Scary experience - Any thoughts?

Hi All.! New to the forum so apologies if this is in the wrong place.

Have been reading a lot of stuff on the net and this seems the place to ask as there’s a lot of knowledgeable people here.

I wanted to ask about an incident that happened to me last month whilst out diving in the Caribbean.

I’m a holiday diver, no huge experience, just 2 or so dives a year maybe less, got my certification in 2000 but did my first dive at the age of 10 in the early 70s. So basically not experienced but comfortable underwater.

I was on the first of a 2 tank boat dive with my newly (half) certified daughter (12). I hadn’t done a dive in about 6 months and it was all the dive shops equipment so I wasn’t familiar with it. (apart from my own computer, fins, mask)

We had completed the dive, got down to 1000psi on both our gauges (my daughter slightly less, maybe 900) and were coming up. Was starting a safety stop at about 3.5/3m (13 feet) I went for a breath and nothing. Felt like breathing through a tube with someone holding their thumb on the end, just the tinyest squeak of air. A blockage I thought and as I do a lot of snorkelling it felt natural to blow out to try and clear (a mistake I should think). No change. Right I thought I’m out of air, something wrong with the regulator let go to the back-up regulator. So changed air supply and exactly the same thing happened.

My buddy/daughter was about 3 or 4 feet below me and I was really out of breath so I panicked slightly and thought 4 feet down or 12 feet emergency ascent. I opted for the latter (remembering to breath out). Once on the surface I was a bit shaken, but I’m sure there was air in the tank to inflate my BCD with no problem and the gauge still read 1000psi. We hadn’t been down long enough for me to use the full 3000psi I started with; only 35mins.

OK no great shakes coming up from 12 feet but the problem is what would have happened further down. In hindsight and with the experience I would have got closer to my buddy as soon as I had a problem but things happen fast.

Anyone have any idea what might have gone wrong, I’ve no problem if someone says I was at fault. I just want to learn how to prevent/recognise this in future?

What was your SPG showing when you surfaced? Perhaps it was faulty, or debris in the tank was blocking the dip tube.

Despite you saying there was enough gas to inflate the BC at the surface, I suspect a faulty SPG and an empty tank for several reasons. It doesn't take much gas to inflate the BC, the flow through a BC hose is much less than through a LP hose, and on the surface there would be more gas available than at depth (even 10 feet). So those 3 factors could explain how you were able to inflate the BC enough at the surface. But with both second stages failing to provide enough gas, it sounds like an empty tank. Remember the tank isn't actually empty, just insufficient pressure to overcome ambient pressure. Also, most 12 year old girls hardly use any gas at all if they are comfortable in the water, even newly minted divers. Their RMV is virtually nonexistent. So the fact that she used the same amount or more than you did is also suspect.

Your decision to ascend instead of going to your buddy might not have been the wisest. Yes, you were near the surface, but you did leave your inexperienced daughter down below, probably freaked out a bit. As for avoiding it in the future, that's why some folks carry a pony bottle. An alternate air supply is better than an alternate air source (octo). And using your own gear is usually better than rental stuff.


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SPG was still showing 1000psi but I inflated my BCD when I got to the surface so wondering how that worked if the regulators didnt. Are they on a seperate pressure system?

---------- Post added April 29th, 2014 at 07:04 AM ----------

kwinter:

Despite you saying there was enough gas to inflate the BC at the surface, I suspect a faulty SPG and an empty tank for several reasons. It doesn't take much gas to inflate the BC, the flow through a BC hose is much less than through a LP hose, and on the surface there would be more gas available than at depth (even 10 feet). So those 3 factors could explain how you were able to inflate the BC enough at the surface. But with both second stages failing to provide enough gas, it sounds like an empty tank. Remember the tank isn't actually empty, just insufficient pressure to overcome ambient pressure. Also, most 12 year old girls hardly use any gas at all if they are comfortable in the water, even newly minted divers. Their RMV is virtually nonexistent. So the fact that she used the same amount or more than you did is also suspect.

Your decision to ascend instead of going to your buddy might not have been the wisest. Yes, you were near the surface, but you did leave your inexperienced daughter down below, probably freaked out a bit. As for avoiding it in the future, that's why some folks carry a pony bottle. An alternate air supply is better than an alternate air source (octo). And using your own gear is usually better than rental stuff.


Thanks for the reply - all good points. And I do like the idea of a pony bottle, will look into that infuture. As to the air used; I did 4 other dives after this - all longer than this one and all coming up with 700 - 900psi about the same as my daughter.

BTW she was a little freaked but did the next 4 dives with me and still loves it!

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What equipment was changed between this and the other dives? Just tanks or the rest of the equipment?

Could have been a problem with the first stage.

First I would like to said glad all came out well for you both. Next I would say I would not have dove with same equipment after that till I or some one check said equipment . .Maybe ask a fellow diver / daughter to put there 1st/2nd stage on your suspect tank and verify.(all so some may have a tank gauge to check pressure)Until then I would call my dives ,There is always another day to dive

Sounds like your valve may have been only cracked open

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AlfieGee:

Anyone have any idea what might have gone wrong, I’ve no problem if someone says I was at fault. I just want to learn how to prevent/recognise this in future?

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• Something could have been clogged or damaged. Tanks, especially rental tanks can pick up crap inside that clogs the regulator.
• Your SPG may have been stuck. As mentioned, it doesn't take much to fill a BC. You might have been almost outof air, but still had a little for the BC on the surface.

As for a solution, you've probably realized that "air is important"

The solution is to make sure that you're always close enough to "different air" that you can get to it if yours suddenly stops. This means staying close enough to your buddy and keeping your skills sharp, or staying close enough to the surface that surfacing isn't a problem, or bringing your own redundant air source with you. (a pony bottle)

While it's important to keep track of your air using your SPG, it is possible to not have any air to breathe, even if the tank isn't empty. A poorly maintained tank can clog, as can a poorly maintained regulator.

flots

+1 on the pony. I never dive without mine. +1 on using your own equipment. I also learned how to maintain & service it myself. The only things I rent are tanks and weights.

Steve_C:

What equipment was changed between this and the other dives? Just tanks or the rest of the equipment?

Could have been a problem with the first stage.

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On the second dive I gad a different first stage hoses, regulators etc. And of course a different tank. I remember thinking that this equipment just seemed to breath better(?)

---------- Post added April 30th, 2014 at 06:28 AM ----------

krawlings:

First I would like to said glad all came out well for you both. Next I would say I would not have dove with same equipment after that till I or some one check said equipment . .Maybe ask a fellow diver / daughter to put there 1st/2nd stage on your suspect tank and verify.(all so some may have a tank gauge to check pressure)Until then I would call my dives ,There is always another day to dive

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I was a little shaken and was concerned with my daughter but in hindsight would have loved to do just that - try to narrow down the fault. But as I said I used different equipment for the next dive and the dive shop assured me the original equipment would be checked/serviced immediately. (I never did get a definitive explanation though)