Uncontrolled Ascent Don't let this hapen to you!

[sailbahama]

I'll set this up as quickly as possible and give my thoughts, lessons learned, then would welcome anything I have missed or do not understand, but please leave out the "get more instruction" advice as I've already signed on for further instruction since this event convinced me it is the wise course of action. I'd like to learn from those level headed rational divers with more experience than I on this forum, in addition to taking a one on one with dive instructor.

One of the lessons learned is something I haven't seen discussed here and wasn't given much attention in my open water classes, but, in my opinion, ALL beginning divers should practice frequently dumping air from their dump valves and not just dump air from the inflate/deflate hose. Not having practiced this got me in real trouble, real fast.

On my 20th dive after open water certification I experienced an uncontrolled ascent from 57 feet all the way to the surface. Yep, it scared the you know what out of me. No injury, but I was lucky.

It was near the end of the dive and I had approx 1000 psi remaining. The dive to approx 80 feet had gone well and I was near the ascent line. While practicing bouency and trying to "hover" at 60 feet in a head up position, I rose slightly.

The slight rise quickly turned into a faster rise, at which time I tried to dump air from my "inflation/deflation" hose.

The ascent, very quickly turned into an expanding air in the BC scenario and I was unable to dump air fast enough from the "inflator/deflator" hose. In the panic that followed, did I hit the wrong button? I truely have no idea. The BC exapanded so rapidly, it leads me to believe that I hit the inflate button, but am not sure. The expansion could have simply been the result of the air in the BC rapidly expanding as I ascended.

The regulator remained in my mouth, but I can tell you that when the you know what hits the fan, don't be surprised if you don't remember if you were breathing, holding your breath, or exhaling. Since I didn't suffer a lung injury, I must have been breathing. Open water training instilled in me the thought to exhale if I'm out of air, but didn't prepare me for a rapid ascent, except to avoid one. laugh

Lessons learned.

1) just when you think you are becoming a capable diver and are getting comfortable, you might need to rethink that overconfident attitude.

2) check weighting. I could have been overweight, which would have required more air in the BC for proper bouency at 60 feet, which adds fuel to the expanding air fire.

3) practice dumping air not just from inflator/ deflator hose, but from BOTH dump valves. In my case, I had never dumped air from them since the swimming pool session and couldn't find them quickly enough when I really needed them. Why do open water courses not require this to be practiced over and over?

4) get control of an ascent quickly, don't let it even get slightly out of control. I was simply amazed at how fast an ascent can get totally out of control, thinking I would just deal with the unplanned slight rise by remaining in a head up position and dumping air from the inflate/deflate hose.

5) and this is just a question from a very inexperienced diver. Why in the heck do BC's have an inflator button positioned very close to the deflator button? Am I missing something here, or is this a fairly stupid design flaw? When needed quickly it is way too easy to hit the wrong button. This issue, of course is meaningless if one regulary dumps air without using this hose.

6) I now chose to think of the inflate/deflate hose as primarily an INFLATE hose and chose to think of dumping air, at least once at depth, from the dump valves. Am I wrong on this? Come to think of it, I don't every remember any of the dive guides I followed on my 20 dives using it to dump air once they are at depth.


Your thoughts very welcome.

 

[jonnythan]

You also might want to think about your breath. Often when going into a panic mode, as can easily happen when you notice yourself heading up when you don't want to, you take big huge lungfulls of air which makes the problem 10 times worse. The first reaction to an undesired decrease in depth should be a quick but steady exhale as you reach for the dump valves.

 

[dlent]

I'm glad you were not hurt. Practice using those dump valves. If your bc has a valve on the bottom you may want to consider swimming straight down and dumping air at the same time. If the BC keeps inflating disconnect the inflator hose. In training I had a BC that keep inflating on it's own and I had the same problem you just had.

 

[do it easy]

5) and this is just a question from a very inexperienced diver. Why in the heck do BC's have an inflator button positioned very close to the deflator button? Am I missing something here, or is this a fairly stupid design flaw? When needed quickly it is way too easy to hit the wrong button. This issue, of course is meaningless if one regulary dumps air without using this hose.

6) I now chose to think of the inflate/deflate hose as primarily an INFLATE hose and chose to think of dumping air, at least once at depth, from the dump valves. Am I wrong on this? Come to think of it, I don't every remember any of the dive guides I followed on my 20 dives using it to dump air once they are at depth.

Points 1-4 are all very good!

Regarding 5, as you get more comfortable, you'll need to use the inflator/deflator less often, and less urgently. I usually put a hand on it any time that I'm planning an ascent. I might let it go momentarily, but when I'm thinking up, the deflator is ready.

Regarding 6, if you are diving a square profile, or staying at roughly the same depth, you won't have to play with your BC at depth (minor adjustments aside). I also suspect that the guides were weighted pretty well and using lung volume to control most of their buoyancy.

Glad you survived to share this.

 

[do it easy]

I think that I misread your question in #6- I think that it is common for people to use the dump valve at depth, depending on swimming position. In my BC, I'll use the rear dump at depth, and the deflator for ascending, although I consciously raise it up. In my BP/W- it's strictly the inflator/deflator. I have a dump on the wing, but I just don't use it.

The point to remember is that the deflator and dump valves work best when they are at the highest point. This means if you're swimming head down, a shoulder dump may not work.

 

[Sideband]

The inflator hose dumps slowly for a reason. When making buoyancy adjustments at depth you don't want to vent large amounts of air for a relatively small depth change. The pull dumps on the other hand will vent faster than the inflator will fill.

In our classes we spend time practicing reaching all of the different dumps. We have the students close their eyes and then we tell them something like, "Left hand, shoulder dump. Go." We have them use different hands and have them add or dump air until they know where each is. The only problem here is if they buy gear with different dump locations. We do make this a part of the instruction though.
As someone else mentioned, swimming down and using the rear dump isn't a bad idea.
Glad you are OK.

Joe

 

[TheRedHead]

I would advise you to keep in a horizontal position. You mentioned you were trying to hover veritcally. Your body will follow your head and air rises so when you feel yourself moving up that's the time for you to invert yourself and fin down.

You may have shot some air in your BC instead of hit the defaltor button and you probably gulped great breaths of air from your regulator and moved your fins which propelled you even further up. If you were wearing a thick wetsuit, the aircells sprang to life and became very buoyant again which further contributed to your ascent.

I seldom use my rear dump valve and it doesn't work well unless I'm finning down. I think it is very important to master buoyancy control before deep diving and I'm glad that you are ok.

 

[Sideband]

That's a very good point about being vertical and accidentally finning. It doesn't take much fin movement at all to increase an already unwanted ascent. On a different but related note, students that have trouble decending are almost always finning without knowing it.

Joe

 

[do it easy]

I second the horizontal trim! It's great for ascents since it forces you to use buoyancy control to ascend, rather than finning up, which can mask your buoyancy until it's too late. There are also advantages for descents too!

 

[radinator]

Another reason to maintain horizontal trim is that you are presenting a lot of drag for up/down movement which will help your control. Also, I didn't see any mention of flaring out your arms or legs to try to slow the ascent. You may have done it and not mentioned it, or you didn't do it. Either way, it's something to keep in your toolbox for next time.

Glad everything turned out ok.