Cheaping out on Trimix - travel gas

[kensuf]

A couple of months ago we were diving with a lot of gue divers. Most of the divers were tech 1 oc divers. They were using a set of doubles with ean32, 21/35 stage and oxygen stage.

I was in a team of gue ccr divers. We had a dpv and a oxygen stage.

After visiting 2 wrecks at 35 meter the oc divers were switching from their trimix stage to backgas. It was really a mess, the tech 1 divers could not handle 2 stages and dpv. They were loosing their buddies, bouyancy was screwed up.

Adding more gear doesn’t always solve problems…

I'm struggling to believe that GUE Tech 1 trained/certified divers were diving EAN32% in their doubles and stages of trimix. I realize/understand/acknowledge that 32% at 35m isn't blowing MOD on PO2, but having your bottom gas in stages and having a shallower gas on your back was at one point in time a direct violation of "DIR" practice.

 

[PfcAJ]

ITT: People who can’t afford to do the dives they want to do so they take obvious shortcuts re: END and gas density.

None of us can afford to do all the dives we want (I doubt many/any scubaboarders are just independently wealthy captains of industry). There’s nothing wrong with that. Save your nickels for the cool dives.

 

[CptTightPants21]

I'm struggling to believe that GUE Tech 1 trained/certified divers were diving EAN32% in their doubles and stages of trimix. I realize/understand/acknowledge that 32% at 35m isn't blowing MOD on PO2, but having your bottom gas in stages and having a shallower gas on your back was at one point in time a direct violation of "DIR" practice.

I 100% believe it. We are talking about a 117' dive. 32% would still be within 1.4 - 1.6 PPO2. I would just use nitrox on this dive, but if you were to use helium this would be the most cost effective way to do it.

 

[kensuf]

I 100% believe it. We are talking about a 117' dive. 32% would still be within 1.4 - 1.6 PPO2. I would just use nitrox on this dive, but if you were to use helium this would be the most cost effective way to do it.

But it's a method that's anything but DIR and the mindset behind "deep bottle will be mix, shallow stuff will be in my doubles" is dangerous.

 

[CptTightPants21]

But it's a method that's anything but DIR and the mindset behind "deep bottle will be mix, shallow stuff will be in my doubles" is dangerous.

Specifics and proportionality matter. This isn't a dive to 140' and 32% is in back gas. What if this was an example of doing a dive to 180' and they had 18/45 in the bottle and 21/35 in back gas? Maybe to save money or maybe because they had the 21/35 tanks filled already and wanted to burn the gas.

18/45 is clearly better, but it would be a mistake to say 21/35 can't be used in a pinch for this dive.

 

[Jack Hammer]

Specifics and proportionality matter. This isn't a dive to 140' and 32% is in back gas. What if this was an example of doing a dive to 180' and they had 18/45 in the bottle and 21/35 in back gas? Maybe to save money or maybe because they had the 21/35 tanks filled already and wanted to burn the gas.

18/45 is clearly better, but it would be a mistake to say 21/35 can't be used in a pinch for this dive.

But that's not what allegedly happened and even so your example's still not a great way to do things.

 

[barth]

what do they use the 21/35 stage for? extra gas or bottom gas?

They did use the trimix stage at the 35 meter wrecks and they did use the doubles with ean32 in the 0 - 30 meter range.

It's at least 400 meters of swimming to the wrecks. Sometimes the line to the wrecks is damaged. It can 20 minutes or more to find the line to the wrecks. They didn't want to waste trimix at shallow depth.

 

[barth]

I'm struggling to believe that GUE Tech 1 trained/certified divers were diving EAN32% in their doubles and stages of trimix. I realize/understand/acknowledge that 32% at 35m isn't blowing MOD on PO2, but having your bottom gas in stages and having a shallower gas on your back was at one point in time a direct violation of "DIR" practice.

I was not in their team. They told me if there was an issue they would accent to 30 meter, it’s just 5 meter. And they wouldn’t die breathing ean32 at 35 meter. But I think a lot of them agree that there are better solutions. A lot of the divers who were on oc during that dive will buy a JJ ccr…


But I agree with you, I don't like trimix in a stage and doubles with ean32...


It was to much taskloading, 2 stages and a dpv for tech 1 & dpv1 divers with not that much tech dives and dpv experince. If there is also bad visibility and problems then it’s to much to handle for them…

 

[kensuf]

Specifics and proportionality matter. This isn't a dive to 140' and 32% is in back gas. What if this was an example of doing a dive to 180' and they had 18/45 in the bottle and 21/35 in back gas? Maybe to save money or maybe because they had the 21/35 tanks filled already and wanted to burn the gas.

18/45 is clearly better, but it would be a mistake to say 21/35 can't be used in a pinch for this dive.

It's about normalization of deviance.

 

[jale]

They did use the trimix stage at the 35 meter wrecks and they did use the doubles with ean32 in the 0 - 30 meter range.

It's at least 400 meters of swimming to the wrecks. Sometimes the line to the wrecks is damaged. It can 20 minutes or more to find the line to the wrecks. They didn't want to waste trimix at shallow depth.

Frankly, for this particular situation, the gases choice, to offset a logistic and financial case, is not that bad.
The only problem is the mess with the equipment.