The DIRdudes are all GUE trained and dive DIR, no surprises there, but we also maintain a healthy interest in what other diving training organisations can offer and after completing GUE Tech 1 in 2007 we were interested in the TDI Advanced Trimix Course as a warm-up ahead of doing Tech 2 later this year.This course provides the training required to competently and safely utilise breathing gases containing Helium for dives that require staged decompression, utilising Nitrox and/or Oxygen mixtures during decompression to a maximum depth of 91msw. This new adventure promised challenges and excitement whilst calling upon all of our previously learnt skills, knowledge and experience.
Getting to know you...
We contacted Callum Girvan at Dolphin Scuba because of his reputation as a first rate TDI Instructor (he has subsequently been awarded TDI Instructor of the Year 2008). We arranged an informal meeting to discuss our interest in the course, understand the prerequisites and get to know one another.
Its an interesting dance at this level of diving, when both the instructor and the students are very experienced. We had already done our homework before approaching Callum and we were satisfied that he was the best instructor available in our area. Likewise after meeting us Callum not only checked our credentials but also our reputations in the local dive community. Given the seriousness of the diving on this course it was good to see this level of selectivity before accepting candidates. A further check with Richard Taylor at TDI HQ established that our GUE Tech 1 qualification was sufficient as a prerequisite for the course so all was fine on paper. Justin and I were joined on the course by Josh who had just completed an instructor qualification and was about to enter the Navy as a Clearance Diver.
In addition to clearing the certs we wanted to see how each other performed in the water so we arranged to join Callum on a couple of his upcoming Extended Range course dives, in this way we could assess each others abilities and style ahead of the course.
The Course
The course itself consisted of about 10 hours over three evening classroom sessions covering the academics and four skills assessment and pre-qualification dives.
The classroom sessions provided an opportunity to discuss the similarities and differences between GUE training and TDI, this was done with a health dose of good natured piss-taking from both sides. Whilst Callum and Josh are both successful and dedicated TDI divers they were somewhat interested in hearing about how the use of standardised gases provided the framework for deco on the fly (ratio deco). The course itself covered diving physics, physiology; deco gas options; equipment considerations; dive tables and theory; dive planning including support, team and emergency plans; procedures and contingency.
The training dives likewise provided an opportunity to compare technique; given we would be diving with three deco/travel cylinders (2 x S80 + S40). This gave us an opportunity to show off (and practice) the use of a stage leash and the DIR technique of multiple-cylinder switching rather than carrying two deco cylinders on the left and one on the right side. We also had discussions about the rationale behind DIR hose routing and the ubiquitous discussions over what constitutes good trim.
Callum was preaching to the choir for much of the course but none the less consistently drove home the need for proper gas analysis, adequate pre-dive planning and proper execution of the plan. The skills dives were fun re-covering most of our GUE Fundies skills. Callum had us demonstrate the basic 5, valve drills, line laying, blind navigation, SMB deployment etc. Our maskless breath-hold swim at 20m was interesting, with all of us learning that we 'dress to the left' :). Removing and replacing stage bottles without a mask was likewise a little different.
Things got even more interesting as Callum increased the task load beyond our comfort level. By the end of the skills assesment we were holding simulated deco stops as a team despite multiple failures. We had two maskless divers and two failed depth gauges! The remaining sighted diver who was OOA had to monitor depth and time on another divers wrist whilst a maskless diver deployed an SMB. We held our stops but it wasn't pretty.
The Dives
To find the depth we needed for this course and a suitable objective for each dive we planned to visit the wrecks of the Rottnest Ships Graveyard. The Graveyard is an area between 5-18 NM west of the West End of Rottnest Island encompassing the entire region between the south-east and the north-west quadrants. The seabed in the region lies between 40-200 metres deep.
The area has been used as a dumping ground for derelict ships and surplus munitions from the early 1900’s until the 1970’s, but some dumping was carried out later than this but usually in much deeper water. There are reportedly around 40 ships scuttled in the area, but a large number of these were old iron “hulks” and wooden ships of which there is little remaining.
Warm-up dive
Max: 58m
Avg: 26m
BT: 20mins
RT: 64mins
BG: 18/45
Deco: EAN50
HMAS Junee?
We planned a 60m warm-up dive on what was supposed to be the scuttled wreck of HMAS Junee.
It was pretty clear however when we got down to the wreck that it was a small bulk carrier and not a Navy vessel at all. Not that it mattered it was still a beautiful wreck teaming with life and there was whale-song in the distance!
Apparently the Junee is nearby, less than 20m from this wreck! You've got to love the graveyard!
Qualifying Dive 1
Date: 7/09/2008
Max: 83m
Avg: 30m
BT: 12mins
RT: 58mins
BG: 15/55
Deco: 35/30; EAN50; O2
Qualifying Dive 2
Date: 28/09/2008
Max: 88m
Avg: 31m
BT: 12mins
RT: 59mins
BG: 15/55
Deco: 35/30; EAN50; O2
We planned a 60m warm-up dive on what was supposed to be the scuttled wreck of HMAS Junee.
It was pretty clear however when we got down to the wreck that it was a small bulk carrier and not a Navy vessel at all. Not that it mattered it was still a beautiful wreck teaming with life and there was whale-song in the distance!
Apparently the Junee is nearby, less than 20m from this wreck! You've got to love the graveyard!
Qualifying Dive 1
Date: 7/09/2008Max: 83m
Avg: 30m
BT: 12mins
RT: 58mins
BG: 15/55
Deco: 35/30; EAN50; O2
An interesting friend at 90m!
Qualifying Dive 2
Date: 28/09/2008Max: 88m
Avg: 31m
BT: 12mins
RT: 59mins
BG: 15/55
Deco: 35/30; EAN50; O2
Conclusions
This was a great course particularly for the intense practical experiences it provided. Overall, given the depth that this course certifies you to to dive, we think the academics are a bit light and there is not enough consideration of team contingencies. This is not a substitute to a Tech 2 course. We were glad we had our Tech 1 training to fall back on otherwise some aspects could have been quite scary. That said it fits well as a complement to Tech 1 and as a preliminary to Tech 2 and Callum rocks as an instructor.
