Wednesday, 19 April 2017


Back in October last year during the  NEC Dive Show I was on the TDI stand and lucky enough to presenting on the TEKDeck Stage.  It was during this time that I decided to chat to Mark Powell about upgrading to a TDI Helitrox Diver instructor.

Launched back in 2010 as a distinctive specialty, Helitrox is now the preferred choice for divers who are looking to safely dive around the 45m mark.  This course has all the benefits of the TDI Decompression Procedures Diver course but with the added benefit of allowing up to 20% helium to take the edge off any narcosis.  Although slightly shallower than its closest rival; IANTDs ART (Advanced Recreational Trimix) (was 48m, now 51m), when combined with TDI Advanced Nitrox Diver, the amount of decompression is only limited to the gas that the diver can carry (and obviously CNS limits), rather than IANTD’s 15 minutes.

Fast forward to December and Mark and I were at Vobster to start the crossover process.  Once all the paperwork was done, we discussed the outline of the day (although this had already been planned via email) and headed into the water for the first of 2 dives.  During the first dive I was to deliver a skills circuit of all the skills required for the course, and then demonstrate teaching of skills during the second dive.

The first dive went generally well, although I am my own worst critic, and I wanted to re-demonstrate mid water mask replacement and free-flow deco gas.  Mark offered encouragement as he knew that I knew the demonstrations were not perfect so we went back down and I re-did the skills and a mini lesson.  Back on the surface we simulated a diver rescue which went well until the de-kit process, but hey that happens.  I just couldn’t get Mark out of his harness.  The reality is that I would have cut it, but I don’t think he would have appreciated it somehow.  It was during this process that I also managed to hole both dry gloves.  The important thing was it was a successful rescue, and it also highlighted the teaching point of how difficult a rescue can be.

Following a debrief and short lunch, we were around the table covering the difference between TDI Decompression Procedures Diver and TDI Helitrox Diver; predominantly the suit inflation issue and benefits of diving helium.  In Mark’s usual style, he was prompting for the answers rather than lecturing, because as per the pre-requisites, I’m already a TDI Trimix Diver.  After this I then had time to prepare the delivery of 2 lectures back to Mark.  This was done using a notebook, the Trimix manual, and a suit inflation cylinder and stage cylinder with suit inflation hose attached.  Again in Mark’s style, at the end of the lectures he asked a number of questions, some of which were TDI Trimix Diver level.  I was able to answer them, and provided a handout for the student/Mark.  Lastly, Mark gave me some useful hints and tips and that was that, course done.

Fairly pain free, despite it not going exactly to plan (the story of my life) I received my certification by email the very next day.

If you want to know more about this course then click on my website here, alternatively the full range of TDI courses can be found here.

The boring bit!
All opinions expressed in my articles are my own and may differ to other instructor’s and agency guidelines; by no means are they wrong and I would not wish to disrepute any of them.  This article is for information only and should not replace proper training.

Safe diving!

Timothy Gort
BSAC, PADI & SDI/TDI diver training
l Mob: 07968148261 l Email: l

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