On the boat, Kenny and I were both Nitrox certified. The course cost was $150, and involved a few hours of theory and two dives on Nitrox. Additional Nitrox tanks were available for $10 a dive, or $200 for the entire week. Nitrox is air with additional oxygen mixed in. Normal air is approximately 21% oxygen and 79% nitrogen. Nitrox mixes contain more than 21% oxygen (typically 32% and 36%, in recreational diving), so when you are at depth you absorb less nitrogen. Less nitrogen means a smaller chance of getting decompression illness and longer bottom times (but a shallower maximum depth).
Anyway, the theory was a piece of cake. Anyone who has studied how gases behave under pressure in high school physics should take about five minutes to understand the theory behind Nitrox. Diving with Nitrox involves a single added calculation. Anyone who can't understand for whatever reason can blindly dive using the tables and formulae supplied (hmm.. I'm not sure if that's a good idea or not, though). The PADI course video and course materials are designed for people who have not taken physics and are almost painful to sit through. However, I did forget one aspect of using dive tables, since I use a dive computer, so the course was useful as a refresher.
After getting Nitrox certified, I did a single intro dive using a Drager Atlantis Semi-Closed Rebreather. It uses a scrubber to remove carbon dioxide and recirculates exhaled air, using a small Nitrox 40%-60% (air containing 40-60% oxygen) cylinder to replenish depleted oxygen. It was fun, but made bouyancy control more difficult, because a counter-lung holds any air expelled from one's lungs. This means you can't use your lungs for bouyancy control when diving with a semi-closed rebreather. It was quiet, though.
Matt kept telling us about some guy who blew his hand off while opening the
airflow of a Nitrox tank on a routine dive. I know you have to be careful while
filling Nitrox tanks because the method often involves handling 100% oxygen,
but I don't believe him. He's a big joker. :)
[next - people]
) bond, setting up rebreather |
) the drager atlantis |
) ... completely set up |
) doing a little theory |