uncontrolled ascent

[appleofthesea]

Dear fellow divers,

I recently experienced an uncontrolled ascent from 55 feet. Of course it was a very negative experience. I want to prevent that from ever happening again.

I am still a new diver. Only 15 dives so far. In general I have had pretty good buoyance control for a new diver. At the worst I had to just fin a little bit to stay neutral occasionally but I always felt in control. My dive buddy is also a new diver and I was always the one helping her stop from ascending uncontrollably. I was extremely disappointed in myself when this happened. Of course the main thing is the fact that medically it could have been a lot of trouble. But more than that I just felt like I was a responsible diver that was doing well for being so new.

We descended to about 40 feet initially. The total bottom time was about 33 minutes. We swam more slowly deeper and hung out mostly at about 60 feet. I couple of times we dipped down to around 77 feet from there. Finally we decided to turn around and swim back slowly so that we could decompress slowly. We swam out of the canyon and prepared to swim back along the bottom.

Somehow swimming out of the canyon I just remember at one second looking at the rippled bottom then the next I was ascending -- from about 55 feet. I tried to dump air quickly but I kept rising and could not dump fast enough. I was accelerating and started to feel nervous and uncomfortable. I could not slow it so I knew at least I had better keep breathing. I did so but as I got very near the surface the speed of the ascent knocked my second stage out. The last 10 feet I think I had no reg in my mouth but I remember still that I knew I had to breath to avoid lung overpressure so I think I must have just been exhaling in bursts.

Then I popped up at the surface. Stunned. I collected myself as quickly as I could. I realized that my lungs and chest felt ok. My buddy, who is less comfortable below than I am (as I said, usually I have been helping her -- despite how this story sounds I was always careful before and tried not to push limits). Since she hadn't come up, and since I was worried about bends I swam back down following her trail of bubbles. I found her at 50 feet and we swam back slowly at the bottom. At some point I let her ascend (maybe at 15 feet or so, but I kept going back slowly at the bottom). She had a lot of air left, and I was getting near to the end of my limit (not too much over 500 psi) so as we swam slowly at the bottom I used her octo. Then I just let myself go to 400 so I could decompress a bit longer then I ascended at 9 or 10 feet.

I was really worried and so disappointed in myself. I don't want it to happen again so I am laying my story out for you. I know I made mistakes but I am still here to learn from them. I just do not understand how I began the ascent in the first place. I didn't add air, and I shouldn't have just started going up that fast. Usually if I am slightly positive I have had no problem dumping a little air. I think it could be that I just looked up for a second, the viz wasn't too great, and I just lost my frame of reference with the bottom. I cannot think of anything else.

Could you please give me advice? I am serious about diving and I love it and want to be the best diver that I can be.

Thank you so much in advance.

--L

p.s. I called DAN and everything and it has been a week now so I am ok.

 

[IceBergSlim]

Well, I guess you are ok for now. But, I figure that you are gonna catch some crap from this board soon. Peace on you and keep diving, DG

 

[chrisch]

We've all had problems in our early days - I hope people don't post negativley on this. Try a bouyancy course if you think it will help. PADI do one (I have no experience of it - sorry). It will, if nothing else, restore your confidence. Meantime keep your diving in the shallower ranges.
Stick at it - its like riding a bike - just hits you one day..
Best wishes
Chris

 

[Snowbear]

...At the worst I had to just fin a little bit to stay neutral occasionally but I always felt in control...

A question - do you find you need to fin to keep from ascending or fin to keep from sinking? When you are truely neutral, you should not have to fin to maintain depth. When you're neutral, you should be able to ascend or descend by inhaling or exhaling. Yep, this takes practice! Practice remaining neutral in shallow (like <15') water without using hands or fins, then slowly inhale to rise a little, then exhale to sink. Remember that the change will not be instantaneous, it takes a couple seconds to start rising when take a breath. As you start to rise, exhale - give it a moment, you'll start sinking. If you can master this in shallow water, it'll be really easy in deeper water. Is there a more experienced diver around who can help you and your buddy with this?

 

[IslandHopper]

You said you were trying to figure out how it happened... how it got out of control so quickly...

(you may already know all this) ... just the opposite of when you descend ... as you ascend, your wetsuit (and BC) uncompress and become MORE bouyant ... hence the need to release air from your BC as you climb. The thicker your wetsuit, the greater it's effect on this issue. Once you get "too bouyant" and start to ascend, the more you ascend, the more bouyant you become and the whole process just accelerates on itself. As you discovered first-hand, this can happen quite quickly.

Don't feel bad, just learn from it. Make sure you know where all the "dump valves" are on your BC, and how to grab them in a hurry ... If you can open more than one valve (say your deflator AND a shoulder dump), then you might be able to get back under controll. In any case, I get the impression that you won't let it happen again anyway. (Experience being the best way to learn something)

 

[crispos]

A fundamental aspect of being a safe diver is control. There are so many aspects to this....dive planning, proper weighting, gas management, keeping neutrally buoyant, buddy communication, etc. etc. You lost control, maybe the first time, and you are pretty shook up about it.

The good news is you remembered to keep breathing, and kept your airway open during the uncontrolled ascent you made. This probably saved you from injury or even worse.

There isn't much to say except a few tips: sounds like you and your buddy are pretty ambitious and going to 77 feet after very little experience. That can be good (you love diving) but maybe practice more before going deep. And consider taking more courses which include deep diving and buoyancy practice. This way, a dive instructor can help you improve your diving skills/habits.

Second, when you are excited and looking around on an interesting dive, you might forget some diving fundamentals - but you can't. For example, you didn't dump a little air before coming out (high) from the canyon, you didn't notice you were getting abit buoyant. Also, your buddy probably didn't even see you take off. Probably you weren't within an arm's length. What could have the buddy done? Not a whole lot, but perhaps hold you until you managed to dump air. That is assuming your buddy wasn't also too light.

Make sure you are properly weighted for the dive (it sounds like you were OK, but that may or may not be true). So many people take a cavalier approach to weighting. You should have a log book showing the type of suit used, tank, whether fresh or salt water and exactly how much weight you used to be neutral. Then refer to your log book before diving, and still insist on doing a buoyancy check before descending on every dive.

Check the chapter in the manuals on how to do a proper buoyancy check. Remember that an Al 80 loses about 4 pounds of weight if it is breathed down 2/3. It sounds like you already know this stuff, but it can't hurt to review it.

I hope you don't make a habit of diving your tank below 500 psi. If you are always breathing more than your buddies, consider a steel 98 which also has better buoyancy characteristics (tends to require less weighting and stays neutral even when almost empty).

Keep that low pressure inflator (LPI) hose in your left hand during the dive, and make little adjustments as you dive. Find the dump valve in the bottom of your BCD, and get practiced at dumping air when horizontal, that is what it is there for. This way, you can dump air without having to tilt upwards.

If the bottom is flat, you can basically leave the LPI alone once you are perfectly neutral at the bottom. But in a varied bottom, you have to make frequent adjustments. Keeping the hose handy will allow you to avoid the beginning of the rapid ascent you experienced. Once it gets going, the rapid ascent is hard to stop. But you can get into the "flaring" position. On your back, facing the surface, hands and legs outstretched like a star. This should not be practiced in Open Water unless under supervision. Another rapid ascent culprit is if a weight belt buckle failed, so this is a useful skill to know.

Get a computer with a rapid ascent warning beep. This way, if you hear the beeps, it will warn you that you are beginning to rise abit too fast. Learn to dive so you never hear a beep. You can track depth easier if it has a big illuminated screen with digital readout. Wear it on your wrist for easy access.

Finally, don't get caught in this trap that "I am a great diver so I will go around taking care of people and assisting lesser divers". It is nice that you want to take care of your buddy. But sometimes it is better to dive with people more experienced than you are, so you can continue to improve your own ability, and save yourself from injury.

OK, safe diving, and have fun (in that order)!

 

[MB]

Most of the replies have been helpful and you can learn from this. Let me point out a couple of things you might not have considered.

1. Couldn't dump air fast enough? That makes me wonder now much air you had in your BC at depth. If you had a whole bunch of air in the BC to stay neutral, then that makes me wonder whether you started with too much weight. Lots of things are related here, and it takes some work to see how one factor might affect several others. But if you are overweighted to start, you'll end up needing LOTS of air to stay neutral at depth. Then, on ascent, there's a whole bunch of air that has to be dumped quickly. Key -> re-check your weight needs before your next dive. (see previous reply, and yes, write it in your log, along with your neoprene configuration and water temp.)

2. Stiil on the idea that you couldn't dump air fast enough. Modern BCs have a tremendous capacity to dump air; unfortunately we can screw that up in a number of ways. And... air is easily "trapped" in any number of places in a BC. So, what to do??? First, lots of folks dump air from the inflator hose but never raise the hose high enough. They hold it at chin level, or out in front, or even try to use it without raising the opening to the highest point (i.e., they swim down, and hold the hose infront). If this happens, any air in the BC that is above this will have to travel "downhill" to be released. It won't do that. The result is that only some air is released. Even in my BC, which is a bit too big, I have to make sure that I release the little shoulder velcro thingie so I can extend the hose straight, and up. Only this allows me to vent the air, and not have any trapped.

3. OK, still on not venting fast enough... Most modern BCs also have a cable inside the inflate/deflate hose. If you pull the hose (and thus the cable) you have a tremendous dump of air from the valve at the shoulder (instead of thru the hose itself). If you are in a vertical, heads up position, that fast dump will release the air. (Some folks will tell you not to use that - maybe you'll pull your hose off the BC - ok, so don't pull on it like a gorilla - and do inspect your gear before you dive with it. Its a good tool, particularly useful for situations like you describe.)

4. What would happen if you quickly went head down, and used those wonderful human things called legs - with FINS - to slow your descent? Kicking toward the bottom, assuming you have any quality kick, will slow your descent. Add to that the thrid way that most BCs release air - a release valve at the bottom of the BC, and you have yet another way to vent air. If you are head down, the air in the BC is now moving to the base of the BC, which is by your hips, but closest to the surface. If your BC has a release valve there, you release air while you are swimming toward a better depth.

5. Last point - a bit of ambiguity in your post, but if you had been to 77' and were at 33 minutes, you should re-examine your profile and re-work your tables. That dive was very close to your time limit. Your decision to return to 40' after maximizing your nitrogen load wasn't a good one. With your tissues full of nitrogen, and the N2 trying to bubble from an uncontrolled ascent, and then with a return to depth to acquire more N2, you could have hurt yourself from the post-ascent actions. If you miss a safety stop, you can generally get back to the stop and extend it, but returning to depth does nothing good to your tissues. Concerned about your buddy? Good point, but I'm assuming your buddy had some knowledge that you were gone. If she's at 40', and you're at 15' but above her, let her come to you. (Note: I'm assuming you had some visibility - 25' - so you could locate one another???)

Hope I didn't provide too much at one time. Glad you're safe and sound. Use this one as a learning dive.

 

[ScubaRon]

It is good to hear that you're OK and willing to learn. Your experience brings up 2 questions:
1. Why did you start an uncontrolled ascent?
2. Why couldn't you stop it?

Re. question 1 I wonder if you were "following the bottom". This is a common beginner's mistake: to your eyes the bottom looks level, but in reality it slopes a little and you can easily ascend unknowingly this way and thus become positively buoyant. Unconsiouscly you may have been finning down a little too to compensate for this. A sudden small ascend of sometimes even just stopping can easily cause the beginning of an uncontrolled ascent.
To avoid this make sure you regularly check your depth gauge, also in seemingly level places, and learn to feel buoyancy chances.

Re. question 2: you should have been able to stop the ascend by dumping air. Some possible reasons why you couldn't could be:
- trying to dump from a valve that is not "on top"; a common mistake is an overbuoyant diver trying to swim down and at the same time trying to dump from a shoulder-valve.
- pressing the inflate button instead of the deflate;

Try to analyze what went wrong so you won't make the same mistake again.
And enjoy!
ScubaRon

 

[cornfed]

Of course it was a very negative experience.

Actually, it was a very positive experience!

 

[appleofthesea]

Dear everyone,

Thank you for the kind advice and being concerned about my safety. All of this advice is extremely helpful.

Regarding Snowbear's comments...I probably do fin a little too much trying to maintain position. When I find myself doing that I try to immediately adjust to get neutral though. In the past I never found myself sinking too much or rising too much, but I can see now I don't have the kind of control you are talking about. I'll try to keep practicing like you said so I can become sensitive to my breathing and buoyancy.

Island Hopper probably has a point. My wetsuit is a full 6.5mm with a 5 mm shortie. A lot of neoprene. Maybe that exaggerates the buoyancy gain as I ascend. Not an excuse...just something else to take into account.

Crispos also had some very good advice. It made me remember an important detail that I had forgotten to mention before. Each dive I have tried to use a little less weight. So I was using 1 lb less than my previous dive. I am down to 24 lbs (including a 6 lb plate). When I got certified I was up at around 30 or maybe even 31 my very first dive. Probably 24 might be ok, but it is getting close. After I have better breathing control maybe 24 lbs is ok, or maybe I should go back up to 25 again.

I think we have been too ambitious too. We felt confident because almost all of our dives were at the same location so we let ourselves go a little bit deeper and even when on night dives a couple of times. I think we might decide to do some more shallower dives and only focus on skills.

I may have been trying to fin down and also let air out. That might have caused a problem, or maybe I just didn't lift it high enough over my head (more likely). I now realize I should have flared better, dumped air effectively, and finned back down. In the past I always could correct with my fins (my buddy sometimes used to start to turn upside down when we got back to shallow depths and I had to pull her back down -- but now she is getting a lot better and more confident).

Cornfed -- it was a positive experience because I was ok. I have actually learned a lot. I was reluctant to post this because I knew I made a lot of mistakes and was disappointed. Finally I did though and learned more than I expected. I am not really into intentionally pushing limits or going deep just to say I was there. I think it was more just becoming overconfident because of familiarity with the site. I guess also since I love being out diving and have not found it intimidating I was not aware of my limitations yet.

I feel better and more aware and I have a lot to practice. The good thing is that practice means being out there diving! Even when we hardly see any animals I have fun just being out there.

Thanks again!