People seem to be failing to make a distinction between out of air and low on air. To me, low on air means it is starting to get hard to breath. Most divers, if they are neutrally bouyant and not totally out of breath should be able to easily and immediately rise to the surface, modulating the air in the BC and minimizing effort and kicking. They should be able to sip multiple breaths on the way up.
On the other hand, if a diver should be working on the bottom and be negatively buoyant, and they crawl under a ledge to catch a lobster or something and they rip off a LP hose or dislodge the first stage yoke from the tank (due to low pressure), they will be presented with a much. much more serious problem. ( A bad free-flow when the tank is low could also approximate this situation). The diver now has no way to inflate the BC, absolutely nothing to breath and some people like to dive with zero ditchable lead now. If they are at all out of breath during this incident, then kicking up 100 feet is NOT GOING TO BE EASY!
I find all this talk of 90 ft free ascents (e.g. Dan Volker) to be almost completely irrelevant. Who cares what he thinks he can do in an emergency? Most people can not freedive to 100 feet and most people can not kick up safely from 100 feet when negative with zero air. It needs to be taught because it is the last ditch answer (plus it should work from really shallow water) but it is NOT a practical solution to total loss of air at depth.
For me, redundancy below 60 feet is the only practical answer for a majority of the recreational divers. That is how I dive, almost always.
DD,
First, spearfisherman and lobster divers are NOT supposed to be part of the NOVICE OOA diver equation....if you or I are doing either one of these behaviors, we have many issues going on a new diver would be crazy to consider dealing with.
I would not want to see the novice diver negative on the bottom. They should be learning perfect trim and perfect bouyancy, so they are dead neutral at depth, and once they ascend 20 feet they are beginning to accelerate by increased lift from the bc.
As to an advanced hunter runing OOA at depths like 90 or 100 feet, if they have freedive skills ( good for any hunter to have), then this is still a non issue. For me, free ascending from 90 feet would not require even one breath, as the air in my lungs will have my lungs filling soon enough, and the surface is only a few seconds away....in perspective, I think it is fair to say that going off the bottom at 90 feet with no breath, is about equivalent to diving down 25 feet with a full breath from the surface. If you were in a full max effort, breathing at 100% of your ventilation potential, then it may be touch and go....but this means you have made so many big mistakes in a row, you would expect Darwin to be watching you in 1080P.
You would have your pony bottle and necklace reg. I would have a buddy, and we would both know the air issue ensuing--proactive measure should already be in play.
The beginner -- basic open water diver...should not be deeper than 60 feet. They should not be negative at depth. They should have practiced free ascending enough to know this is incredibly easy....I would compare a 60 foot free ascent on zero breaths to going from the surface down to maybe 12 feet deep on one full breath, and then back up of course....there is nothing to it, unless panic sets in from never having practiced the skill, and not knowing if you can reach the surface.
Here is a story from my early diving days, of a pretty serious OOA event
This occured back in 1976. I was on a Marine Research trip to Tobago with New England College. The professor leading the group, Taylor Loop, was an ex-navy frogman, in addition to having a PhD in Geology.
I was a freshman on this big research trip, allowed to be there because I had convinced Taylor that whenever one of his wimpy students could not get into a harsher environment, he could have me do the dirty work....He liked that, and let me on the trip( mostly seniors and grad students).
There was one area of of Tobago's Bucco Reef, where it would appear from a plane flying overhead, that the huge 30 foot waves went around in a complete circle, around an area the size of 6 or 7 football fields in diameter...anyone caught at the surface in these huge breaking waves, would be killed...there would be no chance of not being thrashed into the coral 45 feet below, and churned, and drowned.
Inside the huge waves, in the interior, was the richest ecosystem I have ever seen, to this day. Baitfish completely obscurred your vision, permanently inside this zone...the three converging currents which created this zone, brought in marine life that was the stuff of legends.
Taylor and one guy from the village, had been the first ever to get inside a few years earlier...he had picked his way through a maze of coral channels, ultimately staying protected from the huge churn, and made it inside, where he was amazed. There trip was shortlived, as a Great White greeted them inside the zone, the other guy ( Charles I think), fed it a spear, and they both left the way they had come. The island later had the GW netted and removed by helicopter, as they were panicked this GW would destroy their ideas for tourism on the island, and Taylor had explained the shark would have no reason to leave such a huge supply of food.
I was assigned to report on the coral species and fish species on the transect we could do, from outside to inside the zone.
My buddy had a pressure gauge, I had a j valve on my steel 72. Each of us used a single 2nd stage ( no one had a spare 2nd back then). No BC was used of course.
As we went in to the churning zone, maybe 60 yards long, we would swim fast till we saw the DARKNESS coming, this being the huge wave about to go overhead. Just before it reached us, we would grab on to the bottom( largest structure nearby, with gloves), and wait for the big surge to pass over, then swim like crazy till the next dark shadow appeared. It took us about 10 minutes to get in, at an average depth at the maze/channel bottom of 50-60 feet. Once inside, we were blown away by the IMPOSSIBLE VOLUME of fish all around us. While the main reefs of Tobago had massive fish volumes back in the late 70's, you can't imagine what this was like!!
My buddy was jotting notes down on a slate.., and then checked his guage( about 5 minutes after entrance into the interior)....he should have had lots of air, but apparently, he used up a huge amount getting in to the interior, and now down to around 400 psi, we knew he would run out before we could get clear of the churning zone..the Shadow Zone ...
We both looked at each other like OH Sh*& !!!! And immediately headed out the way we had come in. We knew he would run out...the only question was when. About 1/3 of the way back through the zone of shadows, he ran out. We were staying right next to each other for this obvious eventuality. Without any hesitation, I gave him my reg, he held the back of my tank, and his job became passing the reg back and forth between him and me....My job was navigating us through the maze, no longer stopping for the shadows and churn, just swimming fast and efficiently, and fending off coral boulders as the churn would shove us forward hard at each pass.
At about two thirds of the way out, my tank got to reserve, I pulled the j valve lever, and we knew we had no chance of making it all the way to the end of the shadow and churn area....we both knew when we did run out, we would have to swim horizontally until we cleared the shadows, and could then do a free ascent.
We made it to about 70 feet or so from the well defined end of churn and shadows..with the close to 250 foot visibility, this was easy to see, even from where we were in the coral channels.
As we ran out of air, neither of us had much of a breath, but both headed horizontal for the 70 feet, until we could see no churn....then began our free ascent....Oxygen partial pressure helped the traverse, so the 70 foot run was not all that hard....as we began slanting up near the end of the run, the slight exhale felt good, but I remember really wanting to be able to breathe again soon....we were still calm, but certainly worried at the same time--this was far beyond anything we had ever practiced or done before.
I remember the last 20 feet to the surface..My legs getting weak....remember, no BC, we were doing all the work with our legs to get to the surface. At about 1 half second before I hit the surface, I felt my legs completely turn to jello. Absolutely zero power left, they would not kick any more. My inertia carried me to the surface, where I spit the reg just before broaching, and got 1 breath before my head went under again. I was somehow able to get my mouth into the surface air again, maybe by hand swimming, I don't know..we were fairly neutral in bouyancy. Both my buddy and I struggled like this on the surface for at least a few minutes, before we actually had the strength to begin swimming and put our snorkels in our mouths. My legs felt like I had just run 50 miles, and our bodies were trashed. We began slowly swimming, and within another 5 minutes, we had recovered to feeling practically normal again, as the lactic acid which had filled our legs and bodies, converted to pyruvate, the oxygen debt was paid off, and we actually began to feel pretty good.
I learned.....not to do this dive again without very different gear....I never did get the chance to do this dive again.
I would do it today with a good buddy and high pressure 100. Doubles would be so much drag you could not handle the current and surge.
I was very happy that both my buddy and I had very good skills at free ascending. The buddy skills were something we just took for granted back in those days, because this was so easy for the people that I was diving with....maybe not so much for some of the wimpier research guys, but for Taylor and his team of really good research divers, this was easy....Taylor was a huge charicter, one deserving of many stories about his exploits
REgards,
DanV
