November 2021 – TDI trimix training course

Report by Andrew Bradford

Maybe it was lockdown but late last year I decided 2021 would be a year of training, preferably with other agencies in the interests of variation and learning different ways of doing things. In Feb I completed an SDI solo course….complete Sport Diver and then have two of everything kit-wise about covers it. In November though I booked myself on a TDI Heliotrox course – effectively an entry-level Trimix course placing limits on the max He (35%) and the min O2 (21%).

I spent the summer working through the coursework and exams which were delivered online. Academically the course is split in two – Decompression Procedures and Extended Range. Compared to BSAC I was struck by the shear number of hand signals…which if mastered allows quite detailed conversations to be had…..there was also a chunk of content relating to Closed Circuit diving. Predictably there is also a large amount of content relating to decompression models, their history and also the theory between the different models and their outcomes…of real interest when dealing with trimix is the different behaviour of the gases through the dive and situations in which the body might be off-gassing one but on-gassing another.

However, from a pure gas mix perspective its really only a stage on from Advanced nitrox/ADP for BSAC.

We then had two, two-hour learning sessions with the instructor – the excellent and it seems reasonably renowned Toni Norton.

A Weekend at Vobster was the location for the in water aspects. We started with a kit review which I was slightly surprised to find my independent twin setup passed with surprisingly few negative comments. There were a number of important mid-water skills to demonstrate such as shutdowns, out of air, lost mask, de-clipping stage cylinders, DSMB deployment etc all while remaining neutrally buoyant. Dive planning and executing the plan precisely was a really bit feature of the course which can be challenging if people are running different deco models on their computer.

Final dive involved a trip to the silty bottom of Vobster including dealing with just about everything going wrong that could go wrong as Toni really turned the screw. Forcing me to deal with out of gas, a shutdown, loss of deco gas & then intentionally dropped some kit to see if I would chase it while breathing a deco mix.

BSAC’s equivalent course is the mixed gas 50 course. I did this course, partly to try another agency and partly because it was more available as I think BSAC Southern has been struggling to lay on courses out of lockdown. Very glad I did it and looking forward to practising my new skills. Either way, the real benefit is in those skills rather than the gas certification. The one thing I will continue to learn are the hand signals which seem more comprehensive than anything I’ve experienced before. I believe George will be completing the course next year. Three big take-outs from the course:

  1. Buoyancy is king
  2. Plan the dive and dive the plan (meticulously)
  3. When things don’t go right…relax and chill…when they still go wrong….keep chilled.
Posted in News