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

CONVICT RUINS AND EXPENSIVE BUBBLES - TRIMIX COURSE - PART 3

It’s taken me a few weeks to finish this, but here it is: the final instalment of my Trimix course report. 

Last weekend I did two days of solid diving, including putting much of what I learned into action.  But, I’ll tell you about that weekend, later... for now, enjoy!

In case you missed them:

Trimix Course Part 1

Trimix Course Part 2

TRIMIX COURSE - PART 3

DAY 1 (CONT.) 

Our Day 1 dives were done, but the day was far from over.  We were in for a fine session of gas mixing and dive planning, not to mention Rubens’s critique of our

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.