Nitrox, Dive More or Dive Safer, Sea Surveyor, Red Sea

Waterlogged Date: 7/9/97

The MV Sea Surveyor was the first liveaboard in the world to have Nitrox facilities and instruction available on board. Although I had not planned to try Nitrox anytime soon, it was an appropriate time. It seems more logical to me to take courses and learn under real diving conditions than at home in a pool or lake. The Red Sea diving we were doing was relatively shallow, no deeper than 30M or 100ft. As I learned in the course, the depth limitation of a Nitrox mix is really the only handicap involved. We were doing 4 or 5 dives per day for 10 diving days and I was taking photos. Ideal conditions for Nitrox. A little extra bottom time and a little extra safety couldn't hurt. I was curious to see if the claims that diving on Nitrox would be less tiring and physically easier than diving with compressed air were true. David Hillel, captain of Sea Surveyor and our instructor, had been a commercial diver, diving mixed gases for years. He has certified more than 3000 students and really knows his stuff, from experience, not only from books and pool sessions. Chris Herrmannsen, a South African living in London, and I started by reading our ANDI (American Nitrox Divers International) materials. For the most part, the course described the physiological effect of breathing increased levels of oxygen on the body, taught us to use tables for various standard mixes of Nitrox (defined as any mix of nitrogen and oxygen with oxygen between 21-50% of the mix) andto calculate formulas to use non-standard mixes and switch between mixtures and compressed air. We intermixed our reading with lectures from David and our usual 4-5 compressed air dives per day until we reached the open water part of the course. After 6 days of diving compressed air I did notice a difference, even before I got in the water. The 32% O2 Nitrox mix I used tasted fresher, probably due to the extra banks of filters in the Sea Surveyor's blending system. The filters must be used to purify the compressed air to remove any traces of oil and other substances that might combine with the elevated level of oxygen in the mix and have a harmful effect on people and equipment. Yellow and green nitrox cylinders on our backs, Chris and I began our first dive on Nitrox. Chris, who celebrated his 100'th dive on our trip, immediately found the Nitrox to be much better, giving him the strength to push on through a strong current as we rounded a point at Elphinstone heavily laden with soft corals that bent toward us. I actually didn't notice this effect, being too intent on capturing the corals on film. During the dive I didn't feel any different than usual. 2000+ dives make me quite relaxed underwater and ducking the current, taking the easy route, has become second nature. I assume the difference would be more noticeable to less experienced divers. The true test for me was at the end of the day. I did still feel a bit tired (who wouldn't after 6 days of non-stop diving and eating), but not to the extent as on the previous days. I even managed to stay awake after a night dive and dinner to read my ANDI book! The tables and formulas in the course were a bit daunting, but required pretty much the same talent as a standard open water diving course. My next purchase will be a combination Nitrox/air dive computer so that I can reap the benefits of higher O2 without all the fuss. The question remains: Dive more or dive safer? Nitrox gives me a choice to follow my air computer and greatly reduce my risk of DCS as I did on this trip. Or I can use a Nitrox computer to extend my bottom time and reduce surface intervals. Either choice will conserve my strength for photo editing and writing in the evenings following a full day of diving! For information on the Sea Surveyor's Nitrox instruction and diving contact Sea Surveyor. To book a trip on the Sea Surveyor contact Dive Discovery. Story by Deb Fugitt.

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