Low air limit?

[gbrandon]

At what PSI do most of you decide to end your dive? (assuming the dive is less than 100 feet)

I was just curious as to the average. Also, What is the average PSI you have left when you are at the surface? I finished my AOWD class this weekend and on the 3 dives we made deep (74', 78' and 83', I was pretty low on air when I got to the surface. I was curious as to know what others have. My computer is set to alarm at 600psi, but on all 3 dives I was under that when I started my ascent, and quite a bit below that by the time I got to the surface (and only 1 did I do a safety stop, and even then it was only a minute long (it wasnt a REQUIRED safety stop). My instructor should have been more aggresive on going up when I told him I had 800psi left.. he just gave me the ok sign and we kept diving, (while I kept watching my gauge).

 

[Kayla]

always try to surface with 500 PSI in my tank, just to be on the safe side, I figure, better safe then sorry!


Kayla

 

[Sebastian]

By "end your dive" do you mean turn around and swim back to the entry point or surface?

Whenever I go diving we always agree before the dive to turn around when we have like 110 bar (1595 PSI) left.

I never had to surface because of being low on air. I had like 2 situations where I was low on air but my buddy always had enough air left so he gave me his octopus and we dived back to the entry point.

I usually have 50-60 bar (725 - 870 PSI) left when I surface.

 

[theslyfox01]

I start to come up on 50 BAR, unless in really shallow water, and aim to have 30 BAR for the surface in case theres chop and brreathing off the reg is easier than the snorkel

 

[Walter]

It's going to depend on your depth, your air consumption and what tanks you are using.

The ideal is to begin your ascent with enough air to ascend slowly, to make safety stops (I plan in deep stops) and to reach the boat (shore) with enough air to deal with unexpected emergencies.

Your instructor was wrong to continue the dive, but so were you. You can give the signal to surface. When you feel you need to be ending the dive, you need to give that signal and then end the dive.

 

[Diversauras]

ditto on Walter's comment.

 

[The Chairman]

When to turn your dive is a tricky issue as it depends on the depth/conditions etc, etc. In the spring, I allow my students to get down to 500 psi. Sure we culd take it lower and still be safe (24 ft max) but what am I teaching my students by doing this? Nothing that I want them to learn. In the open ocean on a boat dive, we ascend when one of them hits 800 psi... and we do a 5 minute safety stop. Now how much do we actually need to surface with??? It really doesn't matter now does it? DO YOUR SAFETY STOP as long as you have air to breathe. Now, I don't mean do a 45 min safety stop cause you got air... three to five minutes is just fine. I mean that your safety stop is FAR MORE IMPORTANT than surfacing with an arbitrary amount of air (like 500 psi). Lets face it... you don't get any credit for the air you didn't breathe, and you will feel FAR BETTER for breathing some of that air at fifteen feet for three to five minutes.

I have dove with too many divers that "freak" when their guages read 500 psi and surface 'cause they just gotta surface with 500 psi. They missed the point. You can plan to surface to surface with 500 psi... but don't blow your safety stop to fulfill your plan. You don't need to play "catch up" with your air! If you came up with less than you wanted to, then plan your next dive a little bit better. Watch your guages a bit more closely the next time you descend, but DON'T SACRIFICE YOUR SAFETY STOP! They are not really optional, UNLESS there is an emergency like you have NO air or there is a great white circling around you.

As for your instructor... not sure what they were thinking or how safety conscious they are, BUT... It's your dive and your life. Next time you give the "Low on air" signal, follow it with an "I'm ascending" signal and then start your ascent. If they are any good as an instructor, they will ascend with you. Of course, a great instructor would be giving you the thumbs up before you even realise that you only have 800 psi. Just don't get into the habit of doing "trust me" dives with anyone... when you feel uncomfortable with the situation (low air, unfamiliar territory, etc) call the dive. That's your right to do. You don't even have to explain yourself either... just give the thumbs up and follow YOUR plan.

 

[Diversauras]

I don't know how to make it work, but Pete's comment needs one of those high Mass singing Amens.... maybe that is Aaaaaahhhhhhhmennnnnnnn

 

[MikeFerrara]

NetDoc once bubbled...
Of course, a great instructor would be giving you the thumbs up before you even realise that you only have 800 psi.

And of course the student would need more work until they were able to track their own gas usage.

 

[roakey]

Kayla once bubbled...
always try to surface with 500 PSI in my tank...

I always found the statements "Surface with 500 psi" or "Get on the boat with 500 psi" amusing.

This is like the driving directions I was once given: "Turn right a mile before the big red barn."

Telling someone what they should end up with is not the least bit helpful. Telling them how to figure out when to end the dive while at the bottom is the tool they really need.

For this tool, search the board for "Rock Bottom" -- I think UP had a discussion on it awhile back.

Roak