Diving air to 60m

[Germie]

I can carry 25 min at 60meters. You can twist my words all you like but that doesn’t mean I said I done 30 minutes bottom time on a 12ltr twin set. ( a dive which could be done if I pumped to 300 bar )I also said the notion that trimix is safer than air is a myth, its not possible for it to be safer to use multiple gases than a single gas.

You say now you also do deco on backgas? Because if you use decogases (60m is safer with 2 decogases, for sure with 25-30 minutes bottomtime), you have to do exactly the same gasswitches as you do while diving on trimix. The skills aren't changing.

 

[beester]

@Germie , totally agree with everything you say, except the CMAS (FFESSM) part. I have an FFESSM cert and next to that a Belgian 4 star CMAS cert (that allows me to dive to 90m on air, how about that... I never reached that depth... the max I've done on air is 75m).

Yes a typical French CMAS diver (3 start) can dive to 57m, but the reality is different. They typically dive the 35-50m wrecks (for example the cote d'azur, wrecks like the Donator, Le Grec, Rubis, Togo), where the deep part is really a bounce to return to more reasonable depths (40m)... typically done with 15Ls and a bottom time of max 15-20' (at avg 40m) and 10-15' deco on backgas. The wrecks that are deeper or where you don't have a lot of profile like the Ju88 or conger wreck (50m but avg also 50m) are not dived a lot. I've done all on trimix and air... and I have seen some crazy stuff on those wrecks, but they all come up with big stories to tell.

I don't know about accidents and risk, because I haven't seen any data on incidents in the FR med, but I wouldn't exactly use FR CMAS divers as a good example on how to conduct 40-60m dives

I do believe that if there was a way for students to experience hypercapnia and narcosis in a controlled, safe way that would certainly help and be a benefit in their training.

 

[almostDIR]

I also said the notion that trimix is safer than air is a myth, its not possible for it to be safer to use multiple gases than a single gas.

Air also contains multiple gases including Argon and Helium so I can see no reason why some more Helium cannot be added heh

 

[beester]

I can carry 25 min at 60meters. You can twist my words all you like but that doesn’t mean I said I done 30 minutes bottom time on a 12ltr twin set. ( a dive which could be done if I pumped to 300 bar )I also said the notion that trimix is safer than air is a myth, its not possible for it to be safer to use multiple gases than a single gas.

Doing a 25' dive at 60m, will give you 2 hours of deco on air (backgas), you'll be spending 75 minutes of that at 6-3m, half of your double set is gone after 25' at 60m and you don't have enough to do all your deco on backgas. Even diving super agressive USN tables, you'll be doing more than an hour of deco. Doing the same dive with deco gasses, you'll be out of the water after 70 minutes. I just don't believe you.

 

[Germie]

@beester there is nothing to agree or disagree with, it is the truth there . And yes, I have done all these wrecks also. On air and on trimix.
And don't forget the single tank solo bounces to 60m in France.
But I don't know any numbers or more accidents with such dives.
I hope every diver is a thinking diver.

Narcoses is something I never felt, never experienced, never had, I was immume for it till I started trimixdiving. So maybe this is the reason that airdivers never experience narcoses. I will not say you cannot dive to 50 or 60m on air. But if you decide to do it, there are some risks, be a thinking diver. And respect the divers who don't do that. I will never use at 30.2m any trimix myself, but if you want to do, I don't mind, I don't have to pay the bill. I hope you do the same if I decide to take my ccr and use a high helium diluent on that 60m dive.

 

[mafi]

I also said the notion that trimix is safer than air is a myth, its not possible for it to be safer to use multiple gases than a single gas.

It takes a good portion of ignorance to say the air is safer than trimix (at the depths we are discussing) in 2019.

But I can't even find words to describe a notion that would make one to double down on that statement after confronted with scientific facts from multiple people.

 

[Celt]

It takes a good portion of ignorance to say the air is safer than trimix (at the depths we are discussing) in 2019.

But I can't even find words to describe a notion that would make one to double down on that statement after confronted with scientific facts from multiple people.

Why can’t you understand that I’m talking about me, and no one else. From the very first post I said it was a personal choice.

 

[Celt]

You say now you also do deco on backgas? Because if you use decogases (60m is safer with 2 decogases, for sure with 25-30 minutes bottomtime), you have to do exactly the same gasswitches as you do while diving on trimix. The skills aren't changing.

But I only use air. I don’t make any gas change. I can carry all the air I need in a 12ltr twin set

 

[Germie]

@mac64 The problem is that you say it is safer than trimix. Same with doing all on backgas. This seems to be impossible and unsafe for sure. Yes you can decide for yourself to dive on air to 60m. I don't mind. Maybe I will do the same if I absolutely need to do that particular dive and there is only air available, I have done enough dives on air and trimix to know what I can expect when doing it and can make a choice based on my personal experiences. But I cannot imagine to do such a dive without decogas and I will never say that air is safer than trimix. It are the known facts and personal criteria that make the choice valid or not. But I also know divers that would never do it on air, simply because they already cannot do things anymore at only 42m. And this is repeating for them on every 42m air dive. So for them trimix is the only option deeper than 40-42m.

You can say that high helium trimixes are a waiste of the expensive rare helium, so use less please, but to state that air is safer, that is not true.

I don't think that any diver will ever say that air is the preferrable choice if the price for a trimix is only the price of a nitrox fill.

Are you a technical diver? Because you state you don't use any decogas?
And can you show a 25 minute bottomtime decoschema including gas consumption for your dive to 60m?
The argument you use air instead of several gases and no decogases means that seems like you don't know a lot of details about technical diving, or you ignore them. I am now really curious about your gasplan, consumption and decoschema for a 60m dive with 25 minutes bottomtime.

 

[mafi]

Correct me if I am wrong, You said you can do 25min at 60m. That's almost impossible on 12L twin 200bar.