Disorientation and uncontrolled ascent on night dive

[Iralub]

I had a rather embarrassing (not to mention frightening) incident on a night dive recently.

The first night dive I did, about a year ago, I suffered from disorientation on descent (turned upside down). Since then I did six night dives with no issues whatsoever.

On a recent night dive (my eighth night dive), I was having a nice, relaxed dive, until about 45 minutes into the dive I became disoriented and ascended in an uncontrolled manner. I'm not sure why or how it happened - one moment I was perfectly fine, neutrally buoyant and then suddenly, I could see people oriented strangely and apparently descending.

I realised that they weren't descending, I was ascending and I was spinning around! I tried signalling with my dive light with rapid side to side movements, but neither my buddy nor the dm noticed. I was later told that another diver in the group did notice but didn't know what it meant.

I couldn't locate where my bubbles were to determine horizontal or straighten myself out. As soon as I realised that I was ascending I started exhaling and tried to dump air from my bc, but couldn't arrest the ascent and ended up on the surface. Don't know how fast I ascended, but I'm pretty sure it was less than a minute from about 15m depth. My ascent rate alarm on my computer went off at some stage, but it's pretty sensitive and has been known to go off if I raise my arm too fast.

Once I arrived on the surface (pretty freaked out), I inflated the bc and signaled to the dingy which was waiting for us and informed the dingy driver that I had an uncontrolled ascent with no safety stop and may need oxygen. I wasn't so much worried about skipping the safety stop, but I didn't know how fast I ascended and it was the fourth dive of the day. However, I was on nitrox, the dive wasn't very deep and my computer was showing modest tissue loading on conservative algorithm.
The rest of the group surfaced a couple of minutes later and were picked up before we returned to the main boat, so it was about 15 minutes before we got back to the main boat. I kept breathing from my nitrox tank (32%) throughout, just in case.

When we got the main boat I informed the cruise leader of the incident, but he didn't think I needed oxygen as it was about 20 minutes since the ascent and I had nil symptoms of anything (other than fright). I didn't develop any symptoms of DCS or anything else and was back to diving as normal the next day.

Things I did badly included getting disoriented in the first place (I honestly don't know how it happened), losing control of my buoyancy (again, I don't know how it happened) and then not being able to re-establish either. If anyone has tips on improvement, please let me know. I think I'll try to make sure in the future that I always have some point of reference and pay constant attention to it on night dives.

I wasn't able to communicate to my buddy or anyone else in the group because they either didn't notice or didn't know the distress signal. It is probably a good idea to make sure everyone knows that waving of torch of side to side means "problem" rather than "come and see this cool critter"!

Things I did ok are probably making sure that I was exhaling as soon as I realised I was ascending, so avoiding lung over-expansion and establishing buoyancy on the surface before I signaled for pickup. There's no doubt that I was freaked out and not a model of calmness, but I don't think I was panicked to the extent that I wasn't thinking. I don't think that breathing from nitrox tank had any effect whatsoever, but I still had half a tank and figured it wouldn't do any harm.

Feeling a bit embarrassed about the whole incident, really.

 

[boulderjohn]

Some random thoughts...

If you have what is normally considered a pretty good breathing rate for an experienced diver, and if you were at about 15 meters for 45 minutes, then you would have used nearly 60 cubic feet of nitrox, which is about 3/4 of the common aluminum tank. You said you had half your tank left, so maybe you were using a larger tank. Whatever size tank you used, you had gone through maybe as much as 5 pounds of gas at that point, so you were that much more buoyant.

I would assume it took you less than a minute, but you should be able to tell by looking in the dive log of your computer. If it had taken you a minute from that depth, that would have been a little slower than the old recommended 60 FPM ascent rate. Most uncontrolled ascents are much faster than that. Still, your description sounds as if it did take a while, long enough at least for you to realize something was not right, look for your bubbles, signal for help, try to dump air, etc.

If the other divers seemed oriented strangely, it obviously sounds as if you had somehow gotten yourself into a head down position. How did you try to dump air from your BCD? If you tried to do it using your inflator hose, then that was not going to work. Air wants to go up, so the only way it can leave a BCD during a dive is if it is going through a vent at the highest part of the BCD. If your head is down, that will be the dump at the bottom of the BCD, if yours has one. Some do not.

I have no idea what your weighting was like, but overweighted divers frequently have trouble of this sort. The weight you carry has to be balanced by the amount of gas you put in the BCD. If you are overweighted and neutrally buoyant at depth, then you will have a lot of gas in your BCD to balance that extra weight. That gas will react to changes in depth. A properly weighted diver in a light wet suit will have very little air in the BCD--nearly none at the end of the dive with a near empty tank. Such a diver will be able to control buoyancy easily. If the BCD has a lot of gas in it, though, and if the diver ascends a little without realizing it, the expanding gas will start pulling the diver to the surface, and it can happen quickly.

The crew was right in not treating this as a serious emergency. It was not an ideal ascent, but it happens. A safety stop is not a requirement, and your rapid ascent increased the odds of a DCS event, but those odds were very small to begin with.

 

[TSandM]

Oh, dear -- I read this, and flashed back on so many experiences I had in my first couple of years of diving. I vividly recall wondering why the current was pushing me violently away from my buddy, and realizing there was NO current, but I was headed for the surface. I also remember doing a midwater nav dive in an AOW class with NW Grateful Diver, where I looked over at my buddy and wondered why he was vertical, head up in the water, when he was too good a diver for that . . . only to realize he was horizontal, and I was the one who was head down!

You sound like me -- very dependent on visual information for your orientation in space. Low viz, which is the norm in Puget Sound, and the lack of gravity as an orientation cue, resulted in me very often not being sure of how I was oriented. Disorientation led to anxiety, which led to more than one uncontrolled ascent.

It took hundreds of dives and several years for me to get it pretty much nailed down. First off, I need as much visual information as I can obtain. For night ascents, I ALWAYS ALWAYS shoot a bag and use the line for orientation, and I also ALWAYS stay where I can see my buddy, who also gives me useful visual reference info. In addition, I am VERY careful about head movement in midwater or at night. A friend who is an instrument pilot gave me that tip -- apparently pilots on instruments are prone to vertigo if they move their heads rapidly, and this certainly seems to be true of me. I have also learned to key in very carefully to how my gear feels on my back, and where the air is distributed in my dry suit.

I have gone from that "Why is my buddy receding?" state, to being able to do long lights-out exits in cave classes, but it took time and a lot of determination to get there. I hope some of these hints help, and even more, that learning somebody else understands EXACTLY what you are saying, is reassuring. I posted a lot about this on this board, the first couple of years I was diving, and nobody else seemed to have the same problems, which was demoralizing.

 

[spectrum]

Night diving with its limited field of view can set you up for some strange illusions especially if you are in a flat barren area. In any case the existence of a slope can be easy to miss. If you happen to unknowingly ascend along the bottom and don't pick-up on it you can find yourself in an unintentional ascent situation. It's then easy you get overloaded with handling a light, signalling buddies and dealing with orientation. One miss step like using the inflater dump while head down (Like BJ mentioned) and la la lal loom up you go.

BJ pointed to possible over weighting and that can make for difficult control. It's equally possible that you have perfect weighting with some cylinder but your cylinders are not consistent. Even if you are consistently using AL80s there is some difference between brands and you could find your self going buoyant as the cylinder contents deplete. If you are actually using different cylinder types the same is possible.

Once something starts to go south it almost inevitable that your lung volume will soar and with it your buoyancy. I your weighting is borderline the cylinder getting light and you skip a beat away you go.

Getting on the same page with signals is imperative as they are not consistently taught or understood.

Pete

 

[AJ]

Bad vis or no vis at all is a challenge, even for experienced divers. I dive regularly in a local pond with very bad vis. Even after 70 or more dives in that pond with bad vis it is still a challenge to keep my orientation. I had my share of getting lost and unplanned ascends. At some time I learned to rely on my computer, my compass and my gut feeling to know what is going on.

So don't feel bad, it happens to everybody. Experience and training is key to getting a better diver in these circumstances.

 

[Zeagle Eagle]

Where was your buddy during all this?

 

[DavidFL]

Oh, dear -- I read this, and flashed back on so many experiences I had in my first couple of years of diving. I vividly recall wondering why the current was pushing me violently away from my buddy, and realizing there was NO current, but I was headed for the surface. I also remember doing a midwater nav dive in an AOW class with NW Grateful Diver, where I looked over at my buddy and wondered why he was vertical, head up in the water, when he was too good a diver for that . . . only to realize he was horizontal, and I was the one who was head down!

You sound like me -- very dependent on visual information for your orientation in space. Low viz, which is the norm in Puget Sound, and the lack of gravity as an orientation cue, resulted in me very often not being sure of how I was oriented. Disorientation led to anxiety, which led to more than one uncontrolled ascent.

It took hundreds of dives and several years for me to get it pretty much nailed down. First off, I need as much visual information as I can obtain. For night ascents, I ALWAYS ALWAYS shoot a bag and use the line for orientation, and I also ALWAYS stay where I can see my buddy, who also gives me useful visual reference info. In addition, I am VERY careful about head movement in midwater or at night. A friend who is an instrument pilot gave me that tip -- apparently pilots on instruments are prone to vertigo if they move their heads rapidly, and this certainly seems to be true of me. I have also learned to key in very carefully to how my gear feels on my back, and where the air is distributed in my dry suit.

I have gone from that "Why is my buddy receding?" state, to being able to do long lights-out exits in cave classes, but it took time and a lot of determination to get there. I hope some of these hints help, and even more, that learning somebody else understands EXACTLY what you are saying, is reassuring. I posted a lot about this on this board, the first couple of years I was diving, and nobody else seemed to have the same problems, which was demoralizing.

+1 to this

As a commercial and military pilot (Navy; aircraft carriers) and flight instructor I can confirm from personal experience that everyone who spends any time in an environment 'separated' from the normal on-to-ground-in-one-gravity environment within which we evolved....and further loses visual contact with some kind of horizon or other reference...will sooner or later have the same experience you had. One of the biggest challenges in teaching instrument flying is convincing rational human beings to stop relying on their instinctive sense of orientation. In flying, we can supply artificial horizon and other instrumentation. In diving at night TSandM's suggestions from her experience are great substitutes. Glad the ascent didn't have any more permanent consequences.

 

[dumpsterDiver]

Don't feel bad it happens to everyone??????? Lol it is potentially fatal accident. Not that unusual but iit is bad. The biggest issue I have with the scenario is that the op thinks that the initial strategy is to wave lights and signal. That is a total Fail !! You need to exhale hard and fast and take care of yourself. There is no way a buddy is going to know wth a waving light means in the dark and then what are they to do., shoot up and rescue you??? Completely wrong mindset

 

[Iralub]

Don't feel bad it happens to everyone??????? Lol it is potentially fatal accident. Not that unusual but iit is bad. The biggest issue I have with the scenario is that the op thinks that the initial strategy is to wave lights and signal. That is a total Fail !! You need to exhale hard and fast and take care of yourself. There is no way a buddy is going to know wth a waving light means in the dark and then what are they to do., shoot up and rescue you??? Completely wrong mindset

My initial strategy, as soon as I realised I was ascending, was to exhale and continue doing so as I tried to dump air from bc with my left hand. The dumping of air didn't work, no doubt for reasons that boulderjohn identified - I wasn't oriented correctly.
I was also trying to find my bubble stream to establish reference but I couldn't.

At that stage I tried to signal to the rest of the group with the torch in my right hand, while continuing to exhale and continuing to try and dump air with my left. I can't remember if I tried one of the rear dumps as well or just the inflator.

So I think we are in agreement as to the appropriate first response - exhaling.

I'm not sure what I expected anyone to do if they noticed my signal - I was trying to communicate I'm in a spot of trouble and it wasn't as though my right hand was doing anything else. I think signalling was just an instinct thing, but if I'd arrived on the surface unconscious or something, it may have improved my chances of people had seen the signal.

---------- Post added July 20th, 2015 at 01:50 PM ----------

TSandM, thank you so much for those tips. I'll certainly take them on board. It is also very comforting to know that very good divers are not immune to those problems. I'm feeling a bit less embarrassed about it. (Although as DD points out, I realise this was a potentially dangerous situation).

Boulderjohn, I was diving an Al63, which was initially filled to 230 bar. Looking at my log, on 45 to 50 min dives to comparable depth, where I was not moving much (eg drift or night) it is not uncommon for me to have 70 or 80 bar left with a 200 bar fill in that size tank. So I will have had about 100 bar remaining in the tank when the problem began (hence the half a tank comnent). I think I had 80 bar left when I got to the main boat, but my recall is not 100%.

I don't know if I was over weighed. I had a little under 6kg in 5mm suit, with lavacore undergarments. I usually have 3.2kg in 3mm suit. I couldn't descend with one less weight, but as this was a night dive I was carrying two torches, so maybe extra half kg. May well have been a bit overweight, plus air use, plus not being used to diving in 5mm wetsuit and the greater buoyancy changes than 3mm. I will certainly be paying more attention to buoyancy changes in the future. Thank you

 

[Patoux01]

The biggest issue I have with the scenario is that the op thinks that the initial strategy is to wave lights and signal. That is a total Fail !! You need to exhale hard and fast and take care of yourself. There is no way a buddy is going to know wth a waving light means in the dark and then what are they to do., shoot up and rescue you??? Completely wrong mindset

It was completely obvious to me that he was trying to care of it as well. If you can't wave your hand and exhale at the same time, you shouldn't be underwater. Signalling a problem should be done immediatly when noticing it, while taking care of it. If not possible, then you take care of the problem and signal afterwards.

As has been said, if for some reason you can't trust your senses, your computer (or depth gauge) most likely will be able to help you out.
Also, rather than looking for your bubbles, you might be able to "feel" them rolling against your body.