GREAT BARRIER REEF 2012 - PART 5 - NORTH HORN WALL

And time flies…

 

It’s a new year, and over two months since my Great Barrier Reef trip. I figure I should pull my finger out and finish this story... I started writing this post with the intention of summarising the rest of the trip, but got stuck on this one, special dive…

 

GREAT BARRIER REEF 2012 – PART 5 – NORTH HORN WALL

North Horn Wall – Deep Dive

TRIMIX COURSE - PART 2

I am a Trimix diver.

Wow, what a course.  Everyone asks me if I had fun… the thing is... I’m not sure I did! 

Although I finished a few days ago, it’s taken me this long to get my head sorted out.  This was easily the most challenging course I’ve ever done, and because of this, the most rewarding.  I thrive on a challenge, so I certainly enjoyed myself, but ‘fun’ never entered into it.

I went into the course expecting to go beyond my comfort zone.  At this level of diving, the course is as much about testing the diver’s mental abilities as physical skills.  Task-loading and simulated problems add to the stress level and test the diver’s ability to cope.  I knew all this, and at times still found myself questioning whether I should be there. 

In many ways, we are our own harshest critics.  It was only when I reminded myself that I did achieve what was asked, that I felt better.

 

DIVE 1 45M TRIMIX 18/35

THE TITANIC AND AVOIDING THE EVIL TWINS

Just seven days to go until the start of my Trimix cert course…  I just realised it will be the day after the 100^th anniversary of Titanic’s sinking.  I’ll use my wreck fascination to interpret this as a good omen!

My spare time is full of revision… gas laws, deco schedules, emergency procedures… oxygen toxicity, nitrogen narcosis, decompression illness…  And the abbreviations: EAD, HPNS, OTU…alphabet soup for divers.  It’s all come back, but it needed work.

I’m planning numerous dive scenarios, considering gas mixes, calculating oxygen exposures and allowing for contingencies.  I usually do all this stuff with a spreadsheet and software, but I find running through longhand brings it to the front of my mind.

I still enjoy ‘playing’ with dive plans, which is a good thing… it’s not unusual for planning of a technical dive to take longer than the dive! 

Warning - the theory that follows is a bit dry…

IDEAL GAS MIX, OXYGEN TOXICITY, EQUIVALENT AIR DEPTH

Avoiding deep-diving’s evil twins, oxygen toxicity and nitrogen narcosis, is the whole point of Trimix.

What is this Voodoo Gas Called Trimix?

Trimix is a mixture of helium, oxygen and nitrogen.  Divers use Trimix for deep diving to depths where the effect of nitrogen narcosis is no longer acceptable and normal oxygen concentrations are toxic.

Air is mostly nitrogen (78%) and oxygen (21%).  Humans don’t use any of the nitrogen we breathe; biologically speaking, it’s an inert gas.  We need oxygen to live, but at high pressures, it causes seizures and unconsciousness.