Two Dives, Two near Emergencies, Lessons Learned

[aquaregia]

I should have skipped the first dive, and I definitely should have ended the dive early when I had so much trouble with breathing and buoyancy. I will definitely take heed of your advise to do an easier dive the next time I go somewhere unfamiliar. I could only get in 4 dives on this business trip, so I didn't want to skip the first one.

Historically I've been very bad about calling dives when I'm not having fun, but usually there's a reason I'm not having fun and it can easily be the start of the incident pit. I've recently gotten much better about things like this.

He had just had his second stage serviced at the manufacturer, so it was really strange that it was leaking water.

I wouldn't take a reg on a serious dive that I hadn't dove in benign conditions at least a few times since the last service. Taking stuff apart and putting it back together always introduces a possibility for mistakes.

...instead ended up trying to share my primary. If that is what comes natural to me, I ought to practise it that way, and maybe get a bungeed octo necklass.

I think primary donate makes sense for a lot of reasons. Regardless of whether you use a necklace (I do and I love it), make sure you know where your other second is before you give yours away.

 

[MXGratefulDiver]

windapp ... I just want to say that I'm pleased to see someone at your experience level putting this much thought into learning from your mistakes ... and in particular the dive planning and gas management comments.

Kudos ... I'd say you didn't really do anything "wrong" ... you made mistakes, just like we all do. The key thing is to understand why, so you can avoid making them again ...

... Bob (Grateful Diver)

 

[norcal_diver]

At 1100 PSI (just over 70 bar - my gauge is imperial), I signalled time for me to ascend. My buddy, and the divemaster, ascended with me. We did a deep stop (required by the divemaster's computer), and at 1:30 into the safety stop, my tank went below the IP.

I think you handled the situation pretty well for having 0-24 dives. What I concerned is your equipments.

At 1100psi you called the dive. Assumeing you are at max depth, 29m (say 100ft), you ascent to 50ft for deep stop at 30ft/min rate. That will take ~2 minutes, then 1:30min at deep stop (50ft). Total time from ascent (1100psi) is 3.5 min, then tank pressure went below IP (150psi). It is very unlikely you can cosume that much air in such a short time. I am thinking your SPG was reading the properly pressure at all. Just a thought.

 

[windapp]

You may be right. At a minimum, I will get a tank full of air, hook up an alternate SPG to the other HP port, and compare the gauges over the range to ensure that my SPG is reading properly.

 

[JIsgren]

Quick question, what did your SPG read when you surfaced on the first dive? Another possibility is that you valve was only partially open. As you breath the air from the HP tank can't make it into the hose fast enough and the pressure in the hose drops. Initially with the tank at a higher pressure the hose pressure did not drop below the IP, later at a lower pressure the drop in the hose fell below the IP.


You can sometimes see this if you watch you SPG as you take a breath and see the needle dip.