Zero Viz air share
I know we have all done this in our Cave classes. However, I was thinking about the practicality of this situation today. But assuming no stages or no scooters would you not be pretty much screwed if you were in this scenario? I suppose if it were for the last few hundred feet maybe until you make it to your deco bottle
As you will be moving very slowly in the zero visibility and SAC will be elevated, seems to me the better option. Would be get yourself out
Of course that is an option to get yourself out, but at what cost? There certainly are some ethical dilemmas (and possibly even legal) in making the decision to leave a buddy ,or worse a friend, to painful death. Worst case scenario would be a failure at max penetration or at thirds (based on diver with highest rmv) diving OC. The only hope is if both you and your buddy keep a calm mind and have the experience to safely follow the line back to your staged gas. This is just one more reason to always dive conservatively well within your limits and ALWAYS treat the cave environment with the respect it deserves.
This is why you always need to consider the 1/3th rule. And if it really happens, most times more things went wrong before you came in a no gas-no viz situation.
But of course there are possibilities such things can happen. A cave with dark old lines, and lots of perculation. Then you loose the line, have to find it back in no viz and then exit. If you are in a team of 2 and both loose the line, it takes time to find line back and try to stay together, it costs gas, and maybe the rmv will be higher due to stress, if this happens on the turnpressure of 1/3th, you will need your reserves, depending on time it takes and stress, maybe one will run out of gas, then share, but in worse case, the other diver has not a lot of gas left too, then go out till you find the deco bottle. The unwritten rule better 1 dead and 1 alive than 2 dead is difficult. If you ever have been in such a situation, will you share or kick your buddy and friend away? I think this is an question you never can answer before you have been in such a situation. And even then it depends on the situation. With good planning, taking care of each other, treat caves with respect, and hope bad luck will never bring you in such situation. But stop and wait till you die is never an option. Always try to find a way out.
I have been in a situation of let die or die both. I have had such a choice when I was a sportsdiver, it has been one of the reasons to start cavediving. It was grouppressure. I went to a wreck on the Northsea, I still like wreckdiving there. I was at that time Divemaster, and had 249 dives (it happened on my 250th dive). I had decided that it was time to move on to technical diving, so I had a twinset and wing, but was diving my 18liter single tanke here and wetsuit. I did not had any technical diving experience then. My buddy was an sportsdiving and wreckdiving instructor with over 1000 dives, he dove an double 8.5 liter twinset with wetsuit. Most times we dove solo on the wrecks, but this time we decided to dive together. We wanted to take a reel to find the anchor line back (viz can be bad), but others said no, don't take it, all that lines will mess it up and make it more dangerous. I don't know why, but we decided not to take a reel as we did not have plans to penetrate the wreck. We just wanted to look for fish. So then we went down, the viz was bad, 1m/3ft, we swam around the wreck over the sandy bottom and there was lots of small fish and critters in the sand. And then, we where in the wreck without notice. No panic, just find the way out. We swam hand by hand and made siltouts. But no exit came. Then my computer beeped I was in deco, NDL gone. No panic, I was just thinking if I come out on my last air, they will bring me in a chamber and all will be fine. But then we swam and swam, I could hear my buddy was in panic, breathing really fast. I calculated that if I do not came out, I will be death in 20 minutes. Then I started thinking, will I share air or kick my buddy away? I knew he will run out of air before I will run out of air. The idea of 1 dead better than 2 dead was in my brain. But then the moment came. Without thinking I shared air, maybe the worst choice at that moment, but I did. And we found the exit. I don't know why I stayed calm, but I knew I can handle it to surface, I took time to shoot an smb because of current and no time to reach the anchor line, and I did the stops according to my computer while sharing air with an octopus. We surfaced with 10 bars left in my tank. I have talked to my buddy after this, he said he could only think 1 thing: I am instructor, have 4 times more dives than Germie, why did I listen to other divers not to take a reel? He could not think or relax he said. We dove the next day again. I still like wreckdiving (always with reel), my buddy almost quit wreckdiving since then. He said it has nothing to do with what happened then, but we all think it has. From 2 times a month wreckdiving to only 2 times in years. I don't do it 2 times a month anymore, but when I have time I go. And when I think I need such gear or tools I will take it even if everybody will say no need to take it. In my example we made mistakes by listening to others, grouppressure. But we both reacted different on the situation.
So different situation, but gassharing in zero viz.
That type of scenario validates why the rule of 1/3rds is overly liberal, and why something else should become the gold standard. Air sharing at max penetration on 1/3rds will probably not guarantee an exit,but if we add zero visibility, it guarantees there are two victims. We don't dive raw Buhlman's because we know we'd probably get bent, so we add conservatism with things like gradient factors etc. Computing our gas for 1/3rds during an S drill in the water is like diving raw Buhlman's, we need something better.Originally Posted by Germie
"Not all change is improvement...but all improvement is change" Donald Berwick
I use the 1/3 rule as a minimum. I add to turnaround for things like a new buddy, a site I have never dived before, silt, and of course a syphon.
Exactly.
And there are caves with good viz in and low viz out.
Yeah but the very common thing is to dive full thirds, personally I dive thirds but always carry a stage the whole dive buddy or not, never used in gas planning, I've gotten so used to a stage it doesn't slow me down
And I practice if I have to start sharing gas, that I donate my long house and switch to my stage, I would not like to have a buddy go OOA twice
You could just hand him the stage, then there is less chance of getting tangled in the line from being connected by a hose.
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