sudden uncontrolled ascent!

[sibermike7]

I weigh 200# and use only 6# in salt water with a 3MM full suit you might be overweighted.

This could very well be your problem (or at least a contributing factor).
I also weigh 200# and use 6# in salt with 3MM. If you are over-weighted then you'll have a tendency to over compensate by adding to much air into the BC.

Nice analogy TC!

Don't want to sound critical, but me thinks you may be rushing things a bit: 90' of water with only 20 dives under your belt may be moving too fast. You probably missed some pretty good diving in the 20-50' range trying to get there (90') so fast! I would recommend slowing down and really getting some skills down. I know that when I started diving I wanted to do everything by day/dive 2. I tried to get something new out of every dive.

Over time, I learned to plan some (many) dives just to practice and re-practice skills. ALL of your dumps on your BC should be committed to memory. Concentrate on grabbing them throughout the dive even when you are not using a particular one, you should know instinctively where it is located. It is the rare dive that I don't go through some skill set, even if it is something simple like mask clearing or octo exchange, and I have been diving 26 years!

Thankful that you go through this, THANKS for sharing!!, and great to hear you willingness to learn from it and grow!

 

[Blackwood]

Advanced Scuba Discussions?

The good thing is that I was completely relaxed, I breathed normally and upon reaching the surface, I grabbed the line and went down again, to do all the required precautionary stops.

Can you elaborate? Were they required or were they precautionary?

FWIW (and it may be W very little), there are (at least) two schools of thought on what you did. One is that it's a good idea, the other is that it could be a very bad idea.

If your uncontrolled ascent from 90 feet caused any bubbling, descending again will compress those bubbles, possibly enough that they can pass the blood gas barrier. It's suggested that if your re-descent is sufficiently short (on the order of a "safety stop"), you may do more harm than good, taking a possible asymptomatic or type I hit and turning it into a type II hit.

 

[dmoore19]

Hi, I have over 20 dives under my belt. Last week, in the Caribbean, I had an uncontrolled ascent from 90 feet all the way to the surface. I was using nitrox.

I am just curious about nitrox. Is it possible to have a nitrox cert that soon with your diving experience? I am not trying to be critical because I am not that experienced and really don't know. I do know I wouldn't want to be at 90 feet yet.

 

[fisheater]

That shouldn't be too surprising. One can take AOW right or soon after OW, and be certified to 100'. Heck, you can then take deep diver and becleared to 130'. You can also take nitrox class with OW.


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[Mr Carcharodon]

Staying mostly horizontal is probably a good idea since you present more surface area to the water on ascents and descents and that makes those more controlled. But typically for Open Water courses they teach dumping air from the shoulder dump while being nearly vertical in the water. That works but is less controlled than being horizontal for the reason just mentioned. But when horizontal it is easier to use the rear dump valve. It sounds like you did a hybrid technique (shoulder dump while horizontal) and learned it did not work!

You may want to practice some in shallow water. Try feeling the bubble with your hand. Pitch forward and back, and roll side to side and try to feel the bubble move. And try the different dump valves with the bubble in various positions and see what happens. Once you know what you are looking for this should take just 20 minutes of playing around to figure it out and then you will have it nailed.
Also remember if you are a just a bit buoyant you can swim down and your buoyancy will decrease as the gas in your BC is compressed. And you can do the reverse when you are a negatively buoyant.

So if find yourself floating away again swim down and since you will be tail up dump air from your rear dump valve.

And as mentioned having your weighting about right helps since there will be less gas to vent. But don’t overdo it. A pound too heavy is better than a pound too light.

 

[TSandM]

One of the things that really hasn't been mentioned is narcosis.

I would assume that you have done 20 dives without having this kind of catastrophic buoyancy problem -- and let's not minimize this, it was very dangerous what happened to you. If you have done 20 uneventful dives, and then blew yourself to the surface, my strong suspicion is that your judgment, your perception, or your motor skills weren't what they should have been at 90 feet. If your training were horribly deficient, you should have been having buoyancy problems at all depths, and worst when shallow (where small volume adjustments get magnified very quickly with depth changes). If this was a totally new issue, think about narcosis-related impairment, and perhaps you might choose to avoid such depths until your diving mechanics are more thoroughly reliable.

Were you diving rental gear? That can also affect your understanding of how much to hold a button down, and how and where to dump gas. I would always do the first several dives in unfamiliar equipment at conservative depths. It amazes me how much even changing my gear a little bit impacts the things which have become more or less reflexes.

The decision to descend again has to be a case-by-case one -- if you had been at depth for some time, it was probably unwise to do it. Should you have developed DCS symptoms while underwater, it would have been far more difficult to rescue you. On the other hand, if it was the first dive of the day, and you had just arrived at depth, you might well have been able to re-descend and continue.

At any rate, thank you for posting this story, because uncontrolled ascents are not rare with new divers, and buoyancy control problems feature prominently in the causes listed by DAN for fatalities and DCS events in new divers each year. If someone reading this can learn a little bit about what to do to avoid a similar problem, you have contributed a lot.

 

[AfterDark]

The talk of being narced is right on target IMO. Narcocsis can be VERY sutule. The 1st time it happened to me I didn't know I was narc'd. We were @ 120 fsw diving on the submarine LS1, we'd found a deck cleat that we wanted to recover so we over stayed our planned bottom time. We had the air to do it and I was lucid enough to know it would change our decom time, but I couldn't do the simple math to figure out how much! Pre computer days for all you youngin's. At that time I realized I was narc'd! We ascented to 20' were it was a simple matter to change the stop time! Narcosis is a stealthy demon, it makes you play tricks on yourself.

 

[scubazachary]

you should have been able to control your asent buy swimming down, slowly. to slow your asent.

 

[vkalia]

How can I avoid this from happening again, especially if I feel that I am going a little down. Also, is it possible that I might get any symptoms in the future or not?

For starters, fix your weighting. If you are diving in tropical waters with a thin wetsuit, you shouldnt be too negative even with an empty BCD and a full suit. A lot of OW divers are over-weighted, b/c instructors seem to find it easier to teach students when they are carrying a few extra kilos. This is turn causes you to add more air to the BCD and so buoyancy shifts with changes in depth are higher.

You shouldnt suddenly become negatively buoyant either, unless you gear has a leak - so before adding air, breathe in a little more deeply than normal and exhale slowly and see if that starts to bring you up.

Lastly, if you need to add air, do so in VERY small squirts, atleast until you get a feel of how "negative" you are in the water. But you've already learned that.

Uncontrolled ascents happen sometimes and provided you dont hold your breath, it isnt always the "oh you were inches from dying" experience that some people here make it out to be (which is not to say that you should make a habit of it, either - it *is* stressful on your body and does increase the risk of injury). Learn from it, put it behind you and don't let it affect your diving.

V.

PS: Narcosis on a warm water dive causing so much impairment at 90 feet as to cause loss of buoyancy? Really? While it is not impossible to rule it out, there is a very, very low probability of that happening. Let's not over-state some of the risks either.

 

[TSandM]

I didn't say narcosis caused a loss of buoyancy. I said I thought the OP's judgment about how much air was needed in the BC might be off, or their motor skills to limit the time pushing the button might be off.

One of my first narcosis episodes involved hallucinating at 100 fsw. I became convinced I was beginning an uncontrolled ascent, and dumped all the air out of my wing and drysuit (and of course, went splat! into the bottom). Had I been on a wall or somewhere with poor visual cues, I might well have thought I was sinking, and might have blown a similar amount of gas into the wing and ended up like the OP.