4 Ways to absorb nitrox
TDI Nitrox Diver
The classroom for my first course was afloat - the saloon of the mv Nouran, in the Red Sea. I was on a live-aboard safari north of Hurghada organised by Diving World, and the course was devised by Technical Diving International (TDI) Middle East.
We had a potential of four dives a day, a fresh February breeze from the north, and a 70-page Nitrox Diver Manual to digest and understand. This looked like being a challenging week, mentally and physically, for me and for fellow-student Vicky Steddall, who was training to become a divemaster.
Our instructor Ali Mahmoud Ali El Azaizi, better known as Ali Baba, put the week in perspective for us and for his eight non-nitrox students, some of whom were fairly inexperienced. "It's all in your head," said Ali, starting to work his familiar magic. The guests visibly relaxed.
We were out on a live-aboard to maximise the diving potential, with the course squeezed in between dives. We started at Um Gammar, then continued to the Ghiannis D, the easiest of the wrecks at Abu Nuhas, and a lovely night dive on the Barge at Bluff Point. With water at 24*C and air at 20*C, this was cool for Egypt but a world away from the English winter.
After supper we began the course, which teaches the use of nitrox mixes to a maximum depth of 40m. After some four hours' total tuition, one hour each day, we would have to score at least 75 per cent in an examination and analyse the mixes for the first two dives to qualify as basic-level TDI Nitrox Divers.
In essence, it's simple: "breathing continuously, knowing how to work a dive table, analysing your cylinder's oxygen content and not diving beyond the limits," says the TDI manual.
We began with a refresher: what is air, what is nitrox, advantages and disadvantages. Clearly nitrox provides more options than air in the 18-40m depth range, below which oxygen toxicity becomes a major factor. We were surprised to learn that nitrox was first used as early as 1794 and dived with in 1879 - so much for the popular conception that boosting oxygen levels in air is a recent development.
The next day we dived the Thistlegorm three times, the third dive being particularly memorable for a rapid deterioration in the weather while we were under water. A broken shotline, a lost weightbelt and a masterful control of a difficult ascent by Ali Baba, in which he had to hold six divers together, fuelled the post-dive briefing.
I skipped the night dive, trying to save some energy for "Diving Physics Made Easy" and the "Equivalent Air Depth Concept". These chapters are the backbone of the course, but too much for one evening after a tough day on the Thistlegorm. Dalton's Diamond failed to glitter, while new terminology for me and some less-than-clear text in the second chapter made for two tired and rather bemused students.
Next day's close encounter with a whitetip reef shark at Bluff Point provided a stimulating antidote to the classroom. In the evening we covered the final topic - use of oxygen analysis equipment. This, as I would later find out, varies very little between courses.
Our examination was taken the following day at 9pm, after two dives at Gobal Island. Like many diving exams, this is primarily a multiple-choice (or multiple-guess!) test, so favours those who are good at exams and can work out what the examiner meant to ask rather than what was actually asked.
In some cases, identifying the least wrong answer was the way to find the correct one.
It was difficult to concentrate with the hubbub of divers relaxing around us. Ali trod a difficult path between keeping them quiet and keeping them happy.
But we both achieved a good pass and after analysing/planning our next two nitrox dives we were qualified to dive on up to 40 per cent nitrox for no-decompression-stop dives.
Ali Baba made us work hard for the answers, which were often not found by slavish use of the tables but "in our heads". Because he is deaf, Ali's speech requires concentration, which no doubt increased our learning dramatically.
Vicky and I did five more nitrox dives, mostly around the fascinating wrecks of Abu Nuhas. Whether it was the nitrox or the placebo effect, I don't know, but we felt less tired, even though there was more planning and preparation to do.
Like all good instructors Ali Baba stressed that the qualification was only the beginning; we must now practice using nitrox to make the most of it and stay safe. He recommends at least 10 practice dives. There is also an advanced TDI course.
I found this a very pleasant way to do the course, combining it with some excellent diving on a comfortable live-aboard. Ali Baba was a wicked tease to all of us; little escaped his eagle eye. The crew were helpful and good fun; the food was excellent.
Appeared in DIVER - July 1999