How do divers not realize their air isn't on?

[Saltyhawg]

Our instructor did air off under water in the shallow (~3ft) end of the pool. We knew what was going to happen. She wanted us to find out what it felt like and what it looked like on our SPG. She quickly turned it back on after we gave the OOA signal. We also practiced reaching back and turning it on on the edge of the pool.

My rig has one breath, two at most with air off. I always pre-breath both regs...twice if it's a negative entry.

 

[Snoweman]

Breathe deep and fast while watching your pressure gauge. If it even twitches something is wrong.

OK..., this was one post that may have helped a young couple on a dive boat I was solo (paired with the DM). He turned on his air, took breaths and went over. He was fine until about 90', and then the air was very low. I think he said he check his gauge and then took his wife's octo. They did a controlled ascent and abandoned the dive. After getting on board, he realized his error. The captain or mate had already turned on the air. He had turned it off, and then turned it back a quarter turn. That gave him air for a while, but soon gave out.

One fallacy was turning it a quarter to half turn back. That is no longer needed. I'm not sure the quick breaths would have seen a twitch in the needle, but it might have. I just remember him being bummed he blew a dive due to a forced error.

For me, I'm such an air hog, I preserve every bit of air I can, and orally inflate my BCD before entry. I've never done a negative entry, and I'm not sure I really want to. Seems like a risk that can be avoided with other means (unless you're in the military, on a mission).

 

[TMHeimer]

I rarely do a charter (MAYBE once yearly) or a deep shore dive to say 80+ feet (always with a buddy deep). So, as with other procedures on a boat, I have to be very sure that I do everything right, and air/gas being on is # 1 of importance.

On my usual shallow shore dives I probably have forgotten to turn the air on 4-5 times over the years. As these are almost always solo with me being the only person around, it is odd that I think in all cases I had someone around who could turn on the air.
I turn on air gearing up right before donning the unit. Got in that habit years ago when I had my reg hooked up and air on, driving to the site, threw on the breaks and somehow resulted in the 2nd stage purge being pushed in. Since then I don't even hook up the reg until at the site.

 

[The Chairman]

You don't always want to put air into your BC. Many of the drift entries in SE Florida are quick, negative entry dives. Simply pre-breathe your reg to check if your cylinder is on.

I agree with Craig here. I rarely have any air in my BC. However, I am just a tad negative at the beginning of the dive that I could swim up should there be an issue. Overweighting can kill.

 

[Kharon]

I dive almost exclusively from shore. If I turn my air on the transmitter starts searching for a paired computer, which isn't on till I splash. In order to save battery (I know, dumb) I try to turn on the air just before I walk in. Sometimes I forget, but it's no problem because I'm standing in waist deep water and at worst have to drop my BC to get at the valve.

That's why I jumped at the slob knob that was sold on SB a while back. Now I have the valve knob right on my chest. I can wait to turn it on till right before I put the reg in my mouth pre splash. And the knob on my chest reminds me that there's one more thing to do.

 

[Vicko]

When DM-ing I usually check all the tanks leaving the boat, then i toss mine overboard, make sure everyone is fine, put it on, and approximately at that point realize i forgot something.
It happens every now and again, it's embarrassing and not a big deal as it takes me about half a second to crack open the valve.

I saw a diver do the same thing in doubles with 3 stages, he did not open his backmount tanks or his argon bottle, his dry suit basically vacuum sealed him but luckily he was using his travel stage when he jumped, i think he managed to open his tanks when he fell past 40 meters, and he had some really really bad bruising along his torso.

 

[Saltyhawg]

I agree with Craig here. I rarely have any air in my BC. However, I am just a tad negative at the beginning of the dive that I could swim up should there be an issue. Overweighting can kill.

Agree completely. With zero air in my BC I still have to exhale significantly to descend. I would have zero problems swimming my rig to the surface if needed.

Is it not possible to reach back and turn your air on? Are there some setups that make this impossible?

I don't think there is anything wrong with negative entries. There are some sites that are almost impossible to dive as a group without them. Do your due diligence before you splash, splash with your buddy and there is nothing to fear.

 

[aquacat8]

I bet those old guys that learned with J valves know what OOA feels like and would not panic... until they reach back today and oh oh no rod to pull! I am thinking of trying to locate a J valve for mucking around in our local black water. If I even have the courage to do that. You can't even read your spg.

 

[The Chairman]

Is it not possible to reach back and turn your air on? Are there some setups that make this impossible?

I can barely handle this with doubles, but my arthritis keeps me from doing this with singles. Half of my tanks have 'wrong sided' valves which makes the issue twice as hard. Which side is the valve on?

 

[aquacat8]

This is where doff/don exercises, which some think are unnecessary, could be handy with a single tank rig: slip out of one side, hold on tight, especially if weight integrated, fiddle with valve, if it doesn't work let go and CESA.