Ran out of air today...

[D_B]

I think that Lead Turn and TSandM make some good points.
When your on your unrequired safety stop, or at 15ft under the boat, with 700 or 800psi ... what is another few 100psi ?

While I'm pretty sure that I check that my gage is 0 before turning on air I don't think I've ever turned my air off after checking tank pressure and checked my gage for 0 then.

(mind you, this is coming from someone that while well trained (and uses Lamont's Rock Bottom Calculations ) .. does not have many dives

 

[WarmWaterDiver]

Ah, my misunderstanding - I'd incorrectly figured you were using some rental gear in conjunction with the Intro to Tech training. Maybe it's just another case in point to have all your own gear for any dive you plan to perform if possible.

 

[DandyDon]

Glad yours went so well. OOA is a sucky feeling, but you were in great position and you have a good head - minor challenge.

 

[DA Aquamaster]

The "back on the boat with 500 psi remaining" thing is fine as long as people don't get so obsessed with getting back on the boat with 500 psi, that they forget why you want 500 psi at the end of a dive in the first place - to ensure you have the gas to extend a safety/deco stop at the end of the dive. Or even for minor things like waiting at 20 ft and extending your safety stop while the crowd around the ladder clears, since it makes a lot more sense to spend the time at 20 ft rather than floating on the trail line.

The 500 psi reserve does you absolutely no good if it remains in your tank when you should have used it to add some needed safety factor to the end of the dive.

 

[Jim Lapenta]

Many also are not taught that if they want you back with 500 psi on the boat then you do not have 3000psi to work with assuming that is the fill. You have 2500 psi to plan your dive with if new or being conservative. If the boat wants 500 left in the tank and you are diving 1/3rds then you will divide 2500 by 3 and use that. Result is plenty of gas when back at the line to play around or do a nice leisurely ascent and safety stop.

 

[Ayisha]

I was taught to look at the gauge to confirm it reads zero and then turn it away from you (no longer neccesary as new SPG's don't decontruct the way the old ones did if they fail), pressurize it and then look and confirm that the tank reads full as expected.

I was not taught to do this, but I wonder if this is the procedure that I should be teaching to my students. Based on reading this thread, this sounds like a good idea.

A couple of months ago on a boat in Roatan, I heard a diver across the boat tell his buddy and those around him that his gauge was showing a drop of 100 psi. He was very concerned because his air consumption is very high and he was checking for a leak or reason. He was fiddling with his gear for a while. Well, shortly after, I had backrolled in on the other side of the boat and then heard thrashing and yelling on his side of the boat. I found out later that he had jumped in with the air off, thinking that it was on because it still showed a pressure of 2900 or so. His buddy turned it on for him. Everyone on the boat (including me) had assumed that with all his concern and checking his gear, that he had checked to make sure the air was on. He had not purged the air, however, between setting up the tank and arriving at the dive site, so it still showed a nearly full tank. That had confused him into thinking his air was on. Purging it after setting it up would have avoided that confusion. Inhaling while watching the pressure reading would also have signalled that the air was off, since it would have fluctuated with a closed valve and a pressurized reg.

 

[LeadTurn_SD]

A couple of months ago on a boat in Roatan, I heard a diver across the boat tell his buddy and those around him that his gauge was showing a drop of 100 psi. He was very concerned because his air consumption is very high and he was checking for a leak or reason. He was fiddling with his gear for a while. Well, shortly after, I had backrolled in on the other side of the boat and then heard thrashing and yelling on his side of the boat. I found out later that he had jumped in with the air off, thinking that it was on because it still showed a pressure of 2900 or so. His buddy turned it on for him. Everyone on the boat (including me) had assumed that with all his concern and checking his gear, that he had checked to make sure the air was on. He had not purged the air, however, between setting up the tank and arriving at the dive site, so it still showed a nearly full tank. That had confused him into thinking his air was on. Purging it after setting it up would have avoided that confusion. Inhaling while watching the pressure reading would also have signalled that the air was off, since it would have fluctuated with a closed valve and a pressurized reg.

You are right: The pressure reading would fluctuate with a partially-open valve.

But Fully-Closed with a pressurized reg you'd see a steady pressure drop with each breath.... for most people you'll get 2 breaths then nothing at all.

I know of several cases of divers entering the water with "almost closed" tank valves. Sometimes self-inflicted, sometimes inflicted by a helpful boat crew... usually caused by turning the valve the wrong way then cracking it 1/4 turn. The reg will provide enough air at the surface, but get down to 60 feet or so and the diver feels like they are breathing through a straw.

Like many divers, I was taught to open the valve all the way, then close it 1/4 turn. This was done, in theory at least, to prevent a valve from "sticking" in the open position. I don't know if this was a carry-over from the earliest tank valves, or from non-scuba applications (we used to do this with ship valves).

I no longer do this.

I want my tank valve full-open or full-closed. Nothing in between. When I do a buddy check, I check for a "hard stop" on their valve to ensure full-open position, and have them do the same with mine. This way the valve is either fully open or, if lightning struck and I forgot "Righty Tighty - Lefty Loosey", the valve is fully closed.

Then I take a few breaths on the reg before entering the water. If the valve is closed, I'll know it instantly without looking at the gauge, and will "fix" it before entering the water

Best wishes.

 

[DandyDon]

Like many divers, I was taught to open the valve all the way, then close it 1/4 turn. This was done, in theory at least, to prevent a valve from "sticking" in the open position. I don't know if this was a carry-over from the earliest tank valves, or from non-scuba applications (we used to do this with ship valves).

Yep, but all of the agencies have deleted this haven't they? Just waiting for old instructors to stop teaching it...

I

want my tank valve full-open or full-closed. Nothing in between. When I do a buddy check, I check for a "hard stop" on their valve to ensure full-open position, and have them do the same with mine. This way the valve is either fully open or, if lightning struck and I forgot "Righty Tighty - Lefty Loosey", the valve is fully closed.

Yep, my home bud and I do this on the boat and at 15 ft descent stop. He closed it once on the boat, but better than barely open.

Last month, without my home bud, a Coz skipper left mine at 1/4 open and I couldn't get below 40 ft until I switched to my pony - then caught up to the group and got a lady to open it for me. I have new plans for maybe reaching it myself which I have not been able to do; need some practice dives.

 

[Thalassamania]

Many also are not taught that if they want you back with 500 psi on the boat then you do not have 3000psi to work with assuming that is the fill. You have 2500 psi to plan your dive with if new or being conservative. If the boat wants 500 left in the tank and you are diving 1/3rds then you will divide 2500 by 3 and use that. Result is plenty of gas when back at the line to play around or do a nice leisurely ascent and safety stop.

Jiim,

I'm not sure that makes sense. Let's assume a rule of thirds for the dive, that means 1,000 out, 1,000 back, 1,000 for my buddy (if something goes wrong). With your scheme you're planning to have 500 extra, even if something oes wrong, I just can't see that. I have no problem with a gas management plan that puts aside more than a third. Lord knows, you'd be hard pressed in some situations to make it back turning at 2,000 psi if your buddy has a failure at the extreme end, but to plan 1,000 for an emerency and to keep 500 PSI so that the boat Captain or DM is happy seems to me to be a bit limiting without much of a return. If there is a real problem they should not have any problem with you using up your reserve gas.

 

[LeadTurn_SD]

Yep, but all of the agencies have deleted this haven't they? Just waiting for old instructors to stop teaching it...


Yep, my home bud and I do this on the boat and at 15 ft descent stop. He closed it once on the boat, but better than barely open.

Last month, without my home bud, a Coz skipper left mine at 1/4 open and I couldn't get below 40 ft until I switched to my pony - then caught up to the group and got a lady to open it for me. I have new plans for maybe reaching it myself which I have not been able to do; need some practice dives.

Thanks for sharing that Don! Scary.... and kudos on the calm reaction!

It does happen. It seems more common on resort dive boats (I think, in their defense, the boat crews are rushing to switch tanks, chatting with guests, what have you, and just simply goof).

But I do know of a self-inflicted case on a guided shore dive here in Hilo: The diver had set up his own equipment, turned on the air and backed-off 1/4 turned like he always did, listened to the dive briefing, then went to put his tank on and forgot he had already turned on the air and turned it off and back 1/4 turn, and thus entered the water with an almost-closed valve.

His experience once he got to around 40-50 feet was just like you described, but unlike you he did not remain calm and bolted for the surface because he assumed he had suffered a catastrophic regulator failure.

Regarding reaching the tank valve: I think a lot of folks with single-tank rigs have difficulty reaching the tank valve. Sometimes it is restricted shoulder mobility, but often it is just that the tank rides too low to reach the valve.

It is a very good thing to check (to see if you can can reach the valve) in a non-emergency situation, both on the surface and underwater. If you can't reach it "normally", most folks find they can reach it by getting horizontal, and loosening the waist strap / cummerbund or whatever setup your particular rig has. Once loosened, you should be able to pull UP on the shoulder straps and slide the tank up your back, then reach the valve. It is good to practice this so that you know you can get to the valve quickly if needed.

Best wishes.