Is Open Circuit Trimix dying a slow death?

[Stoo]

I did some mix diving this summer for the first time in a while (Nice new wreck in 220', just down the road!). Having dropped about $1000 on gas just for those dives, a RB justification would be easy to make if a guy was going to do much of this. If I was 20 years younger, I'd be all over a RB, but not at age 63. I probably shouldn't be doing those dives anyway!

Sure is a pretty wreck though.

 

[JonG1]

I regularly get well and truly outdived by a septugenarian on my regular boat, you have years ahead of you Stoo.

Nice pic.

 

[Stoo]

I regularly get well and truly outdived by a septugenarian on my regular boat, you have years ahead of you Stoo.

LOL... Oh I'm not giving up anytime soon, but common sense suggests 200+ footers in 3°C water may not be wise at 63. But then common sense has no place in diving anyway.

And thanks... She's a pretty old boat.

 

[broncobowsher]

I’ve seen a 30%-40% drop off in OC Trimix fills at the shop in NJ over the past eighteen months.

I would like to stretch the question a little further, how much increase in rebreather trimix fills have you seen? Is it just an overall reduction in technical diving or a transition to rebreathers. How about heading out on the boat with the people who are getting these fills. Are the doubles just going away, or are they transitioning into rebreathers.

My introduction to Helium was via a rebreather. But I also bought a booster so I don't stop in dive shops for trimix either. I do still go in for air fills although I have yet to do an OC dive in almost 2 years now. I need the air for home blending and for boosting in a parking lot.

A rebreather is very forgiving for having the wrong mix. Planning on a 200' dive but arrive and conditions suck too much and more to a 150' spot that is good? With doubles you are not really going to be able to use the gas to it's potential, and it adds a lot of expense since you have so much excess helium. rebreather, runs the same setpoint. A little extra helium for the depth, only a few extra dollars.

Cells are an expense for a rebreather you cannot get away from. And sorb. Logistics for sorb can be one of the more challengine parts with diving with a rebreather.

 

[rjack321]

Logistics for sorb can be one of the more challengine parts with diving with a rebreather.

Why do you say this?
I have not had issues getting or shipping sorb anywhere. But my international travel is mostly limited to Canada

 

[taimen]

I couldn't find buddies, let alone regular teams, to dive OC tech with me. Thus a rebreather. I probably wasn't just me being a stroke, as the rb buddies have been really welcoming. But the cost of helium is not the only reason why active tech divers switch to rebreathers. I enjoy diving rb more than oc on profiles that are not overly complex to do with oc. The feeling underwater is one thing. Easier logistics during the weekends is another.

 

[CAPTAIN SINBAD]

What about those who are going into caves? Do we see CCRs replacing OC in cave diving as well?

 

[helodriver87]

What about those who are going into caves? Do we see CCRs replacing OC in cave diving as well?

Nah, not really. Deep cave, sure, but nitrox is cheap. OC cave diving in the recreational depth range is alive and well.

 

[rjack321]

What about those who are going into caves? Do we see CCRs replacing OC in cave diving as well?

The VAST majority of cave dives are done on OC at <100ft depths. There are more OC nitrox cave dives done at Ginnie in a month than all the cave trimix dives across the entire state of FL in a whole year.

In MX there is plenty of exploration being done on OC. But its super shallow there and you can do hours and hours with a 2 stage nitrox dive and not even have any deco.
Pretty much everywhere else the only cave exploration you are going to do is on CCR, usually with trimix.

 

[JonG1]

What about those who are going into caves? Do we see CCRs replacing OC in cave diving as well?

Not strictly cave but in the UK mine scene I have seen more CCR than OC recently despite relatively shallow depths, less than 30m mostly. But there is a fair bit of percolation so arguably a better choice.

Plus the cold, choice of exits if it goes tits, bad gas in air spaces etc.