, 1000psi to head back, and 1000psi for reserve- Overall you are going to turn around either after you use 1000psi (leaving 2000psi left), or after 20 mins of the dive (leaving 40 mins left) which ever occurs first is when you turn around.....

 

[idocsteve]

but considering your a new diver and the max depth allowed for you is 60' (unless your in a compleate state of panic)

The 60 foot limit for OW certified divers is a "recommendation" not an enforceable rule.

 

[scubafanatic]

The 60 foot limit for OW certified divers is a "recommendation" not an enforceable rule.

...actually most dive ops DO enforce depth limits, de facto 'scuba police'.

 

[idocsteve]

...actually most dive ops DO enforce depth limits, de facto 'scuba police'.

On a recent cruise we made port at Cozumel and Caymans. I arranged dives with Ops in both locations, both well known and highly respected, their names come up quite often on this board.

My girlfriend was newly certified and another in our group was a "Padi Scuba Diver" (for those who don't know, thats a limited certification...40 foot max and only under direct supervision of a qualified instructor).

We went to 80+ feet in Cozumel and we were down to over a 100 feet in Caymans. If I hadn't stopped her, my girlfriend would have happily and obliviously continued down the wall to who knows how deep.

There was nothing close to direct supervision of any of the divers. I'm not complaining, the divers were great and there were no problems, however that is typical of my experience.