Recommended depths/times - Shutdowns!

[String]

Late arrival here but my TDI Adv Ean/Deco procedures course we started with the valve drills in about 6m but then did most of them at 3-4m.

[Rod Abbotson]

How many people can walk across a plank of wood that's lying flat on the ground without a stumble or issue. Put that same plank between two buildings a couple of stories up, would they be just as succesful or confident?

Exactly the point I was trying to make. When training recreational divers they, say, remove and replace their masks OK at 5m then refuse when at 18m this just a psychological issue - but the same applies in tec training - AGREED its much more difficult to do a task in shallow water 3m or so and maintain depth or even a meter under the surface. I have my tec students perfect shut down drills in these depths without deco obligation - and sure enough they can then perform them easily at depth except for the narcosis issue which will effect people differently - this is not a "deep air" issue as Clare suggests... otherwise we would have deep every mix issues! Tec Divers work from ENDs as shallow 25m or less down to 70m on He;liair expedition extreme dives to reduce ICBD risk - these have lots of deep experience. BSAC and DSAT work on air at 50m and move to 40m when teaching trimix. TDI is 55m on air - correct me if Im wrong here...

So that was my original question asked END or actual which was then deemed as stupid - as in tec diving it would be the END dictating the speed and dexterity of doing the skill. So if this were the case and ideal mix for a TDI certified diver would be 30m! I have just been diving with several TDI Advanced Trimix divers (certed to 100m printed on their cards working to much higher ENDs!)

Ill have to check the TDI standards myself to get a good anser here just thought someone might know.

[Garf]

Tec Divers work from ENDs as shallow 25m or less down to 70m on He;liair expedition extreme dives to reduce ICBD risk - these have lots of deep experience. BSAC and DSAT work on air at 50m and move to 40m when teaching trimix. TDI is 55m on air - correct me if Im wrong here...

TDi's extended range course does offer a 55 metre ticket on air. however, most of the TDI instructors I know STRONGLY recommend against this course and take their students directly from AdvEan/Decoprocedures to Trimix. GUE work on a maximum END of 30 metres, and teach trimix from this depth. If you simply look at ideal gas and refuse to compromise, the arguments for not using mix from these depths are, IMHO of course, a bit weak.

As for deep drills, what's the point? 60 metres feels just like 20 metres on the appropriate gas. You can do drills all day long in 2 metres, the gas lasts a hell odf a lot longer, and the diver needs more finesse in terms of buoyancy. The speed and dexterity of the drills are impacted by the EDN, but many of us remove END from the equation with mix for this reason. What's left is buoyancy control, team awareness and the ability to maintain the core skills in the event of failures. In addition, there are Health and Safety issues, certainly in the UK, with getting your students narked out of their tits and then throwing failure at them, before you even get into the logistical problems. The answer to dealing with problems and narcosis is to remove the narcosis.

As for "tec" divers do this, "tec" divers do that, what's a "tec" diver? If this a PADI or DSAT term? You're chucking a lot of depth figures around., and examples of how "tec" divers do things. Probably might want to bear in mind the people responding to your questions don't call themselves "tec" divers, but are regularly using trimix, have the qualifications you talk about from TDI, and are regularly diving these depths Perhaps not all technical divers do it the way you think they do. Many of us, for example, will know we can do at any depth, because we train for them in the shallows, and then ensure maintain a shallow enough END that narcosis never becomes a factor.

[James The Badger]

[Howard Payne]

[SoggyFox]

what about inverts?