Almost out of air after descending against a strong current

[dorkito]

The Situation
The descent was down an anchor line to a wreck. The current was strong, estimated about 1.5 knots near the surface. The anchor line was close to horizontal. It was hand over hand all the way down. It was a good distance and slow going. I was last in a group of 4 (two buddy pairs) plus our guide (a highly experienced instructor). It was our group's 5th dive together over 2 days. My wife was my buddy. I was relaxed and calm. No fighting the current, no finning, just gentle breathing. I was "flying" above the line, nearly horizontal, but slightly head down. It was fun with the exception of the layer of jellies that we descended through. That required some bobbing and weaving, but a few stings on the face were inevitable. We got to the end of the rope (depth about 18 meters), swam off of the line into the current for a short burst, then sheltered behind part of the wreck for a couple of seconds. We then did a quick hop over over the wall onto a protected space that was big enough for the whole group. I checked my pressure gauge and did a double take. It was down from 200 to 50 bar! WTF?!?

I signaled to my buddy and she was shocked. I made it clear we were going to ascend immediately. Our pre-dive plan was to return to the anchor line with at least 70 bar left, so we were on the same page. She darted forward and got the guide's attention. I was already turning back towards the rope. The guide quickly came over and checked my gauge for himself. I wasn't panicking, but my heart was THUMPING. We made our way to the anchor line. I started to move up in a deliberate fashion, and the the guide told me to stop. Ten seconds later, he had made sure the other team was in control, and he came up to me and offered his primary, and he took his integrated alternate. I was surprised that he wanted to do that, since I still was thinking I would just simply ascend. But it seemed prudent, so we began sharing air and away we went. Once I found a comfortable position it was a relaxed, controlled ascent up the anchor line. Mercifully, the jellyfish layer was mostly gone. Just below the surface I swapped to my primary, surfaced and inflated my BCD without issue. Got to the boat and had an interesting conversation with my wife and the guide.

I suspected that something was wrong with my gear, but everything looked just as it did during my pre-dive safety check. I checked my pressure when I did my first check, my buddy checked it, I double checked on the inflatable boat that took us to the anchor line off of the bow, and my guide had each of us check and report to him before we entered the water. So I'm sure I started with a full tank. The guide is convinced that my alternate went into free flow while I was pulling myself against the current. He's seen it before at this very site. There wouldn't have been anyone behind me to notice, and the current would have swept the bubbles away from me before I could have seen them. It could even have happened when I was distracted by the jellies.

Lessons Learned (so far)

• Check your gauges often, no matter what. I was focusing on the descent and was convinced everything was just dandy, so I didn't feel an urgency to do it. I also didn't want to fall behind the group. Regardless I should have made a point to check. It's good that I did check when I got off the line, though. It was on my mind, and I did it as soon as we were in a safe place. If I hadn't done that I might not be writing this [shuddering]. I'm considering getting getting air integration with my dive computer to give some redundancy and to make it easier to check more frequently.
• Currents pose special risks. I wasn't aware that an alternate could free flow from the pressure that the current puts on it. If I had been aware that it was a possibility, I would have checked on it frequently to make sure the purge valve wasn't facing straight forward. I would also have been more likely to notice a funny sound.
• When critically low on air you should begin sharing air immediately. Don't wait until you are out of air. Sharing air immediately gives you the ability to deal with a contingency that causes you to separate later for some reason.
• My buddy made the right choice to get the guide's attention. Otherwise we would have just ascended up the anchor line, and I would likely have run out of air, since I was running through it faster than I thought. (I was surprised to hear that I was already at 20 bar when I started sharing air with the guide). We have practiced sharing air before, but what if her back was turned or something was distracting her just as I ran out of air? I could easily have panicked, and we all know how that story ends [shuddering].
• If my wife hadn't been able to get the guide's attention right away, we should have ascended immediately instead of heading for the anchor line. Share air, grasp arms and go up slowly. No safety stop. Despite the current, deploy the SMB at the surface, not at depth, in order to avoid additional extra task loading while sharing air. I'm confident that the experienced and competent boat crew would have seen us at the surface with the SMB inflated, even after drifting.

[FONT=verdana,sans-serif] [/FONT]
[FONT=verdana,sans-serif]I hope this helps others avoid this situation or deal with something similar in the future. I look forward to learning more from the comments.[/FONT]
[FONT=verdana,sans-serif] [/FONT]
[FONT=verdana,sans-serif]BTW, we dove the same site again in a few hours. Great dive![/FONT]

 

[keller34]

I keep my octo near my shoulder on a breakaway. If it does free flow, and it does every once in a while because of the way I have it tuned, I will know right away. Do you let yours dangle or clipped at your waist?

 

[dorkito]

My alternate is on a magnetic clip that attaches to a D ring in front of my right shoulder. One magnet on the hose, one on the D ring. So the alternate is near the center of my chest. I little below and to the right though.


Sent from my iPad using Tapatalk HD

 

[kelemvor]

A necklaced secondary or an air integrated computer could help with that a little bit. The necklace because you're going to be more likely to notice a tankful of bubbles hitting you.

Air integrated computers (at least mine does) have a few warnings/beeps they can throw for various configurable tank pressures. I have my galileo beep when I get to about 100 bar, and again when it gets to about 55 bar.

 

[TSandM]

Sounds like a very nicely handled situation. I have had my backup reg freeflow when scootering (which is essentially the same as moving into a strong current). I use a bungied backup, which is right under my chin, but the speed with which the bubbles were blown away along my body caused me not to notice the freeflow. I have since learned to detune the backup reg when scootering, to help prevent this. (You can do this by putting a reg in "pre-dive" setting, or by detuning it if you have an adjustment for breathing effort.)

I think the strongest lesson here is that you are better off sharing gas BEFORE you are out, than waiting until that moment to begin. As you realized, maintaining all the gas reserve you can on your own back gives you options if you get separated, or on the surface while trying to get back to the boat.

The only other comment is that, if you are afraid that you and your wife can't execute an air-sharing ascent solidly, you just need to practice it more.

 

[Doppler]

Glad you managed to make it back up to chat about it.

Plenty of decent advice already.

Now, I will stop patting you on the back and telling you **** you already know.

The lesson to be learned is situational awareness, regardless of whether the issue was a free-flowing second stage or a dive factor through the roof because of the workload. A couple of SA questions for you... did you check during your descent to see if any of your buddies were working hard and stressed (rate of breathing), and -- more importantly perhaps -- did you look to see if any of them was bleeding gas on the way down?

Obviously, your buddy was not paying attention to your kit... the thing to learn here is not really directly covered in anything you've mentioned. You and your buddy have to have each other's back. That gas that disappeared, actually belonged to your buddy. What if she too had suffered gas loss on the way down. Not unrealistic in those conditions. As you know, people die because they do not pay attention. Enlightened self-interest if nothing else should alert you to an issue with her kit... as well as yours... and vice-versa.


P.S. was the dive guide the last one down the line?

For reasons already mentioned and others, they should have been and THEY should have noticed the rottweilers circling around your kit. I would not be praising them quite so loudly if I were you. It does not seem to me that they did a very good job.

Of course, I'm critical of sloppy dive techniques because I cannot breath water.

 

[nimoh]

some other lessons learned:

- look at your buddy once in a while during descent, even if they are behind you.
- practice deploying an smb from depth in case the situation arises again.

 

[phoenix31tt]

I was just about to make the point Doppler made...
How could such a free flow go un-noticed by your buddy? I notice the tiniest stream of bubbles from my buddy's rig and we dive in strong currents alot...

Its always a possibility as well that you could've been breathing that quickly without noticing, being so excited with the descent etc...

Handled well after the fact and good takeaways as well

Sent from my Nokia Lumia 920

 

[danvolker]

And dont use diveboats that anchor on high current wrecks...if this captain was any good, and the wreck was going to be dived with a big current, it should have been a drift drop from well upcurrent.

 

[TSandM]

I sort of assumed this diver was the last one going down the line. It is definitely the case that, if that was NOT true, somebody else should have noticed the gas loss. In the case of my scootering event, my buddies alerted me to the problem before much gas was gone.