Trimix course preparation?

[pressure tested]

Some of you probably remember I was asking about a trimix course near the beginning of the dive season, this year. However a good deal of you guys on here recommended giving it another season to build up a bit more experience with twins. That is exactly what I have done.

I will be looking to do a trimix course at some point in march, next year. I have been wondering about the details of the course and have read some great trip reports giving a real incite into what to expect. However It seems some people say do the course 'cold' and try and learn as much as you can on the course. Others suggest more preparation. I went into advanced nitrox and deco 'cold' and found it to be really hardwork. I intend to turn up a lot better prepared for this course.

So what do you recommend, how do you prepare for a course like this. Just practice shutdowns and stage drills etc. Is there anything more in terms of inwater skills that expand from advanced nitrox+deco. It would be great to know so I can get practicing in the winter. Or are most of the skills just polish on what is learnt at advanced nitrox+deco level.

Also,(sorry to go on with the questions) but can you do this course with a manifolded twinsetwith the isolation valve closed. Forming essentially 2 cylinders, having a SPG on each of the first stages. My drysuit is too tight in the arms so cannot do shutdowns without undoing waist strap and hoiking the set up a bit. I don't think I will ba able to get a new drysuit and do the course, or is shutdowns part of the course, where you fail if you cannot do them regardless.

[Rob Dobson]

I reckon that the Adv Nitrox and Deco courses are the best preparation (if taught correctly) and if you've already completed those with a decent instructor and you are nailed in the water and can consistently hold all of your stops then I'd say you were good to go.

[warmwaterdiver]

Originally Posted by pressure tested

I will be looking to do a trimix course at some point in march, next year. I have been wondering about the details of the course and have read some great trip reports giving a real incite into what to expect. However It seems some people say do the course 'cold' and try and learn as much as you can on the course. Others suggest more preparation. I went into advanced nitrox and deco 'cold' and found it to be really hardwork. I intend to turn up a lot better prepared for this course.

I did mine this year in March and it was bl**dy cold

Originally Posted by pressure tested

So what do you recommend, how do you prepare for a course like this. Just practice shutdowns and stage drills etc. Is there anything more in terms of inwater skills that expand from advanced nitrox+deco. It would be great to know so I can get practicing in the winter. Or are most of the skills just polish on what is learnt at advanced nitrox+deco level.

get the course schedule to see what your likely to have to do and practice it

Originally Posted by pressure tested

Also,(sorry to go on with the questions) but can you do this course with a manifolded twinsetwith the isolation valve closed. Forming essentially 2 cylinders, having a SPG on each of the first stages. My drysuit is too tight in the arms so cannot do shutdowns without undoing waist strap and hoiking the set up a bit. I don't think I will ba able to get a new drysuit and do the course, or is shutdowns part of the course, where you fail if you cannot do them regardless.

speak with an instructer (Mark Powell on here comes highly recommended) but its more to do with attitude, I have a "similar" issue, the instructer was told and he didn't see it as a problem (and it wasn't) but you must have the answers to the questions the instructer asks to get round your problem, ie if you can't shutdown, you must allow enough reserve in either cylinder (individually, not in total) to get to your next gas switch

[ardhill]

Have you thought about inverting the tanks? There are a few different protection bars now, you don't have to just go with the CD ones if you don't want to.

You don't need flexibility in your suit for invert shutdowns.

Though you will again need to speak with the instructor to see that he is happy with you diving inverts.

[warmwaterdiver]

Originally Posted by warmwaterdiver

but you must have the answers to the questions the instructer asks to get round your problem, ie if you can't shutdown, you must allow enough reserve in either cylinder (individually, not in total) to get to your next gas switch

ah yes, I forgot, never say "I won't have to worry about that as I can't remember the last time I had a freeflow"

[pressure tested]

I think inverts would cost a lot and be a heck of a lot more hassle to me than buying a new drysuit. It is only really a short term cannot do shutdowns situation. In a few years when I have worn the suit out and am looking fo a new one I will try to remind myself to get one that fits Thanks anyway for your advice.

Are there any instructors on here that can answer unanimously, if keeping an isolator shut is O.K for a trimix course.

[Roobydoo]

Originally Posted by pressure tested

Are there any instructors on here that can answer unanimously, if keeping an isolator shut is O.K for a trimix course.

Well, as far as I can see, doing the course with the manifold closed is just the same as if you had independant tanks - with regs & SPG on each post. You just need to be more disciplined in how you use them, i.e. breathing down a certain % of gas, and then changing regs, breathing down the same % in the next tank, and changing back etc.....

[Mark Powell]

It's always worth practicing the basics before going on to the next level.

As you have done the Advanced Nitrox and Deco Procedures courses I would suggest going over all the skills for this course as a refresher. In particular buoyancy control, holding stops and ascent rates needs to be second nature. The assumption in TDI is that the exit criteria for the previous course is the entry criteria for the next.

I've also included the relevant section of the standards so that you can see what is expected.

Trimix
As part of the graduation requirements from this TDI course, your instructor should test your competence in the following areas. Drills to help build your confidence and comfort doing these skills should be taught as part of the regular program.

You will be expected to:
• Be competent in skills required to graduate from any prerequisite TDI course (or equivalent)
• Properly analyze all gas mixes to be used;
• Calculate and mark the MOD (Maximum Operating Depth) of each mix appropriately;
• Demonstrate adequate pre-dive planning (Limits based on team experience, gas consumption of individuals and of team as a whole, oxygen depth and time, inert gas depth and time, environment, contingency and so on);
• Properly execute a planned dive(s) within all predetermined limits;
• Satisfactorily complete TDI written exam;
• Demonstrate mature and responsible judgment concerning dive planning and execution;
• Maintain a high level of awareness and respect for the environment in which all diving and dive preparation is conducted;
• Log all dives

Skills done on land or in the field
• Demonstrate familiarity with basic and intermediate hand signals
• Selection and preparation of equipment suitable for soft overhead environment with long decompression obligations
• Conduct team oriented drills for lift bag deployment and gas switching procedure
• Drills for buddy rescue

Pre-dive skills
• Use START* before every dive
• Stress analysis and mitigation

Skills during dive
• Demonstrate buoyancy control (ability to hover at fixed position in water column without moving hands or feet)
• Show good awareness of buddy and other team members through communications, proximity and team oriented dive practices
• Demonstrate competence managing two stage cylinders (either two deco gas or one deco and extra bottom gas) including drop and recovery while maintaining position in the water column
• Demonstrate ability to confirm gas switches at depth with buddy/team members
• Demonstrate lift bag deployment from depth and use of bag as back-up buoyancy device
• Demonstrate air-sharing ascent from depth while one member of buddy team is without mask
• Create contingency decompression schedule after simulated loss of decompression gas
• Demonstrate ability to manage multiple failures
• Create contingency decompression schedule after simulated loss of decompression gas
• Demonstrate controlled ascent with simulated toxed diver including surface tow at least 30 meters with gear removal on surface (in water too deep to stand in)
• Complete a horizontal breath hold swim at depth for 15 meters with mask off or blacked out