DIVE LOG Australasia

“My boyfriend is doing a nitrox course. Should I do the course with him? I don’t need it as I always have at least 100Bar left in my tank at the end of a dive when he is down to 30 Bar.” What I took away from this, and several of the replies, was that many people have an incomplete concept of nitrox and why people choose to dive with it. I also guessed they might not be alone and that there may be widespread confusion over nitrox, what it is, what it does and what it doesn’t do. So, I thought I’d clarify things a little. Benefits The primary benefit of diving with nitrox rather than air is that, with nitrox, you breathe less nitrogen than when you breathe air. Assuming that the nitrox you are breathing is nitrox 32, which it usually is, then 68% of each nitrox breath you take is nitrogen rather than 79% of each breath of air – and 32% is oxygen. This means that the nitrogen level in your body builds up more slowly during a nitrox dive than during an air dive. Therefore, if you are using nitrox AND if your computer is set to nitrox, it will take longer for you to arrive at your no decompression limit than if you were breathing air. If you are typically doing dives on air where your dive time is limited by your no decompression limit Why should I do a nitrox course? S ometimes, even a seemingly minor comment on social media can generate a magazine article or even a whole book chapter. That was the case with this query that I recently saw posted in a divers’ chat room. 1.

rather than your air supply – that is, you are coming up from your dive with plenty of air left because your computer is showing that you are about to go into deco - then using nitrox will give you longer dives. Having said this, of course, if you are typically ending your dives when you run low on air and still have plenty of no decompression time remaining, then switching to nitrox will make no difference at all to how long your dive lasts. This is because using nitrox instead of air does not affect how quickly you use up your breathing gas. There are plenty of techniques that WILL help you reduce your consumption rate, but that is a separate discussion. ( My Scuba Confidential book has a whole chapter on it.) But should you still do a nitrox course even if you are a new-ish diver? Yes, you should, because you will not always be new-ish, and you should be prepared for the things that will happen as you become more experienced, such as: You will find you no longer use your breathing gas up as fast as you did in the beginning, and you will also start doing deeper and more challenging dives. To give you more no decompression time on these dives, you will need nitrox.

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DIVE LOG Australasia #408 - October ‘24

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