Deep Air Dives In Tech Classes

[toby43]

I took TDI Extended Range, which is basically deep air. All it really did was confirm to me that I don’t like diving deep without helium.

There are some places where helium is unavailable or cost prohibitive. Most AN/DP courses do not require helium so for a lot of people it’s not even on their radar unless the instructor makes the student aware that it’s an option.

Worth doing Extended Range (TDI agency) to 55m on air, just for the experience. Also it gets you used to handling two stages at lesser depths without wasting money on helium as precursor to doing Trimix. Its a good combo.

 

[Germie]

Let's say it different. I talk now about a holiday, not teaching, just fundiving. What if a divecenter wants you to dive deeper than 30m on trimix? I move to another divecenter. I decide myself what gas I use. I normally don't even consider helium on dives shallower than 45m on my private dives (OC). If others in the team want to use helium on dives deeper than 40m, I do same. But than it is my choice. It is the team or myself. No outsiders who say you must use this gas. Same with others respect the choices of people, but don't tell it as only truth.
I talk here about the limits of air in the agencies (55-60m). Deeper is always trimix in my eyes. But even then an END of 35-40m can be applied with a reason.

Standardgases use a lot of helium and sometimes it is fine to use less helium with a higher END (or even no different in max END according to DIR, but save some money on the dive, 18/35 instead of 18/45 on a 55m dive for example, everything is within DIR rules, even ration deco can be applied).
I am personally a fan of bestmix. I teach both (standardgases and best mix), but normally I always use a best mix.

 

[LiteHedded]

I guess it depends on what turns your crank. I still make a fair number of dives with incursions >40m up to about 50m or a little deeper on air. They're pretty trivial dives in terms of the work involved but I actually choose for that. I'm trimix trained but I don't do drugs or drink and the narc is, I will admit, kind of the goal of some of those dives.

That said, it's unpredictable. Sometimes I'm fine at 50m and sometimes I'm pretty bonked at 36m. There's no telling how you'll feel until you get there so we always account for turning the dive early.

I've done many hundreds of such dives over the years. I'm not going to suggest that it's for everyone but just blanketly stating that it's stupid unless you are poor is kind of insulting to anyone who chooses for it and to anyone who is poor.

R..

No it’s stupid even if you are poor

 

[tomfcrist]

No it’s stupid even if you are poor

Have you been to 160fsw on air?

I’d argue that there are conditions benign enough on some days and sites that make it “not stupid”. Not ideal would be a better description.

 

[mdax]

I used to dive deeper on air when I was younger, it was dumb then and it still is nowadays.
At least then trimix wasn't as available.

Seems to me if you can't afford trimix for >150' dives you are taking too much risk using air.
Some folks like to base jump, others raise cobras as pets, knock yourself out, just don't include me.

If you do lots of diving >250' you need to purchase a rebreather, it's not elitist, it's logical.

 

[LiteHedded]

Have you been to 160fsw on air?

I’d argue that there are conditions benign enough on some days and sites that make it “not stupid”. Not ideal would be a better description.

Lolno

 

[Germie]

160 ft on air I do a couple of times a year. Not because of costs, but because of not too deep for me to do this 'just' 48.7m on air. If I think it is too deep, I take my ccr and always have a 6/72 diluent ready (poormansmix ), or whatever I have topped up that fits the dive. 160 ft on air on oc is within my holidaylimits.
I have done 200 ft on air also. That is quite deep. But it was a 'trydive' to try what is possible. I layed lines at that depth, did a bottle rotation, all without problems. I have done the same with air diluent (onboard, offboard a trimix if I got narked).

200 ft on air is still normal in a lot of places. Has nothing to do with no money, but with what is teached (cmas allows 200 ft on air for 3* divers) or no helium available.

I agree that 160ft is 'not ideal' maybe. But same with a 30/30 mix on a 30m dive. Or at 31m a 21/35. Helium is rare. Then a nitrox fits better.

But what I said before: discuss it with your team and then decide. Sometimes it has nothing to do with money, but with availability, or with standards of your agency. My choice of helium vs air has to do with responsability. Private vs teaching. If I have to take a diver on air for the first time to 160ft, then it is not only the air, but maybe a nervous student who never has been soooo deep. Then it is much better to be clear as instructor and have a not narked student who only have to be nervous about his decoschema and not about getting narked or not.

 

[LiteHedded]

160 ft on air I do a couple of times a year. Not because of costs, but because of not too deep for me to do this 'just' 48.7m on air. If I think it is too deep, I take my ccr and always have a 6/72 diluent ready (poormansmix ), or whatever I have topped up that fits the dive. 160 ft on air on oc is within my holidaylimits.
I have done 200 ft on air also. That is quite deep. But it was a 'trydive' to try what is possible. I layed lines at that depth, did a bottle rotation, all without problems. I have done the same with air diluent (onboard, offboard a trimix if I got narked).

200 ft on air is still normal in a lot of places. Has nothing to do with no money, but with what is teached (cmas allows 200 ft on air for 3* divers) or no helium available.

I agree that 160ft is 'not ideal' maybe. But same with a 30/30 mix on a 30m dive. Or at 31m a 21/35. Helium is rare. Then a nitrox fits better.

But what I said before: discuss it with your team and then decide. Sometimes it has nothing to do with money, but with availability, or with standards of your agency. My choice of helium vs air has to do with responsability. Private vs teaching. If I have to take a diver on air for the first time to 160ft, then it is not only the air, but maybe a nervous student who never has been soooo deep. Then it is much better to be clear as instructor and have a not narked student who only have to be nervous about his decoschema and not about getting narked or not.

but you don’t ever have to do that...

 

[tomfcrist]

Ok folks, discussion is over...the GUE dogma guys are here...we all know you need at least 35 percent helium unless you are diving in your pool.

 

[LiteHedded]

Ok folks, discussion is over...the GUE dogma guys are here...we all know you need at least 35 percent helium unless you are diving in your pool.

I didn’t say that. And the bulk of my training is with iantd.

If you think you have to take people that deep in air you are mistaken. You don’t.