Tuesday, April 15, 2008

Cave Skills Part 3 - Gas Management (Part 2)

The basics of gas management dictate that you always have sufficient gas in order to exit the cave and complete your required decompression. It sounds a whole lot simpler than it actually is because there is no iron clad rule that says this is sufficient gas. As a community we agree that you should be carrying at least two thirds more gas than you require to get in (i.e. your deepest point or the end of your planned bottom time) but that does not always provide enough gas and certainly does not do the job when you are looking at a complex plan that uses multiple gases. My previous blog addressed the concepts that I use to calculate sufficient gas and as you can see, even in that there are some ‘loose’ areas, areas where I working on assumptions and so increasing my risk to the point where getting out is more luck than planning. However, I understand when I am entering this zone and I have options to avoid it. Accepting additional, non-controllable risk is an option I give myself. It is a choice.

There are other choices to make when planning your gas. Aside from the thorny issue of how much is enough, there is the strategy you use to supply that gas. Most gas management strategies view the dive team as a single entity and distribute the bail out gas amongst the team. They assume that an incident will affect one person only, leaving at least one (if not two) additional team members to assist. They also assume that the team will always be together so the gas is always available when needed. These are all assumptions that I am personally very uncomfortable with because I am having to place my life in the hands of another person. I guess it boils down to the fact that I simply do not believe that your buddy is someone you can trust your life to. Things happen on dives.

What if the team splits up and you now do not have all the planned bail out gas ? What if two divers are in trouble ? What if the divers are unable to get their stress under control and as a result that well laid plan is completely irrelevant and you are now in a situation where it does not matter how little you are breathing, your buddy is munching gas at a rate of knots ?

It is not that I am saying that I dive with unreliable people, I do not! But there are just some responsibilities you do not hand to people you love and respect. I do not want the people I dive with to have to live with the niggling doubt that they some how were responsible for my death. If for reasons beyond their control they were not where they were supposed to be and as a result I did not have the extra gas I planned on and I die, well that is not a burden I want to give people I care about. Things happen on dives. Things that are beyond an individual’s control. The only life I am responsible for underwater is my own. If I see someone in trouble I will still attempt to help, but I am not sure I would be willing to place my life on the line. Maybe I will, maybe I won’t. I don’t know, not until I am there. Is that uncertainty something you want to trust your life to ?

As a result, I believe that dive teams should plan dives as if each member of the team is diving solo. No diver should count on using his buddies gas to get out in an emergency (it is there, but not part of the plan). This is far safer and far more reliable an option, even if it does require more planning. Some may argue that it adds an element of complexity to the dive, after all if you have a three member team doing a deep penetration you now have to have three times the kit all of which has to be staged in the same place, creating clutter and possible problems when divers all try and get to their gas at the same time. My answer is perhaps, but those are predictable and therefore solve’able problems. You can change the process - each diver can stage in a slightly different place to avoid congestion. The worst thing that can happen is that one or two of the divers are late on their plan…alive but late. Not having the gas because your buddy never made it is a situation that is unsolve’able, especially underwater.

There are plenty of decisions like this in the world of extreme exploration and it is easy to get bogged down in which way is right and which wrong. There is no right and wrong way, only different sets of risks, different sets of probabilities. As a diver you need to understand all sids of the story and choose what fits you. If in doubt, there is one rule that makes decisions simple, find out which option will definitely kill you if you encounter it, and choose the other option, If you don’t’ like the other option, you should be choosing not to do the dive.