Voodoo Gas, Nitrox, or to give it the correct name, Enriched Air Nitrox (EANx) is still a mystery to some people. Why use it, why pay for the course to learn how to use it, and what are the benefits? I found out the answers to these questions many years ago when I did my PADI EANx Course. Back then it wasn’t that common, hence the nickname ‘Voodoo Gas’.
For the uninitiated, EANx is used by divers in order to have longer dives at certain depths due to the fact that the percentage of oxygen is increased. This means that the percentage of Nitrogen is decreased, nitrogen being the limiting factor in depths and times of dives. Normal air is 21% oxygen and 79% nitrogen, whereas the two most common blends of EANx are 32% or 36% oxygen leaving only 68% and 64% nitrogen respectively.
One of my biggest questions, however, remained unanswered – ‘How do we get Nitrox into our tanks?’ – I had a rough idea but it wasn’t until I recently undertook my PADI TecRec Gas Blending Course that this was fully answered!
For the first time in a while the instructor became the student as I was handed my Gas Blending Manual and told to complete Knowledge Reviews 1,2 and 3….now don’t get me wrong but I am used to being the person asking students to give up their evenings to study, now I am being asked! Oh well, for the greater good…
The next morning I met up with Wilco, who was to be my instructor for the next couple of days, and we walked through the reviews, adding ‘meat to the bones’ where we needed so I had a full understanding of how EANx is blended and the possible hazards of the differing procedures and how we avoid them.
Next it was onto the practical side of things and actually learning to fill a cylinder with nitrox rather than normal air. Knees knocking, I followed Wilco to the compressor room and started to learn all about all the workings of the complressor and how to blend different mixtures of gases correctly – but only after a stark warning from Wilco – ‘When filling nitrox, please don’t blow up the compressor room!’ – now I am not usually a nervous individual but that got the sweat trickling down my neck, or was that the 38 degree heat?
So we worked step by step through everything from attaching the tanks to the filling whips (the hoses used to put the Nitrox into the cylinder), to startup steps for the compressor, to how we add the oxygen to the normal air to achieve the desired percentage blend and finally to the full shutdown upon the fill of all the cylinders needed.
Ten cylinders later I felt comfortable in blending Nitrox, as long as I followed Wilco’s expertly written step-by-step guide! I went on to complete the rest of the Knowledge Reviews and take the final exam…scored an 88%…not too shabby!
I have been regularly blending and filling our Nitrox cylinders since my course and am getting more comfortable each and every time. I may even be able to ditch the step-by-step guide sometime soon!
The PADI Self Reliant Diver course – so what made me decide to do this? After all, I am an instructor and dive centre manager, with not an insignificant number of dives under my belt; what else could I learn about e.g. my air consumption that I didn’t already know? As it turned out… quite a lot!
It was during a dive at Twins, one of Koh Tao’s most popular scuba diving sites, with a DM friend of mine and her Open Water certified boyfriend that the idea first came to me. My friend was, quite rightly, being the perfect buddy to her inexperienced boyfriend, and I thought “What if something happened to me right now?’ and it occurred to me that, whilst I was certainly not in any imminent danger, if I did suddenly have an equipment failure, who would be there to help me? Then I cast my mind back to when I was teaching full-time and again it struck me that as a dive professional there isn’t really anyone to look after you, should things go wrong. At that point I decided that I really did want to do this less well-known PADI course. Having done the first of the PADI Tec courses, Tec 40, a few years back, I knew from that training that you have to be prepared to end any dive and get back to the surface, no matter what the situation or the conditions, on your own. So doing the PADI Self Reliant Diver course made sense.
As soon as I got back onto the boat, I spoke to Wilco, our Tec and Self Reliant Diver instructor, and told him I wanted to do the course. “Why?” was his immediate answer; to which I carefully and knowingly responded “So I can dive alone”. Having worked with Wilco for the best part of 7 years, I knew precisely how he would react and what his next word would be: ”Wrong!” was his immediate response as I smirked cheekily at his predictability! And what Wilco said was completely correct; the premise of the Self Reliant Diver course is not so that you can simply dive alone; it is to provide you with the skills and knowledge to dive independently, whether that be leading a group of students, diving with other dive pros (let’s face it, most of us are too busy doing our own thing underwater!), or if the situation arises, diving solo, as in the case of underwater videographers and photographers. The course also makes you far more prepared as a buddy.
I managed to persuade Elaine, co-owner of Master Divers, to do the course with me – which that meant double trouble for Wilco! Whilst there is no manual for the course, we still had a Knowledge Review to complete. Calculating our Surface Air Consumption (SAC) rate was the first job. Until we did the first dive, we would have to estimate it which we did at around 12L; we then had to determine, individually, how long we were going to dive for, at what depths and how long at each depth, using several formulae (don’t worry if Maths is not your strong point – they are straightforward); we then had to work out, using our estimated SAC rate, how much air we would use during the dives. What we found after the SAC rate skills (swimming as fast as we could for 1 minute at a depth of 10m and recording our start and finish pressure) was that our SAC rates were identical at 5.5L. Even Wilco was surprised at how low they were!
There are 3 dives for the course, and for the first 2 dives, you are with your instructor, as there are a number of skills that they have to assess during the dives. Having planned the dive ahead of time, we were each allocated a dive to lead. First off was the Self Buddy Check, which is exactly the same as a normal buddy check, but you are doing on yourself. As well as the required skills for the dive, we had to record our depth and pressure at 10 minute intervals and then our time and depth at specific pressures, regardless of what we were doing at the time, which may have been whilst doing a 2 minute no mask swim at 10m, switching from our back gas to our redundant air source and back, swapping from our regular masks to our spare masks, recording times and pressures in order to calculate a normal SAC rate at various depths, plus several more skills which seem a bit of a blur now; and all the time continuing to stick to the original dive plan that we had individually calculated, and making sure that we got back to the planned exit point. Those two dives that first afternoon were pretty full on, but great fun!
A few days later, we were back on the boat for the final dive of the course and our first solo fun dive! A double dive to Chumphon Pinnacle, which is located about 13km from Koh Tao, and Elaine and I were both very excited! For the final dive of the course, we again had to plan our dives, this time using our actual SAC rates, to determine how long our air supply would last at much deeper depths. After a few adjustments – we were both somewhat over enthusiastic about how long our air would last according to the formula – we both had our individual plans! The Self Buddy Check were done, and as we agreed, we descended down the buoy line together; once at the bottom of the buoy line I chose one direction and Elaine the opposite.
And then I was alone! Looking at my slate to re-assure myself as to the tasks I had to complete during the dive, I set off to explore on my own. All I can say is it was awesome! As I gazed out across Chumphon Pinnacle, going exactly where I wanted to go, without having to wait for my buddy or catch up with anyone, I felt completely at ease. Now I understood what all my underwater videography/photography mates were talking about! At the end of the dive, having followed my plan, the final skills to complete the course were the SMB deployment and then the 3 minute safety stop whilst breathing from the redundant air source. I had already bought myself an 85L “Spare Air”, and although I had had a short go with it on a previous fun dive, it was good to know that I didn’t run out of air on the safety stop!!
Elaine and I came up from our dives within a few minutes of each other, and were both very excited to tell each other about our first solo dives! I don’t think either of us listened to the other because we were both so busy talking at each other! An hour later, we were ready to jump in again for our first post-course solo dives – no skills – just diving. I spent the best part of 30 minutes ambling around Chumphon Pinnacle, without seeing even the bubbles of any other divers. I have done a fair amount of dives, peering in amazement at wonderful and weird critters, riding along heart-stopping currents and hanging with mantas, dolphins and mola molas, but this was definitely up there in my top 10 dives.
So what did I learn – planning is paramount, regardless of how experienced you are as a diver; knowing your strengths, and your weaknesses, to better prepare yourself in the event of a mishap or emergency; and appreciating that no matter how long you have been diving or how experienced you are, there is always something new to learn!
A big thank you to my instructor, Wilco, and to my “non-buddy”, Elaine!! Let’s do it again!!!
Haha – good question! I’m beginning to wonder that myself after just having tried some equalization exercises…..
But seriously, I have always wanted to do it but I never really got around to it I guess. I always thought it would be good skill for photography and videography which I love with my scuba gear on so why not without?
A favorite day out for many staff members is a trip to Sai Daeng beach, and while we all enjoy the snorkeling and shark spotting there it would be so much nicer to be able to spend more time underwater there without scuba…and get some lovely photos too. I can never manage to stay down long enough or hold still enough to photo or be steady and swim around enough for video…. so really that was my goal.
Then a little over a week ago I went out to get some photographs of the guys who were completing their free diving course and I was quite frankly very jealous ! Why ? Well, there was I in my clunky movement inhibiting scuba gear not very gracefully trying to move around fast enough to photograph them as they swirled fluidly through the water. Captivated ! I wanted to do that… So that’s how I find myself about to take the plunge tomorrow…
So myself and a few of our Divemaster candidates in training embark on our new underwater adventure tomorrow. We have instructions not to drink alcohol or consume dairy due to mucus production…… and not to consume caffeine as that will raise our heart rates – none of which are desirable for relaxing and easy equalizing……..