Deco dive with divers on different back gas

[LFMarm]

I prefer everyone to program the gas they actually have — in case of an emergency you want to know what’s your risk exposure which will be different between air and EAN32.

I also prefer the whole team to dive the same gases so that everyone has the same plan and bailout.

In this case you should look at the diver with the most limiting plan and have all others follow that plan. This is discussed before the dive and during the dive the diver with limiting factors should be the one calling it if all goes well.

 

[Badger7]

Why? How is EAN different then trimix in that scenario?

Increasing oxygen and reducing nitrogen doesn't make a gas mix significantly less narcotic at depth, it just reduces nitrogen absorption rate into soft tissue. Adding helium and reducing either oxygen or nitrogen % (or both) actually makes the mix less narcotic to breath at depth.

 

[arkstorm]

The Trimix diver accrued similar deco obligation to the air diver based on the plan (35m/30min).

But in the OP's scenario, the EAN32 diver has less deco obligation on that dive, so why would that be a problem?

 

[grantmac]

But in the OP's scenario, the EAN32 diver has less deco obligation on that dive, so why would that be a problem?

I'm not saying the dive is impossible, but EAN simply isn't expensive enough to not bring when it makes sense.
I say that as someone who does rather a lot of air diving.

I definitely wouldn't have the EAN diver run their computer in air mode (gross).

 

[boulderjohn]

Although it is always best to have teammates as near to identical in gas, if you find yourself in this situation, it is not all that hard to deal with. The solution actually applies to all deco dives, even when the gases are as closely matched as possible.

• Don't lie to the computer. If you have 32% in the tank, that's what you put in the computer.
• Once you begin the ascent, you stay together. If one diver's computer says it's time for a stop, you both stop. There is no harm to the diver who does not have to stop--the computer will adjust to the extra stop, just as it would on any other dive.
• Once you are doing a stop together, you ascend to the next stop when both divers are ready for it. Again, there is no harm to the diver who is staying a little longer.

 

[NothingClever]

The EAN32 diver agrees to put their computer in air mode…

Why does the EANx diver agree to do this?

What prevented the air diver from drawing a better gas?

 

[boulderjohn]

What prevented the air diver from drawing a better gas?

What difference does it make? Evidently it happened for some reason, and the OP wants to know what to do about it.

 

[Wibble]

Different gases will mean different deco obligations, all other things being equal.

So, your mission, should you choose to accept it...

1. Spend the extra time with your budgie at the deco stop. Generally considered good form.
2. Wave goodbye and leave them at their deco stop, get back on the boat and eat all the good biscuits whist the other diver ponders why they were a cheapskate and had to do more deco when they could have had more bottom time.

There could be a third option: wave goodbye to them on the bottom as their TTS was much higher than yours and spend more time on the bottom.

 

[rjack321]

What difference does it make? Evidently it happened for some reason, and the OP wants to know what to do about it.

And you all keep going on about janky work arounds instead of just saying "nah not diving today". That's what both should do about it instead of asking strangers on the internet. It's a sloppy slippery slope which they already started with this purported 'plan'

 

[boulderjohn]

And you all keep going on about janky work arounds instead of just saying "nah not diving today". That's what both should do about it instead of asking strangers on the internet. It's a sloppy slippery slope which they already started with this purported 'plan'

Boy, I just don't see it as that big of a deal. If I had a buddy who had doubles filled with air and I had doubles filled with 32%, I'd do the dive. It's a pretty simple basic deco dive. I don't see why people are getting their panties in a wad over this.