Sidemount and nitrox mix

[p2diver]

Hi,
So I have benn diving sidemount configuration for over a year and love it.
Now I am going to do charter diving for a wreck( square profile): first 130'' and then second 80''. So the question is: Can this be dane on one EAN mix?? Pros vs cons!!
thanks
p2

 

[ffdiver]

I don't think you should have an issue answering this question if you were nitrox certified. Maybe i'm just reading the question wrong, but what does this have to do with Sidemount?

 

[scuba127]

I use 28% Nitrox for dives at 130' which requires an Advanced Nitrox Card to obtain the gas.....so, yeah, if at all possible I'd use nitrox for the 130' dive in order to increase bottom time....

 

[Jim Lapenta]

Why would you need an advanced nitrox card for 28%? The std recreational nitrox card should be good for any mix from 21% to 40%. Advanced nitrox is usually only required for mixes above that.

Of course if the class only covered set your computer to this and go you would not have the knowledge of how to calculate best mix, mod, ead, and know that you don't need to dive only 32% or 36%.

That's one way a shop could talk you into taking an adv nitrox course when you don't really need it.

What you should do is plan for the bottom, determine your best mix, and go with that for both dives. In doing so you need to decide what is the max ppo2 you are ok with. Personally I try to max at 1.3 for the working portion of the dive and adjust from there given the difficulty factor I may also need to figure in. Cold, current, amount of physical labor that may be involved, etc.

Stating a definitive mix for you would be unwise since I do not know those factors for your dive, your physical status, and what limit you are ok with.



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[WB2GLP]

Thanks, Jim. I was about to post the same reply. I've never had to submit a dive plan prior to a dive.

 

[DevonDiver]

Kinda a basic question from a nitrox-use perspective unless the OP meant that he intended to use two sidemount tanks over two dives (the same tanks both dives). Asking whether it'd be appropriate to carry a different mix in each tank - one optimal for the first dive, the second optimal for dive #2.

If that were the question, I'd say it'd be more optimal to carry the same gas in both tanks (28%), accepting a less than optimal mix for dive #2 in lieu of the benefit of retaining simplicity, tank balance and gas redundancy/access on dive #1.

As I remember it, Advanced Nitrox used to be/is the necessary training to safely plan and conduct multiple different gas mixes on the same dive (even if <40%). That has no bearing on obtaining any mix <40% though...

 

[chrpai]

As I remember it, Advanced Nitrox used to be/is the necessary training to safely plan and conduct multiple different gas mixes on the same dive (even if <40%). That has no bearing on obtaining any mix <40% though...

Let me first say that I assume very, very, very few recreational divers do this. That said, I'm equipped to do it since I have an LP95 and an AL40 and I could put different mixes in them. I could use my Hollis DG03 to switch between them as well. Can't say I've ever felt the need though.

Let's say I didn't have the DG03 though. Why would I need an "advanced" nitrox cert to do this? Nitrox is nitrox. When I switch tanks the only thing that changes is my MOD and my EAD.

I'm with Jim. I've always heard of "advanced" nitrox being for 41%+ in the context of AN/DP.

 

[DevonDiver]

Why would I need an "advanced" nitrox cert to do this? Nitrox is nitrox.

As far as I'm aware, the basic nitrox course doesn't teach gas switching procedures: A protocol for ensuring that you don't switch onto a gas inappropriate for your current depth (the leading cause of technical diving fatalities, I was told).

When I switch tanks the only thing that changes is my MOD and my EAD.

Kinda the point...

First - I'm not expressing a personal opinion on this. This is what I remember from my TDI Advanced Nitrox many years ago...

Second - Recent introduction of sidemount training into the mainstream does serve to make divers more aquainted with reg switching, but not gas switching.

Third - One assumes a diver would carry two different nitrox mixes to make optimal use of the nitrox at two different depths on the same dive. Thus the diver would be taking one of those mixes below its MOD.

 

[p2diver]

Thanks so far for a input. Sorry for not being clear about all the information on my last post. I am planning to do those dives on the same tanks if possible. 2 HP 100 steels in the Great Lakes (cold fresh water). For 130 ft with ppO2 1.3 mix will be 26 but for 80ft is 38. So how do I adjust the mix when doing sidemount?

 

[Jai Bar]

Thanks so far for a input. Sorry for not being clear about all the information on my last post. I am planning to do those dives on the same tanks if possible. 2 HP 100 steels in the Great Lakes (cold fresh water). For 130 ft with ppO2 1.3 mix will be 26 but for 80ft is 38. So how do I adjust the mix when doing sidemount?

Are you going to take along only two tanks to be used for both dives- no refilling between dives? In that case, I'd probably do both on ean32 and be done with it. Otherwise, I'd use ean36 for the second dive.

In my opinion the difference between 36% and 38% is not worth the hassle...

Yes, I'm aware 32% at 130' yields ppo2 of 1.6, IMO for a single day of diving it's fine- that's what I usually dive...

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