the point of standard gases was quite literally for logistics of mixing and that ended up making for convenient ratios to use for decompression. You bank EAN32 and the balance is helium. It essentially fixes your ppO2 and ppN2 at a limit that you're OK with and you don't have to pp blend O2 which is super annoying. You bank EAN32 and EAN32 only, and you only have to boost a little bit of O2 for your EAN50 bottle and O2. Super convenient.
So, what do you do when you don't have standard gases? You have three choices
- Dive a close ish ratio based on ppN2, ppHe, and depth, then pray. This is probably what UTD would tell you to do since you're supposed to blindly follow the almighty AG with whatever his god-like ability to decompress is feeling these days
- Accept that you'll have to dive a computer with whatever algorithm closely mimics whatever version of ratio deco that AG is selling as snake oil these days and get over it since you believe in whatever nonsense that deco strategy is, which is in direct opposition to the state of the art in decompression research.
- Don't dive
Don't like it? tough sh!t, that's the consequence of pigeon holing yourself to something that isn't adaptable.
The irony with UTD's ratio deco is they want you to be a thinking diver that can adapt with the dive profile, the problem is you can't do anything if the mix is wrong because the ratio's don't work. You obviously have room with a point or two in either direction which isn't really going to make much of a difference, but if they're diving something like 14/33 *air over 33% helium*, then you really don't have anything that you can do if you're going to dive RD.
Your fourth choice is turn your brain on and realize that there is nothing wrong with diving a computer. The anti-computer thing is based on a time when computers were both unreliable, and didn't have any control over your ascent profile. If you want to or have to stay at some depth for extra time, the computer doesn't care, it will adapt and keep on calculating for you.