Is it worth to do OC trimix before CCR Helitrox?

[lermontov]

I am thinking of getting CCR trained while having only TDI ANDP.

I hear all the time that it is worth getting OC Trimix trained before CCR in case you bail out.

What are your opinions on this?

Certification course passes are based on the minimum standard thats acceptable - its entry level. A newly minted person holding a cert card is not the same as a veteran diver with 100s of trimix dives behind them yet they both are 'certified'
My take is that the cert scheme is still based on a single tank - twins- deco bottle progression. whereas in reality more and more people are going from single tank - sidemount-deco bottle progression which means the base skill of carrying tank in CCR BO style are already in place- any transition to ccr is not such a big jumping terms of tank management.
if you have a solid base of tank management -(and your already have ANDP so you are on that path) then forget about the OC trimix and get on the ccr - adding helium to your gas is not is not that big a deal until you get to hypoxic mixes, and then theres another thing to kill you.
Caveat- only you know if your comfortable on tank management -an ANDP cert is the entry point you need to be honest with yourself - a problem on a ccr can overwhelm you pretty quickly if your fluffing around with your BO tanks. Get your slung tank, hose routing, reg swapping skills SOLID -it will be your foundation for everything else

 

[doctormike]

There will be enough to think about in your CCR class without having to do it while narced. If you have a trimix or helitrox ticket before you start you can use it as a diluent from the get go.

No one is going to let you do MOD 1 at depths where you would be narced. You can't even do deco, let alone trimix depths while you are figuring out the basics of rebreather diving. I'm not a CCR instructor, but I would be surprised if any agency let someone start their CCR training with helium as a diluent.

I never did OC trimix, I started CCR training with TDI AN/DP, like the OP. I did helitrox after doing a good bit of air diluent diving on my JJ.

 

[rongoodman]

I came to my IANTD MOD1 class with a Normoxic card and used mix on every dive. There was no reason not to. There is obviously some disagreement as to what constitutes “trimix depths”.

 

[doctormike]

I came to my IANTD MOD1 class with a Normoxic card and used mix on every dive. There was no reason not to. There is obviously some disagreement as to what constitutes “trimix depths”.

Why? How deep were your MOD1 dives?

CCR is so different than OC diving, there is so much to learn, no matter how experienced you are on OC, why would you add helium before getting the basics down?

I'm seriously asking, not trolling, just interested.

 

[rongoodman]

It's been a few years so I don't remember details. The shop banked 21/35 and that's what we used. I doubt they would do the same today with the current suppy issues. I'm not sure what complications would be involved by adding helium, though. It's less dense and easier on the scrubber, as well as being less narcotic, so what's the downside?

 

[Tracy]

I just taught a Helitrox class. I'm assuming it will be my last one. The amount of He in the mix is close to being inconsequential (END of 113 on a 150' dive, at best), but more importantly getting He for open circuit is basically a non-starter at this point. Even if I can get it for class, the students won't be able to get it to conduct dives. They'll be stuck doing 150' dives on air, which they wouldn't have done before.

Just go CCR. It will change your diving point of reference so much, that mix before or after doesn't really matter. Getting on the loop sooner than later is more important than if you have a mouse fart of He in your mix or not. I just did a CCR course for a Prism, cross over for me, first CCR for the other three students. It was an air dil class, even though all three of them are mix certified on OC, and I'm normoxic CCR.

Not to be dickish, but were you teaching the class or taking the class while not being able to calculate END? If you are teaching that very skill, it shouldn't be difficult for you.

21/35 at 150' gives you an END of 86'. That isn't inconsequential, not even a little bit. It is the difference between safe and possibly not.

As to getting the helium, it is definitely iffy these days, but still possible with some digging.

 

[doctormike]

It's been a few years so I don't remember details. The shop banked 21/35 and that's what we used. I doubt they would do the same today with the current suppy issues. I'm not sure what complications would be involved by adding helium, though. It's less dense and easier on the scrubber, as well as being less narcotic, so what's the downside?

I guess no downside if there was no extra cost. I mean, a lot of my Helitrox course was about helium, but I suppose if you already were very comfortable with that, it doesn't really distract from the main purpose of MOD 1.

I was just more responding to the statement that MOD 1 should be done on trimix since you would be more clear headed and better able to learn CCR techniques. My feeling was that no one should be just figuring out all of the new stuff at depths where that would be an issue....

 

[Marie13]

I was just more responding to the statement that MOD 1 should be done on trimix since you would be more clear headed and better able to learn CCR techniques. My feeling was that no one should be just figuring out all of the new stuff at depths where that would be an issue....

That was pretty much my reaction when I found out that IANTD allows CCR instructors to teach Adv Recreational Trimix (aka Helitrox) to 150ft for Mod 1 for divers without any deco training.

 

[doctormike]

That was pretty much my reaction when I found out that IANTD allows CCR instructors to teach Adv Recreational Trimix (aka Helitrox) to 150ft for Mod 1 for divers without any deco training.

Yeah, maybe an IANTD instructor can chime in and explain that. Always happy to learn.

But IMHO, CCR really is very different from OC. I don't think that anyone should be doing deco or trimix depths until they have a significant number of hours on the loop after training.

 

[rongoodman]

I don't recall any deco during the course, and as I mentioned, "trimix depths" can be interpreted in various ways. We just happened to choose a normoxic mix for our diluent.