Article: Learning to Technical Dive

*Note: This a re-blog from a review I wrote back in 2012 on the Diving Leisure London blog. During my time working for this awesome, London based dive shop, I completed my Technical Diving Courses. Here is the review I wrote all those years ago about these courses. I have since mildly edited to the post to read better – and also I have added photos!


So aside from being very busy with all the usual day to day life here at DLL, there have been rumblings and rumours with regard to adding the full range of PADI technical courses to the already huge repertoire of courses available on the recreational diving menu here.

This summer, I had the pleasure of being guided through the Tec 40 and Tec 45 programmes, and I am writing to share my experiences. This will allow you to see these courses from the point of view of someone who is actually going through the process of becoming a fledgling technical diver. Hopefully this will help allay some of the fear and intimidation that goes along with the big decision of becoming a technical diver.

The knowledge development session kicked off the course and basically entailed me being sat down on the floor of the classroom with a twinset strapped to my back. I was learning a whole new way and mindset to approaching diving and dive planning. However it didn’t take long for me to realise that it actually all made logical sense! This new point of view actually helped me to see recreational single-tank diving in a whole new light too.

Next up, Alex and I (and Jen – if anyone remembers the avengers photo – see below) trotted off to Wraysbury Dive Centre where I strapped on the twin tanks and a stage tank too, and jumped in the water. After the initial fumbling around attaching the stage clips to the harness, we descended. It very quickly became immediately apparent just how nice it is to dive this type of gear configuration.

Think back to the days when you first strapped a tank to your back and jumped in the pool  – remember that feeling of the tank’s weight pulling you to one side or the other? Naturally the human body quickly develops the muscle memory and core strength to automatically correct this, so after a few hours you are fine. Once you dive in a twinset, the first thing you notice is just how stable they are, there is absolutely no rolling to one side in the water. The even distribution of weight, coupled with the aforementioned muscle memory meant I felt very relaxed and comfortable quickly.

It does initially feel odd that with every fin kick, the stage tank that is clipped to your left hand side rhythmically swings back and forth a tiny amount, and yes, for sure, the shut down drills are a bit of a bugger to start with, but these skills are absolutely nothing compared to doing your first ever no-mask swim or a Buddha style hover in your Open-Water Diver course. The rest of the skills in the Tec 40 course are basically developments of already ingrained abilities as a diver and so are relatively easy to tackle and develop.

The real beauty came with the qualification dives. 40 metres! (130′) For those who struggle to conceptualise numerical depths – 40 metres is approximately a twelve story building!

To put things into perspective, let’s take a quick look at what it actually means to dive to 40 metres on a normal recreational dive. 40 metres underwater with a single tank, a single regulator and often a single means of buoyancy is actually a frightening concept, especially when you consider that only one of those things needs to fail and we have a very interesting ascent ahead of us! Yet many recreation divers will happily do that type of dive, yet will still refuse to consider getting into technical diving.

Yet, when we compare that type of dive to a technical dive to the same depth, we now have two (or more) cylinders, two regulators, two means of establishing and maintaining buoyancy. Not to mention a plan, and a back up plan etc. We have so much redundancy and planning, we are not simply splashing into the water and blindly following our computers and pressure gauges.

Both of the above are considered perfectly acceptable ways of diving into the depths – but which one would you feel more comfortable with? Hopefully this inspires a little confidence that technical diving isn’t quite as gung-ho and out of reach that many consider it to be.

Time to dive! We descended down the line to 40 metres, and as the faint whiffs of narcosis seeped in, I began to really enjoy the dive. The great visibility in Chepstow, and the huge cavernous walls stretching up to the surface and away on either side it gave the impression of being in a massive cathedral. and the effects of the nitrogen really adding an edge to the whole experience. As a Tec40 diver, you are limited to no more than ten minutes of decompression, and so it was with a heavy heart that we began our ascent to our first decompression stop at a depth of 21 metres, and we switched to our stage tank containing 50% oxygen to add a level of conservatism to our decompression schedule. (At this early stage, using higher oxygen percentages to accelerate decompression is not yet permitted.)

After a mere 10 minutes, we surfaced. I was elated to have added another plastic card to my quiver and to have finally joined the realms of technical diving.

I was hungry for more as we began the next course – Tec45.

The initial skill development dives were much of the same, but now it was expected that a higher degree of control was to be needed. Shut-downs were now timed and had to be done neutrally buoyant. (Although with my instructors – they encouraged this from the beginning anyway.) The gas-sharing drills were now conducted without a mask, and SMB deployment and use of the spool had to be slick.

These dives were where I really began to feel my skills as a diver sky-rocket, and I finished the day at Vobster Quay feeling great. It now felt that the things the three musketeers (David, Alex, and Maxim) talked about endlessly had started making sense – rather than sounding like a foreign language. Everything was falling into place, and the tasks where I may have stumbled before, I now didn’t even take a second look at. My level of knowledge especially concerning dive planning and what is expected of me as a more experienced diver increased massively.

By the time of the qualification dives at Chepstow, I actually felt like a member of the team; planning and executing a technical dive – rather than a student simply being taken for a dive. We sat down over coffees and discussed the plan, and we came to an agreement together regarding bottom time, stop depths, stop times etc. I felt like I had enough knowledge to contribute usefully to the conversations and I actually really enjoyed the process.

The final dive itself still stands out now as one the single best dives of my career so far. The four of us descended the line almost in free-fall, the fast yet smooth descent meant we actually had 18 minutes to spend on the bottom – which at 45 metres (150′) is pretty damn cool! The great thing about Tec45 is the fact you now are permitted to do an unlimited amount of decompression, as opposed to being limited to ten minutes as before. Also, I now had the ability to use up to 100% oxygen to accelerate my decompression stops meaning less time hanging on the line. The two factors combined effectively means more time doing that actual dive without being penalised so heavily with decompression requirements – excellent!

We swam at 45 metres following the wall of Chepstow quarry for what felt like an eternity. Later, Alex and I would discuss the effects of narcosis on time perception, but while I was down there all I know is that I loved it and I didn’t want it to end! Although certainly I was not clear-headed, the great training I had received, and the thorough preparation we did meant I felt at ease and in control. This feeling of being relaxed, and the smoothness of the dive meant I actually had a pretty good gas consumption rate, and the dive went brilliantly.

We returned to the line and sat watching our timers, and as our runtime hit twenty minutes, we began our ascent to our first decompression stop at 27 metres. We were all smiles as we ascended to our gas-switch depth, and continued upwards. The warm thermocline bringing much relief to numb fingers, and Maxim had written a slate to congratulate me whilst hanging out at 6 metres.

We surfaced in great spirits and went for much needed curry and beer! Next stop – 50 metres and beyond!


Authors note: (May 2020) – Since originally writing this post in 2012, I have since gone on to attain full Trimix certification with a culmination dive to 100 metres/330 feet. (blog coming soon!) Another notable dive is one I did to a shipwreck hanging over a drop-off at 70 metres/230 feet in the Cayman Islands! Read about that story below.


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