Nov 102012

It’s been an interesting experience coming back to diving after a ten year absence. As you might imagine there’s been a few changes. For those of you who can’t remember, or weren’t diving then, there is one obvious change: Everyone used to dive with one cylinder!

If you did have a twin-set (and any sign of shiny D-rings on you’re stab jacket) then you were most definitely a “technical diver” – a term very much in it’s infancy then, and as far as I can tell, no more strictly defined now. But very few people did “twin up”, and fewer still really saw the need to. For those that did want for some extra security in terms of a completely separate system, a 3ltr pony cylinder was adorned – not for breathing on every dive, but simply there for emergencies.

I was an early adopters of twin cylinders. Actually, being a student, it was all mainly club equipment: the only bit that was mine were the twinning bands! For me, the twin cylinders were simply a way to carry more gas, and were only used for dives over about 45m deep. I suspect that there is something that might upset a few “modern” divers here: the technology was there to carry fully redundant systems and people themselves were no less intelligent or well educated than they are now, but they carried only one cylinder – one cylinder that could fail and kill them… couldn’t it?

As I see it, there is a great paradox in modern diving. One school preaches carrying more redundancy (which by definition increases complexity and failure points, but does provide more redundancy), and the other preaches on the simplification of kit (less points of failure with kit or the diver adorning it, but no on-board redundancy). These philosophies are in conflict. The outcome of these tussles seem to have settled with the modern ‘basic’ kit consisting of a twin set.

4 cylinder setup

Mini-Quad: My current setup mainly used for 35 to 50m dives

But why do we need to carry a twin set for a 20m dive? With a single cylinder we DO have redundancy – it’s called the “Buddy System”. By keeping with the simplest set of kit we reduce our chance of having any sort of equipment failure lead incident. By diving the buddy system, we ensure that if there is a failure, a truly completely redundant system is available. The argument against this is that you’re buddy might not actually be there to help when there is an issue, but to a large extent is this an issue with modern diving technique? Divers who only ever knew diving on one cylinder tended to dive the buddy system strictly. The so called security of a twin set can result in dive practice that places less emphasis on diving with a buddy, and more reliance on extra equipment, and let’s face it, there are multiple equipment induced fatalities every year. The thing is, when it all goes seriously pear shape, is it extra equipment you’ll be hankering after or a sane buddy to calm the situation down, help sort the problem out and make sure you get back to where the air is free and limitless?

So obviously I dive a single cylinder on everything but deep dives right? Ahem… well actually I’m twinned up most of the time (bloody hypocrite I hear you all cry). My excuse? I don’t have a single cylinder to dive on! :-)