The 'snowball' effect

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Hammerhead

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A story with a few lessons I’d like to share.

Someone commented on another thread how mischance tends to snowball and I believe this is a good example of that.

I was diving in the Philippines on a ‘fast’ drift dive at maximum depth of 34-36m. Called ‘The Canyons’, it’s a must drift-dive for anyone diving Puerto Galera and is great on Nitrox. By this time I had probably already dived it 10-15 times over the years.

My buddy for the dive was an guy in his mid-to-late forties and a good friend, and I was in my mid-twenties. He and I had buddied up a few times before, and made a good partnership. I knew he could use up his air quite fast (a bit overweight and a smoker, as I am in fact, but I’m younger…), but then again, when you are aware of something you take it into consideration on a dive. For his part, he knew that I generally like to dawdle and investigate small things and was prepared to put up with me. Like I say, we were friends.

Anyway this was not intended to be a ‘dawdling’ dive, the tide was truly ripping through when we arrived by boat at the site, and you could see massive turbulence just from the surface. Our DM (an instructor & tech specialist) had dived with us 15-20 times, knew our styles and levels of competence very well. He took a look at the surface and told us that with this sort of current, there was a serious chance of becoming separated just on the descent.

We discussed it amongst the group (me, my buddy, the DM and the other guy, who was also quite an experienced diver. The conclusion was that we would go ahead with a quick swimming descent, and try as a minimum to maintain the buddy teams – any diver on his own would do the usual minute’s search before aborting. Intact buddy teams would continue with the planned dive.

Basically, we were after a fast drift and this was too good to miss as long as we accepted the basic buddy safety system – just as well we did.

To cut a long story short, my buddy & I got cut-off, but carried on with what was a spectacular dive (think Superman zooming through the Grand Canyon…well not quite, but you get the idea). All went to plan right up to the end when we had to do a blue water ascent with safety stop.

At the end of the dive, the bottom is sandy and & slopes downwards quite rapidly, you’re still being carried by the current, but now away from land into the main channel, and within minutes, you lose all points of reference.

After only a minute or two of blue water, I realized my buddy seemed a bit disorientated and was holding his gauge console and tapping it. He did not look distressed, so I swam over to him slowly and turned the gauge to face me.

We had planned to start ascent when either of us hit 70 bar / 1000 PSI, and knowing that it was likely to be him rather than me, this was what I expected to see, all I couldn’t figure out was why he hadn’t just signalled me. BTW we would have been perfectly safe waiting for 50 bar, but a little caution is a good thing.

His pressure gauge showed about 30 bar - not good, but overall we’re still in OK shape, I’m still on 95-100 bar, is what goes through my mind. For a minute, I was actually pretty happy with the situation – I had trained for emergencies and problems, and I was actually going to get a chance to put training and planning into action, a shared air ascent would be almost inevitable.

His console was one of the combined computer / pressure / compass designs, so while I’m looking at the pressure, I glanced down at the depth gauge and did a double take. We were at 53m / 175ft and sinking fast.

Not a lot of planning went into what followed immediately. I grabbed him and inflated my BC while swimming, not in order to surface, but to get to shallower water. This was not a situation I’d expected to happen.

Normally very careful about depth, how the hell could I have dropped like a stone?

The answer was twofold: -
a) nobody expected us to be carried as far as we had been by the current, certainly not as far as the down-draft that exists at the end of the ledge, so nobody had ever mentioned that it existed, and
b) We were narked. Simple as that. My buddy couldn’t figure out what his gauge was telling him, and I had got to the detached phase where I couldn’t see that any problem existed. We lost a couple of minutes that could have been fatal because we were stoned.

After the initial burst to about 20m / 66 ft his tank ran dry and he switched to my spare. At this point, I can’t remember exactly how much air I had left.

It had cost me a lot to pump into the BC, not to mention dragging my buddy up to about 35m / 120m where he seemed to click back to normal, kicking fast, and against the down draft.

We managed to maintain eye contact all the way up, not so difficult when you’re buddy is facing you and holding on to your BC’s shoulders so tight you feel they might tear! Not quite sure what our best course was, we went with my buddy’s suggestion to stay at 5m until the tank was next to empty, the ascend slowly to the surface until it actually ran out.

We must have stayed at 5m for 15 minutes or more – long enough for us both to calm down and have a look around. And to look up…

We had gone down in sunshine on a lovely blue-sky day, when we finally surfaced, it was grey, raining, we were about a kilometre from where we should have been and we couldn’t see the boat.

As the wind was already quite strong, the waves were going straight in our faces and we were kicking to stay up. There was just enough air to inflate my BC about half way before the trusty tank was finally exhausted, but we tried to use it on my buddy’s air horn to attract attention, which managed a plaintive fart that you’d not have been able to hear in church.

All told, we were actually in almost as much danger as we had been underwater, this storm was just starting to kick in, we were both tired, scared and as completely invisible to the boat as the boat was to us.

We managed to manually inflate our BC’s, so at least we could float. Taking stock, I couldn’t believe that so much could go wrong – bad weather, dive plan completely out the window, worried about DCS, no air left, no whistle, no sausage….HANG ON A MINUTE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

By pure chance, I had found a sausage on the bottom during the previous day’s dive. No-one had claimed it, so I’d stashed it in the BC pocket and it was still there! WOOHOO!!!

Using the last dregs from the tank plus a couple of breaths from both of us, we got the thing inflated and within 5-10 mins, we were on a boat with an oxygen tank taking turns, shivering and shaky, but safe and heading back to the bar for a hot chocolate with just a little brandy in it – don’t knock it ‘till you’ve tried it…

Anyway, through luck and a bit of level-headedness we both made it alright. I still dive regularly and will be taking my diving to Trimix next month. My buddy and I haven’t seen each other for a while, and I get the feeling that he doesn’t dive much anymore.

Funny thing is that I still think he’s a great buddy – one of the best I’ve dived with. What’s more is that we were together when everything seemed to go wrong and he never panicked, not for a moment. I’d dive with him again tomorrow.
 
Sounds like quite a ride - the fun part, and the not-so-fun climax. You too were on 32% Nitrox when you got pulled down to 175? I dropped deeper than intended on a wall two weeks ago - on 28% Nitrox, narced at 175 when I finally realized my goof, and I know what my computer said then, so I can imagine what yours registered. While I know that brief high PPO exposures up to 2.0 are possible, I didn't have to fight a down current to correct mine - which could have increased the possibility of a OxTox hit. Whew!

I am yet curious about this part...
Not quite sure what our best course was, we went with my buddy’s suggestion to stay at 5m until the tank was next to empty, the ascend slowly to the surface until it actually ran out.

We must have stayed at 5m for 15 minutes or more – long enough for us both to calm down and have a look around. And to look up…

We had gone down in sunshine on a lovely blue-sky day, when we finally surfaced, it was grey, raining, we were about a kilometre from where we should have been and we couldn’t see the boat.
I suppose that you were concerned about your extreme depth and fast ascent leaving you both open to DCS possibilities? But this still seems like a very long Safety Stop - to the extent of not saving any air reserve? Do you remember what your Nitrogen loads were? Again, my experience did not include a down current, so I was able to do my deep stops and 5 minute safety stop comfortably - finally exiting the water with both computers well in the Green.

The reason I ask is that in a fast drift dive, my Dive Alert whistle become even more important to me, and even with the wild experiences you endured, I think I would have been mindful of saving 100 psi to blow the horn if needed on surface - even without the surprise of the weather changing, which is still always a risk. (That happened to me on a night dive week before last, too, but the boat sounded recall and we all beat the storm out.)

I am glad you two handled the surprises well and survived unhurt. Hope you both now carry sausages. I am not known for a safe diving attitude at all, (too much cowboy in my blood maybe?) altho I keep trying to reinforce that in myself, but I always carry a sausage, a Dive Alert Horn, a Storm Whistle in case I do lose air pressure, and encourage anyone ever going to sea to carry a sausage and storm whistle.

Thanks for sharing with us here...
 
It sounds as though you got lucky in finding that safety sausage. I use a whistle and a safety sausage as well having a lift bag that I shoot for the boat to see me during the deco.

I would rather use nearly all of my gas on the safety stop/deco if I can't do a proper deco than worry about using my gas for a whistle. I can manually inflate my BC if need be, the lift bag was shot from under the water already and the other measures that I have require nothing more than my breath.

Sounds like a scary situation to me. I am glad that you made it back to 1 ATA.
 
I'd certainly agree with that...
I would rather use nearly all of my gas on the safety stop/deco if I can't do a proper deco than worry about using my gas for a whistle.
But given that his buddy is a bit of an air hog, they were on Nitrox, and on a drift dive, I'd not expect a deco obligation - which is why I asked about his puter readings, yet I would expect to be away from the boat.

I'll look forward to his response when he comes online in his time zone.
 
Wow!!!

Great story and glad your OK.

What mix were you using? did your eyes twitch from High PO2?

What did your dive computer say during this trip? Did you meet the Deco obligations it presented you? Can you download and post the dive profile from it?

Again glad you two are ok.
 
A few details - 32% mix, no deco stop was intended. The 5 minute safety stop is a feature that was drilled into me purely as an additional safety measure. Both our computers were ordinary Alladins - I know, I know, but this was early days for recretaional Nitrox, and we went by plan rather than computer.

If there is a fault with diving development in Asia, it's that you tend to over-rely on the dive guide, who often is / has been your instructor and who carries all the gear. Lesson learnt there methinks. Always have, and know, your own safety equipment.

Lastly, did my eyes twitch - can't really say, but my sphincter certainly did!
 
thepurplehammerhead:
A few details - 32% mix, no deco stop was intended. The 5 minute safety stop is a feature that was drilled into me purely as an additional safety measure. Both our computers were ordinary Alladins - I know, I know, but this was early days for recretaional Nitrox, and we went by plan rather than computer.
The 5 minute stop is universally accepted, I think, but I guess you had a typo in your first post above that cofused me a little: "We must have stayed at 5m for 15 minutes or more – long enough for us both to calm down and have a look around. And to look up…"

I'm not trying to argue with you here. Just clarifying some details for a better understanding of what you survived.

If there is a fault with diving development in Asia, it's that you tend to over-rely on the dive guide, who often is / has been your instructor and who carries all the gear. Lesson learnt there methinks. Always have, and know, your own safety equipment.
Many do, indeed.

Lastly, did my eyes twitch - can't really say, but my sphincter certainly did!
I'll bet. :) Glad you handled it as well as you did. Your brief dip to 175 feet on 32% Nitrox may have taken you to 2.0 PPO briefly, but your very short time there apparently prevented an OxTox hit. This article and this DAN article may be beneficial for more information along those lines.
 
even on a short exposure to ppO2 > 2.0 you could tox and die, and every day you'll be running a different risk. one day it might take you an hour to tox and another day just a few minutes.
 
Glad you survived to tell the tale. It serves to remind us how rapidly dives can evolve from fun to downright dangerous. Did you recollect any sense (squeeze, loss of light) that you were being carried into the depths? Did you ditch weights at the surface? I always am concerned that I'll forget this simple maneuver for maintaining positive buoyancy in the midst of an emergency, so I remind myself to remember this before every dive.
 
slingshot:
.... Did you ditch weights at the surface? I always am concerned that I'll forget this simple maneuver for maintaining positive buoyancy ....

Hey, that's $40 worth of lead. Their going to have to pry that off my cold dead body on the bottom. No way I'm dropping my lead. ;-]
 

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