Equipment A Dive to Remember: Overcoming Technical Hurdles with Teamwork

[Njord fr]

Two weeks ago, I dove with two instructors from my club, making it a group of three, to do some exercises on assisted ascents, deploying SMB, navigation, etc. It was my first time diving with my newly acquired second-hand POSEIDON regulators that had just been serviced by a specialist. I was so happy. I was using a primary first stage with a JetStream and a secondary first stage with a Cyclon 5000, along with the direct system and SPG.

We were in a quarry, where the water was 8 degrees Celsius at -20 meters. Everything went smoothly at first; the exercises were successful, and the initial dive was completely fine.

Towards the end of our second dive in the afternoon, I told my instructor that I was starting to feel cold in my 7/8mm Apeks wetsuit. He moved us closer to the surface while we continued exploring. Checking my SPG, I saw I was down to 100 bars (1400psi). I thought it was a pity; had I not been cold, we could have stayed longer at -20 meters.

When we reached -7 meters, one of the instructors asked me to deploy my SMB as an exercise. I placed my Cyclon 5000 in the SMB's mouth and pressed the purge button, but then the Cyclon went into free flow, sending me up a few meters in a storm of bubbles, blinding me. I felt one of my instructors grab the tip of my fin to prevent me from surfacing. They struggled to bring me back down to the bottom. I felt a hand groping over me to find my purge valve and felt my BCD deflating. The Cyclon was still in free flow, and one instructor had to manipulate it until he could shut off the Cyclon's valve.

I was still breathing from the JetStream because my tank has two valves, and thankfully, I was. Checking my SPG again, I was down to 30 bars (400psi). I signaled to my instructors that I was on reserve and finished the dive breathing from one of their octopuses.

All's well that ends well, and they commended me for staying calm. One instructor mentioned, "This kind of problem at 7 meters is manageable, but at 40 meters, it's unforgiving." I know the issue was technical and beyond my control, but I still can't help feeling a bit guilty, even though I can't explain why...

 

[grantmac]

Sounds like you need to familiarize yourself with your new regs and possibly have them rechecked for adjustment post-service.

 

[Landau]

A free flow, even with a cloud of bubbles, should not cause you to rise up. The more air bubbles rising around you the less water their is to provide buoyancy. In an extreme case, this could cause you to sink instead of rise. The rise was most likely caused by tunnel vision, only thinking about the free flow instead of buoyancy and maintaining depth.

You can try this test in a pool - have your buddy (or multiple buddies) purge their alternates underneath you to see if they can make you float up. I'd wager they can't

 

[Rilelen]

I think (not entirely sure) the issue was that the free flow occurred while inflating the SMB, which added too much air to the DSMB, which in turn pulled the OP up towards the surface in what would have resulted in a rapidly accelerating ascent had his instructors not stopped him.

 

[inquis]

I think (not entirely sure) the issue was that the free flow occurred while inflating the SMB, which added too much air to the DSMB

Most people are positively buoyant when deploying the DSMB via regulator purge, so there's only a very short window to release. The mistake (assuming I understand the events correctly) was not letting the DSMB go when the freeflow occurred. While one hand holds the unrolling spool, the other can try to stop the free flowing reg, turning it over or smacking it on a knee if the purge button were stuck. Ideally, the buddy would have taken the spool while OP tried to terminate the freeflow. Everyone is neutral throughout.

OP, if the above assumption is accurate, you might develop a technique that leaves you neutral before release. Interestingly, I've had someone ascend past me, mid-deployment, and if I were unable to delay release, they easily could have been entangled. As it was, I just moved over a bit (sighing inwardly) and then let it go. No drama since I was in control of the release timing.

 

[stretchthepenn]

A free flow, even with a cloud of bubbles, should not cause you to rise up. The more air bubbles rising around you the less water their is to provide buoyancy. In an extreme case, this could cause you to sink instead of rise. The rise was most likely caused by tunnel vision, only thinking about the free flow instead of buoyancy and maintaining depth.

You can try this test in a pool - have your buddy (or multiple buddies) purge their alternates underneath you to see if they can make you float up. I'd wager they can't

If you put the bubbles beneath the diver, then maybe what you're saying is accurate. But if you put the bubble storm at the diver's same level or above the diver, that bubble storm creates an upwelling that can take the diver along for a ride.

Much the same thing happened to me while simulating a deco stop. I exhaled, my hose popped off the second stage and created a whiteout, and I started rising fast.

 

[crofrog]

I know the issue was technical and beyond my control, but I still can't help feeling a bit guilty, even though I can't explain why...

This a procedural and equipment issue, but the issue isn’t that the reg free flowed the issue is that you used the reg in such a way as to provoke a free flow.

This is another example of why purging a reg into an open bottom smb is not risk appropriate.

Orally inflate or use a no lock connector

 

[Njord fr]

Most people are positively buoyant when deploying the DSMB via regulator purge, so there's only a very short window to release. The mistake (assuming I understand the events correctly) was not letting the DSMB go when the freeflow occurred. While one hand holds the unrolling spool, the other can try to stop the free flowing reg, turning it over or smacking it on a knee if the purge button were stuck. Ideally, the buddy would have taken the spool while OP tried to terminate the freeflow. Everyone is neutral throughout.

OP, if the above assumption is accurate, you might develop a technique that leaves you neutral before release. Interestingly, I've had someone ascend past me, mid-deployment, and if I were unable to delay release, they easily could have been entangled. As it was, I just moved over a bit (sighing inwardly) and then let it go. No drama since I was in control of the release timing.

I think what you say is right, I did not let the DSMB go, I was sticking to it and one of my instructor took it off my hand.
I am learning, and I guess I have a buyancy problem while inflating my DSMB because I go up a little every time. I guess I have to be negative before inflating it to compensate right ?

 

[Searcaigh]

@Njord fr

Were you diving dry or wet?

 

[inquis]

I guess I have to be negative before inflating it to compensate right ?

No, because if you delay adding air then you will drop, which is also undesirable.

One of the easiest ways to stay neutral throughout during deployment is oral inflation, because part of your buoyancy just shifts from your lungs to the DSMB but doesn't change in overall amount. Dumping a little from the wing and compensating with lungs beforehand (and after release until you blip the inflator with your non-spool hand) will enable a larger fill. Your instructor friends should be able to elaborate/demonstrate.

You can achieve a similar thing with regulator-based inflation by exhaling while purging, but timing and amount added are variables to work out.