Saturday, November 17, 2012

Still Alive, almost a Divemaster

Life has been flying by in Thailand. I'm almost falling asleep as I write this post because I just got off another 3-day liveaboard trip to the Similan Islands.

Before the liveaboard, we spent 4 days going over dive physics to make sure we understand the importance and justification for using dive tables and dive theory. It's pretty simple - for every 10 meters, the weight of water is equal to an additional atmosphere (atm) of pressure on our bodies. That changes how we process gases, because they are pushed from our bloodstrem into our tissues as we dive deeper, and then reform bubbles as we go to the surface. Big bubbles = bad news, since it can stop circulation! The basic rule of thumb is the air pressure we feel at sea level is doubled when we go just 10 meters down, as pressure goes from 1 to 2 atmospheres. At 20 meters, we are at 3 atmospheres, and so on.

Our bodies absorb and release gases differently at pressure, and the two main components of gas (oxygen and nitrogen) can both have negative impacts when we reach physiological thresholds. For example, nitrogen levels around 30 meters (4 atmospheres of pressure) can be so high that we get nitrogen narcosis, or "narked." I haven't had this experience yet, but I've heard it's pretty wild.  And dangerous, because it makes it difficult to focus on your dive computer (to check your depth or dive time) and it can make you want to give fish your regulator.  Not good. Oxygen also increases its potency at depth and can cause oxygen toxicity, which leads to a number of unpleasant things like twitches, visual disturbances, and possibly seizures.

And that's why we get certified and take lots of precautions! I consider myself well warned. All in all, it was surprisingly interesting and a nice refresher on basic diving physics.

We then hopped on our 3rd liveaboard trip to the Similan Islands. I actually led 2 dives of paying guests - egads! It was great! An instructor was always shadowing to make sure we didn't do anything horrendous, but it was great to be able to give a dive briefing and then lead people around a new site. I saw turtles, lots of octopus, a Napoleon wrasse, and lots more. I could only take my photo on the night dive, so here are the few decent photos from the dive and some from the boat too. One of the guests, Gian, took all the non-underwater photos.

Ghost shrimp! SO COOL
Koh Bon, one of the great dive sites we visit!
Porcupinefish! I had to take this upside down...
Rainbow after an early morning shower. Gorgeous!
Sunset at Similan Island 8 
It's beautiful here and I only have one week left of the course. CRAZY! We're building an artificial reef over the next two days to sink near Khao Lak and hopefully help rebuild the reefs. I'm not convinced we're going to do a scientifically-advanced job, but we'll learn a lot and it's awesome to be part of the project. More later!

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