The usefulness of deco training without trimix

[beester]

Thanks for the explanation. Very interesting. I had been assuming (there we go again!) that GUE Tech 1 was basically normoxic and Tech 2 was hypoxic. Since GUE teaches trimix almost right off the bat (i.e. Rec 3?), and has such stringent requirements to get in (i.e. Fundies Tech pass) I didn't find it hard to believe that Tech 1 would be full normoxic trimix (i.e. unlimited deco, to 60m). I didn't know about the "extras" like T60 and T2Plus.

Obviously I'm not a GUE instructor so I don't exactly know what the rational is behind this split and course structure, but it is like this.

T1 IS full normoxic trimix (specially if you would take the max depth as avg depth which many students do after class). But there is more to a tech certification then depth limit. In my book it's not only about the gas you breath (although procedures do change when you start handling hypoxic mixes), but more about the ascend strategy, gas planning, emergency procedures, etc...

That is part of my critique on your "bigger" dive... In my book the level of a dive changes the procedures you use (ascend strategy, gas planning, team, emergency procedures) and this level is not only dependent on depth but also bottom time. For me a 130ft (40m) 1 hour bottom time dive is a full trimix dive. Not because of Helium used, but because of the planning of the dive, gas management, ascend strategy and emergency procedures are more in line with a full trimix dive than a AN/DP dive. It's in my book a multi stage dive.

Below pic is me on a recent 45m avg dive with a 1h bottom time... that's not so far from your dive in total run time or ascend deco time and as you can see it's a 3 stage dive.

So if you are doing such dives regularly (and it's not a one off), I would start looking into further courses which will give you additional tools to better plan such a dive. At least it will give you the options to decide how to organise such dive, instead of pushing the limits of what is feasible within AN/DP and 1 stage.

The Tech60 (in the past Tech 1 +) was put in place because the step from T1 to T2 was very big and many wouldn't take the T2 step because of this. Next it's not an easy course... I know 4 good divers in my network who are full cave and tech 1 trained within GUE and got a provisional on T2 (not passing the course). I think I can say this (althoug I'm subjective of course) having done courses with different agencies is that the bar is very high on GUE courses.

 

[victorzamora]

T1 IS full normoxic trimix (specially if you would take the max depth as avg depth which many students do after class)

I'm not sure that that's the case. T1 limits are a single (one of two) deco gas, one of two bottom gasses, and a max of 30min of deco. I'll even ignore the rigidity of standard gas usage because I like and buy into that....but it IS one factor.

I'm using TDI Trimix Diver as a comparator, and I'll be ignoring the strict implications of "Normoxic" trimix being a mixture of 21/XX as what it's colloquially used as is 18% O2 or greater.

T1 has a limit of 170ft while TDI's Trimix Diver has a max depth of 200ft. TDI puts no limits on deco time or on deco mixes carried.

I understand why GUE does it that way, but one deco gas and 30min of deco is too limiting for me to call it "full normoxic trimix." I mostly dive caves, which I know is a bit of an oddball, but following T1 limits would be too constricting for me.

 

[_Ralph]

Sooo much "interesting" information being provided by people who haven't done what they are talking about .....


Anyways, back to the OP


I haven't done the TDI route, but can comment directly about deco without trimix, as that is roughly 1/2 of my "tec" dives that I do ....

32% bottom gas, with 100% deco.

Lots of fun, without the added expense of increasing your gas bill by a few $$$. Can usually dive it "locally" and abroad fairly easily (last trip in the Caribbean, had some nice 70-80minute reef dives on 32% with O2)

Now, if you're looking to explore in the 30-60+m range (100-200+ft), that Helium can be a big advantage to your overall happiness and comfort during the dive.



_R

 

[beester]

Well I have taken AN and normoxic trimix with different agencies. (AN with TDI, normoxic with IANTD and T1/T2 and other with GUE)...So I think I have a grasp of the topic matter.

Not making this into a this vs this federation. Maybe yes you shouldn't consider the GUE T1 with a normoxic course based on depth or deco (on the other hand T60 is certainly normoxic plus). However from pratical point of view the 1 stage (which I consider normoxic range) is the limiting factor. That being said from the different deco courses I took on normoxic level I honestly can say that I learned the most from the GUE course, specifically when it comes to getting the tools to do the dives. (but of course that's subjective and also depends on instructor).

How do other GUE trained divers feel about above?

 

[cool_hardware52]

I do enjoy IANTD Deep Air and Adv Nitrox course back in 1998.
Twin set + one 50% deco mix. Deco was actually very short.
A great introduction to Technical diving. If I remember correctly both courses were NOT regarded as tec course.

Humm, Deep Air and trouble remembering, could there be a correlation?

Tobin

 

[Jack Hammer]

How do other GUE trained divers feel about above?

Not to knock AN/DP, it is a good starting point. I learned more knowledge and skills in T1 and had a much better understanding of both than I did in AN/DP. The in water skill set standards required to pass AN/DP was about on par with adding a bottle and a gas switch to a recreational pass in Fundies. In fact, my Fundies class was quite a bit more difficult and covered a LOT of info not covered in AN/DP. And my AN/DP instructor was GUE trained and included more than the TDI minimum standards. He was the one who recommended I take Fundies, I'm extremely glad I did. It added a lot to both my recreational and technical diving.

 

[victorzamora]

Well I have taken AN and normoxic trimix with different agencies. (AN with TDI, normoxic with IANTD and T1/T2 and other with GUE)...So I think I have a grasp of the topic matter.

Not making this into a this vs this federation. Maybe yes you shouldn't consider the GUE T1 with a normoxic course based on depth or deco (on the other hand T60 is certainly normoxic plus). However from pratical point of view the 1 stage (which I consider normoxic range) is the limiting factor. That being said from the different deco courses I took on normoxic level I honestly can say that I learned the most from the GUE course, specifically when it comes to getting the tools to do the dives. (but of course that's subjective and also depends on instructor).

How do other GUE trained divers feel about above?

I didn't mean to make it sound like a bash of one agency or the other, I simply wanted it clear that it's not really a direct parallel. For open water technical diving, I'm not sure there's a ton of difference between Tech1 and something like TDI's Trimix Diver.

For cave/wreck diving, T60 seems to have the same issue that T1 has: A single deco gas and a 45-minute deco limit. The vast majority of my diving is done in the caves, and a 45-minute deco limit is just not enough. For most caves at Trimix depths, a single deco bottle is just not enough.

I understand why GUE does it this way, and I'm not meaning any of this to be agency bashing. I'm simply trying to say that they're not parallel.

 

[stuartv]

my Fundies class was quite a bit more difficult and covered a LOT of info not covered in AN/DP.

Would you mind giving some examples of info not covered in AN/DP that was covered in Fundies?

 

[PfcAJ]

The biggest "limit" to tech1 is the use of a single deco gas.

Signing up for more than ~30mins of deco or depths greater than 170 or is not wise with a single deco gas.

 

[fsardone]

The biggest "limit" to tech1 is the use of a single deco gas.

Signing up for more than ~30mins of deco or depths greater than 170 or is not wise with a single deco gas.

How would handle a lost gas?
Team deco? It would be impractical to carry enough bottom gas to do deco on it in case you lose the single deco gas. And usually you find out when you need it!

cheers