TDI Adv Nitrox & Deco Procedures – Part 2


The next morning we woke early and headed to the dive shop for the days tech diving lessons. We got our twinsets rigged and with the aid of a very expensive yellow thing we were taught how to test our gas. When you become a tech diver the stuff in your cylinder is no longer called air, even if it is. It’s called “gas.” I’m all about these new terms, made this me feel even more like a tech diver. So gas tested, we would be diving 32% nitrox.

Malta Shoreline
We arrived at the dive site, dropped the tailgate on the truck and got our kit together. We were taught our new tech diving buddy check – START. This is a relatively simple procedure which is really just an extension of the standard PADI pre-dive checks. I did learn to smell my gas from now on though. I had a vague recollection of having to sniff your reg pre-dive when I began my open water course, but I had got out of the way of it and subsequently forgotten completely. This was really the only part of my pre dive checks that I had trouble remembering to do. So, scratch and sniff then on with the new START check.

S-Drill: Out of gas drill (dry and in water) and bubble check (in water only)

Team: check gear of you and buddy

Air: check gas matching with buddy and that computer is set properly to the mix

Route: check entry / exit points and dive profile

Tables: depth, duration and schedule, bail out plans

So, with all our checks done we headed to the entry point. There was a little bit of swell on the surface which we weren’t used to, it was a bit daunting jumping into what I thought was rough seas. It was fine once we were in and we descended about 2m and did our bubble check which consisted of a quick once over each other’s manifolds to check for leaks. To be honest, this does require decent buoyancy control. I found once I began concentrating on something I tended to sink and then I had to readjust my wing to compensate. Frustrating. This was something I focused on the rest of the week and it definitely improved with practice.

David jumped in and with his single 10 litre cylinder, he appeared to need so little air it was just plain irritating, gave us the OK and we began the dive. The water was 15C and I was pretty comfortable, if a little too warm. We swam along the reef and then headed out into the blue in search of the Rozi shipwreck. I later learned this was called a “blue water swim.” This is basically when you follow a bearing into practically vacant space, holding your depth at a set level until you reach your target, in our case the wreck. To my annoyance i not only found it hard to maintain constant depth, but it also freaked me out a bit. It seemed floating in the middle of nothing was a bit disconcerting, almost agoraphobic. I kept my head and out of nowhere a wreck loomed out of the darkening blue. It was fantastic, I wasn’t used to diving in this sort of visibility, in the UK waters I tend to bang my head on a wreck before I see it!

We reached the deck of the wreck and I switched on my trusted can light, as I could see dark swim throughs that had to be investigated. We swam into the wheel house and through some other short openings in the wreck. I had a little narcosis, I think, as I felt a little insecure at 30m which was my deepest dive to date. I don’t know why, I just did. I gave Kerri the “buddy up” signal and we closed in and within 30s I was back on track after getting some quick reassurance from wife-buddy.

Approaching The Rozi
After 20 mins we headed off the wreck back and into the blue and finally hit the reef again. I did feel a little relief in seeing the familiar sight of the shore and we ascended to 14m and David gave a signal that we would be doing some drills. I knew the good parts were over, well, kind of. OOG was first up and wife-buddy and I successfully donated our long hoses. I was quite enjoying the drill and felt a lot more comfortable with the technique involved. Next up was the valve drill. I could read Kerri’s eyes and I knew she was totally focused on getting it right on this one. I found my drill simpler than the previous day and had it completed in decent time. Kerri unfortunately was still struggling with her isolator, the final part of the drill. She was so close but had to give up in the end.

We surfaced and went for some lunch at a nearby diner and conducted a dive debrief. Kerri was happier than I had expected which was always positive. The fact she was so close seemed to spur her on even more to get it on the next attempt. I was feeling quite positive about the whole thing. Having so much “gas” with me was both a comfort on the deeper dives and fantastic due to the extended time in the water we were getting. David had kindly loaned me a higher spec computer and we were able to work out our SAC rate for the dive, for me it was 18l/min. I was improving. Good. Lunch done and 2.5hr surface interval we were good for a second dive.

I expressed to David I was a bit freaked out about the blue water swims so he suggested we repeat the morning dive as I knew it and therefore wouldn’t be as stressed. This was a splendid idea as far as I was concerned and really made me feel a lot better about the pending dive.

Back at the entry point we donned our suits and gear, did our START checks and headed for the water. Concentrating more on our buoyancy Kerri and I had a better S-Drill but we still needed to work on it. We gave David the OK and headed into the blue again in search of the wreck. In the process we also went through some interesting natural tunnels in the reef. These were just a little too tight and a little too dark for my liking. The constriction was bearable but once the natural light faded I felt a little on edge. It was a relatively short swim through, it just felt longer as I was concentrating so much, but it was fun and confirmed everything I knew about myself and I would never make a cave diver.

Kerri wreck diving
We reached the wreck and investigated the wheel house again and conducted some more challenging swim throughs. I was really beginning to enjoy swimming in and out of the holds and wheel house with my torch illuminating now abandoned rooms and corridors. It was eerie, but inviting. I could really begin to understand why untrained divers venture into wrecks and end up very dead. The urge to just have a quick look down one more corridor and accidently lose sight of the exit was very strong. But, being a highly trained tech diver I resisted and as a result am very much alive.

We left the wreck and I attempted some horrendous underwater photography as we caught sight of the reef once again. We knew what was coming next and I was fully prepared for the drills that would surely follow. Like a conductor David signalled at us to begin our OOG drills. We were definitely getting more comfortable with the long hose system. Then the valve drill was to be done again. This time I thought I would try and focus more on my buoyancy and awareness whilst conducting the drill. Fine in theory. I tried my best to stay flat in the water and reached the valves no problem. I scanned my surroundings as David was attentively watching Kerri as she closed her main valve and a little fish swam by. I then realised I had no idea if my reg was open or not. Great. Now I was going to drown. I switched reg and it soon tightened and then nothing. Turned out I hadn’t opened it again. Well done Andrew; in a real situation you just killed yourself. Wife-buddy and the ever increasing cat army would be enjoying my house alone from now on. My only option was start all over again.

I finally completed my very aware and awesomely controlled shut down then drifted above Kerri just in time to see her complete her first ever shut down drill! High fives and underwater applauding followed this momentous achievement, I was thrilled. A good day out and I knew Kerri would be over the moon and I was guaranteed a pleasant evening. The dive came to an end and we survived the rather slippery exit and made her way back to the truck and finally, to the dive shop.

We were then quickly ushered to the classroom having emptied the truck and rinsed the kit. Next up was the TDI Advanced Nitrox exam. We took our papers and got to work, utilising all our new fangled, ever increasing, tech diving knowledge base. I was a little disappointed in the lack of multiple choice. This wasn’t going to be as straight forward as I had hoped. Nonetheless I answered everything as best I could, with Kerri scribbling ferociously beside me, covering her answers with her hand as she knows I’m a cheating bastard.

We passed - I Are Tech Diver.


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Safe diving buddy.