Best Mix VS Standard Gasses (split from a GUE fundies course report)

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Messages
130
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Location
Augusta, GA
# of dives
200 - 499


A ScubaBoard Staff Message...

This thread is a split off discussion of differing opinions on best mix and standard gasses approaches to choosing mixes for different depths and conditions. It became far too involved in off topic discussion and since it is potentially valuable we have split off the discussion to continue here.

This first post was not part of the moved posts but was copied here to allow this modpost to have a timestamp that would place it as the first post in this new thread.

Enjoy your new discussion and note that it is in the Technical diving forum rather than basic scuba which is where the original thread resides
 
So when diving in a locale where He is't available, no diving??




What does that mean, irrelevant so don't use it or what?



What is the "wisdom" behind using a single mix and not using best mix, or close to it, if it is available and the diver is willing to mix it?
If you don’t have the right gear/gas/team/conditions, don’t dive.

Best mix quickly becomes a burden as soon as some dive parameter changes. If you choose a “best mix” and the dive shifts from the planned 80’ to 100’, you’re in a pickle.

Additionally, constantly shifting your mix makes it very difficult to memorize decompression times. I can easily remember NDL times for 32%. Can I easily remember them for 25%, 26%, 27% ......36%? No. This greatly simplifies dive planning.

Similarly, if I show up for a rec dive in south Florida with gue folk, I know everyone will have 32%. Everyone is on the same page without even having to talk about it. I can bring a spare set of tanks for a buddy. If someone adds on last second, no problem! It’s simple.

Standard gases are probably one of the biggest things for simplifying logistics, even on the most advanced dives.

Spinning your wheels with “best mix” to squeak out a few less minutes of deco or a few more minutes of dive time isn’t time we’ll spent, imo.
 
So when diving in a locale where He is't available, no diving??




What does that mean, irrelevant so don't use it or what?



What is the "wisdom" behind using a single mix and not using best mix, or close to it, if it is available and the diver is willing to mix it?

I took it as meaning someone who would dive to 130 on air does not have the correct mindset (to receive a GUE Tech pass). I infer no He, no dive to 130.

And, use of AI is not a factor in evaluating whether a person has the correct mindset (to receive a GUE Tech pass). Whether they use AI or not would not affect the evaluation. I'm guessing that whether or not they use a physical SPG would affect said evaluation, but that is just speculation on my part. I.e. No SPG == not correct mindset.

And, I was told that the entire point of GUE using Standard Gases is so that a team could come from all different places to meet at the dive site and dive and the only prior conversation (about gases, anyway) they would need is to communicate to everyone what the max depth would be. After that, everyone would automatically show up with the correct gases, with no further discussion.

Personally, if I'm facing the deco obligation that comes from using TX21/35 on a dive where I could have used EAN32 (e.g. a dive to 110'), I'm fine with taking the extra 2 minutes to agree on using EAN32. I'll probably make up for that 2 extra minutes by getting fills of banked 32% while someone else is spending even more time than that getting fills of 21/35.

But, I'm not going to begrudge anyone who wants to spend a few extra minutes hanging on deco in order to save a couple of minutes of dive planning. Dive and let dive.

Now that we have a GUE instructor who has confirmed that answers given in the final evaluation COULD affect whether a person gets their Pass or not, I'm wondering where @CptTightPants21 has gotten off to....
 
If you don’t have the right gear/gas/team/conditions, don’t dive.

Best mix quickly becomes a burden as soon as some dive parameter changes. If you choose a “best mix” and the dive shifts from the planned 80’ to 100’, you’re in a pickle.

I don't want to turn this thread into a Best Mix vs Standard Gases crapshow, but I cannot let this misinformation go with no response.

I dive OC using Best Mix. That means that, if I'm planning a dive to 80' but there is an alternate site that is 100' that we might end up going to, the Best Mix for me to take is the one that gives me my optimum ppO2 at 100'.

If we do the 80' dive, my gas will be just a little leaner than optimum. If we divert to the 100' site, my gas will be just fine.

This is in contrast to gas planning where you say "max depth is nnn, so I will take gas XYZ" and then have to divert to an alternate site that turns out to actually be deeper than you can use gas XYZ for.

If the plan is a dive to 100' and everyone shows up with EAN32, what happens if you divert to a site that is 110'? Or 120'? That could EASILY happen in NC diving. "Everyone just shows up without even having to talk about it" sounds like a good chance of not getting to dive. If everyone knows you might divert to a 120' site, does that mean everyone shows up with TX25/25 and uses that when you succeed in getting on your primary target at 80'? TX25/25 for an 80' dive?

I do not believe in shortcuts for dive planning that involve phrases like "this way I don't have to think about it." Not when it means things like "I don't have to think about what gas I'm taking." Knowing and discussing the site and the alternates and choosing a gas that will work for any of them is part of determining the Best Mix for the dive plan. And there is more benefit to that planning than JUST saving a few minutes of deco - in my opinion.
 
I don't want to turn this thread into a Best Mix vs Standard Gases crapshow, but I cannot let this misinformation go with no response.

I dive OC using Best Mix. That means that, if I'm planning a dive to 80' but there is an alternate site that is 100' that we might end up going to, the Best Mix for me to take is the one that gives me my optimum ppO2 at 100'.

If we do the 80' dive, my gas will be just a little leaner than optimum. If we divert to the 100' site, my gas will be just fine.

This is in contrast to gas planning where you say "max depth is nnn, so I will take gas XYZ" and then have to divert to an alternate site that turns out to actually be deeper than you can use gas XYZ for.

If the plan is a dive to 100' and everyone shows up with EAN32, what happens if you divert to a site that is 110'? Or 120'? That could EASILY happen in NC diving. "Everyone just shows up without even having to talk about it" sounds like a good chance of not getting to dive. If everyone knows you might divert to a 120' site, does that mean everyone shows up with TX25/25 and uses that when you succeed in getting on your primary target at 80'? TX25/25 for an 80' dive?

I do not believe in shortcuts for dive planning that involve phrases like "this way I don't have to think about it." Not when it means things like "I don't have to think about what gas I'm taking." Knowing and discussing the site and the alternates and choosing a gas that will work for any of them is part of determining the Best Mix for the dive plan. And there is more benefit to that planning than JUST saving a few minutes of deco - in my opinion.
If the plan was 100’ with alternates to 120, I’d simply shift to the next deeper standard gas of 30/30.

Too easy.
 
If the plan was 100’ with alternates to 120, I’d simply shift to the next deeper standard gas of 30/30.

Too easy.

I got to ask, how often do you dive trimix?
 
I was asked a direct question as to my opinion on certain situations, I answered. Life's too short to argue about it.

Who is arguing here? I am asking you a question to clarify your earlier statement because I am sincerely confused and needed clarification. If you are unable to respond and answer a very simple question that is genuine question in a professional manner why butt in the discussion in the first place? I live in part of the world where there is NO He available to use in anyway that is economical if available at all. (some hospitals import He in large storage bottles from overseas. When the bottle runs out of He, they throw the bottle away or use it for something else and then they have to import a new bottle with He from overseas suppliers).

I am extremely surprised and disappointed with your response and attitude.
 
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http://cavediveflorida.com/Rum_House.htm

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