OK got it. I'm all for clarity of the definitions, can only make the discussion easier. When calculating the gas in IANTD class, MOD and END were both considered, I didn't notice that "best mix" refers only to MOD. So you would say that both air and 21/35 are best mix at 56m (185ft) with pPO2=1.4. "best mix" is not limited to Nitrox, Trimix can be best mix, the term does not denote one particular gas because it says nothing about END and the He content. That's different from how I thought of it, but OK.
Best Mix VS Standard Gasses (split from a GUE fundies course report)
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Best mix trimix also includes the personal END. First you start with the max PO2 you want to use. And you have the MOD (AND TOD) That can be 1.4, but if you prefer 1.2, then this is right too. Then you take a personal END. With this, you get or an nitrox, or an trimix. In a nitroxcourse you learn the best mix for nitrox. In a trimixcourse you learn that you can choose a personal END and use MOD/TOD for the fraction O2 and then the END for the fraction helium.
Most divers use 1.3 or 1.4 as PO2 and max END between 30 and 40m.
Sometimes PN2 is used as max nitrogen partial pressure instead of END (but is more or less the same).
If you go to 135ft and dive air vs a nitrox, the NDL is 1-2 minutes longer on ean. If deco on backgas is done (not my favorite), then nitrox gives you a lower nitrogen loading. But the NDL is not really longer. Nitrox works best till 30-34m if you want to have longer NDL-times. Do you want to go deeper, take a decogas and do decompressiondiving. Stay within NDL will give bouncedives.
The earlier mentioned 45m dive with air, vs 21/35 vs best mix nitrox or best mix trimix: the deco differences are small if you do 20-25 minutes bottomtime. So there is no problem to have a best mix diver together with a 21/35 and an air diver. Easy take the most conservative diveplan and follow that.
Last week I was in Italy diving the Milford Haven wreck. We had a group of oc and ccr divers. I prefer diving a high helium mix on ccr as the cost difference is only 1 euro or so, even if I only go to 55m. So I had most times a 10/60 as diluent. I dove together with oc divers with 21/35 and the other ccr divers with different diluent mixes. No problem at all. Bailouts where till 70m 18/45, ean50 and 100%. The 21/35 oc divers used ean50. There where some decodifferences, but as they only could help 1 diver at once, the first that finished deco went up, the others waited on the decobar. At the end everybody had his deco done and nobody had to wait longer than needed.
Most divers use 1.3 or 1.4 as PO2 and max END between 30 and 40m.
Sometimes PN2 is used as max nitrogen partial pressure instead of END (but is more or less the same).
If you go to 135ft and dive air vs a nitrox, the NDL is 1-2 minutes longer on ean. If deco on backgas is done (not my favorite), then nitrox gives you a lower nitrogen loading. But the NDL is not really longer. Nitrox works best till 30-34m if you want to have longer NDL-times. Do you want to go deeper, take a decogas and do decompressiondiving. Stay within NDL will give bouncedives.
The earlier mentioned 45m dive with air, vs 21/35 vs best mix nitrox or best mix trimix: the deco differences are small if you do 20-25 minutes bottomtime. So there is no problem to have a best mix diver together with a 21/35 and an air diver. Easy take the most conservative diveplan and follow that.
Last week I was in Italy diving the Milford Haven wreck. We had a group of oc and ccr divers. I prefer diving a high helium mix on ccr as the cost difference is only 1 euro or so, even if I only go to 55m. So I had most times a 10/60 as diluent. I dove together with oc divers with 21/35 and the other ccr divers with different diluent mixes. No problem at all. Bailouts where till 70m 18/45, ean50 and 100%. The 21/35 oc divers used ean50. There where some decodifferences, but as they only could help 1 diver at once, the first that finished deco went up, the others waited on the decobar. At the end everybody had his deco done and nobody had to wait longer than needed.
CptTightPants21
Contributor
Think about that though. You have two separate dive teams doing the exact same dive. One team calculated gas using 1.4 and other 1.3, they can't both be diving best mix.
It's like doing a dive at 160 on 21/35. The standard gas for 160 IS 18/45. GUE divers have tables for at least 20ft deeper on each standard gas. GUE divers can and will do the dive using 21/35 for a variety of reasons--it's the gas they have available in their tanks, cost, conditions of dive site, maybe only part of dive is at 160', etc. Just because GUE divers are doing the dive at 160 on 21/35 does not change the fact that 18/45 IS the standard gas at 160'.
Best Mix is 1.4/total ATA. If you want to talk best mix trimix it is still 1.4/Total ATA and then it is how much END do you want. You mention it yourself that divers will calculate 1.2 or 1.3 or 1.4 and some will do END of 100 or 130. I have no problem with any of those choices, but you can't mix and match them and all call them best mix. There is nothing wrong with choosing a custom blend on a particular dive and saying you want 1.2 and 130 or 1.3 and 100. I feel like half this thread is driven by because people don't want to he accused of not diving best mix. It's just a name people!. If I have to go back in the history books i'm pretty sure it came about as 'best mix to extend bottom times and minimize deco' for a set dive.
In most courses there is told: PO2 max 1.4. But you can choose a lower one. So if you choose a lower one, this means best mix for your choices. Nothing more, nothing less.
In a team you agree with the team the best mix for the team members. Nothing difficult.
Best mix is a choice for the best safety and your personal END and PO2. So it is just how you interpret it. Safety can be a max PO2 of 1.3 or 1.2 also. Or a lower END of for example END max 24m like is done in the ART courses.
I use DIR and none-DIR things, just what is needed for the dive. So I can dive to 60m on 18/45, but for my money and my personal END (and PO2 max 1.4) a 20/25 also fits without issues. I prefer to use 2 decogases at 60m. 55m is a thing to think about and 50m I use only one. But most times I use CCR on trimixdives.
There are a lot of choices for what gas you want to use, same with best decomixes, do you prefer 100% or ean80 for example? DIR divers will say 100%, most effective. But you have to deal with airbreaks on longer oxygen stops, higher CNS (CNS is almost half on ean80), and the by some divers given argument that ean80 users cannot hold a 6m stop is completely ******** of course, that divers don't understand diving. I take what fits the best for my dive. Most times it is 100%, but sometimes ean80.
I have some tables with decogas ean70, but have never breathed it. haha.
At the end I see that 'DIR'-agencies are moving more and more towards the other agencies in ideas about technical diving. In 2011 eCCr was forbidden, also sidemount. Now you can do already CCR courses after T1 and sidemount is also teached. I allways said: take the tool that fits best for the dive.
I learned pragmatic deco a long long time ago (in combination with best mix diving) and in that time ratio deco and standardgases was the way to dive by 'DIR' agencies (I know gue rd is not same as utd rd, but both call it rd). Now you see a dive planned and pragmatised by gue divers also. I use rd as a tool to have fast an idea about the total divetime. At the end all divers have to deal with the same physics and there are no stats that say agency 'A' has less DCS cases than other agencies.
The most important thing is that every diver must be a thinking diver. And if you use your brains, then you can dive safe, with best mix and with standardgases.
In a team you agree with the team the best mix for the team members. Nothing difficult.
Best mix is a choice for the best safety and your personal END and PO2. So it is just how you interpret it. Safety can be a max PO2 of 1.3 or 1.2 also. Or a lower END of for example END max 24m like is done in the ART courses.
I use DIR and none-DIR things, just what is needed for the dive. So I can dive to 60m on 18/45, but for my money and my personal END (and PO2 max 1.4) a 20/25 also fits without issues. I prefer to use 2 decogases at 60m. 55m is a thing to think about and 50m I use only one. But most times I use CCR on trimixdives.
There are a lot of choices for what gas you want to use, same with best decomixes, do you prefer 100% or ean80 for example? DIR divers will say 100%, most effective. But you have to deal with airbreaks on longer oxygen stops, higher CNS (CNS is almost half on ean80), and the by some divers given argument that ean80 users cannot hold a 6m stop is completely ******** of course, that divers don't understand diving. I take what fits the best for my dive. Most times it is 100%, but sometimes ean80.
I have some tables with decogas ean70, but have never breathed it. haha.
At the end I see that 'DIR'-agencies are moving more and more towards the other agencies in ideas about technical diving. In 2011 eCCr was forbidden, also sidemount. Now you can do already CCR courses after T1 and sidemount is also teached. I allways said: take the tool that fits best for the dive.
I learned pragmatic deco a long long time ago (in combination with best mix diving) and in that time ratio deco and standardgases was the way to dive by 'DIR' agencies (I know gue rd is not same as utd rd, but both call it rd). Now you see a dive planned and pragmatised by gue divers also. I use rd as a tool to have fast an idea about the total divetime. At the end all divers have to deal with the same physics and there are no stats that say agency 'A' has less DCS cases than other agencies.
The most important thing is that every diver must be a thinking diver. And if you use your brains, then you can dive safe, with best mix and with standardgases.
CptTightPants21
Contributor
There is nothing wrong with making these decisions in a team, but this the sissy millennial definition of 'best'. You're the best...and you're the best.....and you're the best....
Why are you not calling the above the chosen gas for the dive, the custom blend, preferred gas.....I mean literally any name would work better than 'best mix'.
For me it is the same, haha. But most divers call it 'best mix'.
Call it easy 'mix' and it is all good
and it also includes 'standard gases'.
Ha ha!
I did! Want to, that is.But, I realized recently that since I'm diving CCR now and trying not to dive OC at all - certainly not any Tech on OC anymore - I think that Fundies is really not a good way for me to spend my time and money.
If I did take Fundies at this point, the only real point would be to learn and improve my OC skills and knowledge, and get a Tech pass, which affirms to me that I genuinely did demonstrate the requisite skills and knowledge. Now that I have learned that my current thinking would likely be deemed "not the right mindset" to receive a Tech pass, and the various GUE people here have not convinced me that I should limit myself to 100' without helium or 32% when shallower, I am highly doubtful that actually taking Fundies would have any different result. So, with this latest info, I am pretty convinced now that Fundies simply is not a good fit for me and my future plans.
If GUE starts to offer a Fundies for CCR (that would allow a rEvo), then I might consider it.
In the meantime, I will spend my time and money advancing my training (and, hopefully, my skills and knowledge) with my rEvo instructor.
victorzamora
Contributor
PfcAJ
Contributor
I'm glad you asked! I'm pretty passionate about my disdain for Rec 3.
Rec 1 is fine except its a very high entry barrier for someone who's never been underwater before. Rec 2 is maybe fine, has anyone even taught it?
Rec 3? HATE!
It's a doubles, deco, and trimix course.
Someone pass the bread, here comes the baloney!
Its taught to people who don't meet the Tech standard. Since they don't meet the Tech standard, it uses "ascent gas". You're not good enough to use a deco gas, so the course gives you a 3rd tank of bottom gas to ascend with. MAYBE, just maybe, instead of teaching a doubles, deco, and trimix class to people who aren't good enough to use all of those three tools, GUE should maintain its high standards and encourage people to improve themselves and their ability to reach that standard.
But AJ wait! What if someone doesn't feel they're good enough to take Tech 1? Or doesn't want to dive that deep! PADI limit is 130', why can't GUE have a 130' limit course?
If you aren't good enough to take Tech 1, maybe you shouldn't be doing technical dives? Crazy!
Tech 1 takes you to 150' during class. That's 20' more than the R3 limit. Twenty feet... that's like the width of two aisles at Walmart. Is that really the make it or break it for you? Again, if a diver isn't comfortable at 150', do you REALLY honestly think they'll be comfortable at 130'? They probably aren't comfortable at 150' because their skills and abilities aren't up to the Tech standard and they should go back to mastering that skillset.
WHO CARES what the PADI standard is?! I sure don't. The whole point is that GUE has a better curriculum and produces better divers than everyone else. That's the goal. Excellence, not mediocrity. Mirroring all the other unremarkable agencies reeks of mediocrity. The most remarkable thing about all those other agencies is the vast number of courses they offer and divers they certify. And the abysmally low standards. Yeah yeah, I know, SOME instructors out there are great. But on average? Nah. Not great.
And UGH that "ascent gas". If you're going to haul a 3rd scuba tank aorund with you, at least put something in there that gives you a real advantage. No technical diver would EVER use 32% as the deco gas for a dive with 21/35. Ever! Why? Cuz it doesn't provide you with any real advantage. Even more LOL is using 32% as the "ascent gas" from a 30/30 dive. 2% more oxygen, amazing efficiency! Yeah right. Barf.
I love GUE. A lot. I think that its the best in the game. But Rec 3 smacks of unbridled mediocrity and pandering to the lowest common denominator. I believe that GUE should lift people up by demanding the highest of standards, not lower itself to the creation of classes to cater to people who can't or won't meet those high standards. Lead, not capitulate.
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