Mixed buddies (air/Nitrox)

[L13]

I generally always dive nitrox and try to avoid diving with people who are on air (unless they are students). When with students, I’m on nitrox for the safety side of it and increased conservatism (diving Nitrox using Air tables). When I am fun diving, the problem with being paired with an AIR diver is they are going to shorten my dive. Depending on depth, their NDL is going to be much shorter than mine and they are going to need a longer surface interval. It is a mismatch. There have been times when I‘be been Instabuddy with someone on a drift dive and they are at NDL after 30 minutes and I still have plenty of time and more than half a tank. If I pay for a dive, I want my full dive, which is generally about an hour.

If you are diving Nitrox using air tables, your NDL is the same as the air divers. If you are taking advantage of the longer NDLs or shorter surface times for Nitrox, then you don't have increased conservatism. Which is it?

 

[covediver]

If I had an out of air situation on the third dive, I doubt I would be making a fourth. Prudence would dictate termination of the diving day.

 

[Umpman]

If you are diving Nitrox using air tables, your NDL is the same as the air divers. If you are taking advantage of the longer NDLs or shorter surface times for Nitrox, then you don't have increased conservatism. Which is it?

When I dive with students, I still have Nitrox but I use air tables. When I am fun diving, I use Nitrox tables and wont dive with someone on Air. My point was I ALWAYS dive Nitrox and the only time I will dive with someone who is not on Nitrox is when it’s a student.

 

[Scott G. Bonser]

Is there an issue if two divers are using different gases in their tanks on a dive? For example one has air, one has Nitrox and an out of air event or some other catastrophic failure requiring shared air.

Going a step farther if the answer above is no, what if there are 4 dives planned for the day, two have been successful. On the third dive, the Nitrox diver has the failure and goes over to air. Failure occurs close to air NDL, but we'll short of Nitrox NDL. Should the 4th dive be scrubbed by the Nitrox diver?

Are there any times you can think of where pairing a person on air with a person on Nitrox should or shouldn't be paired together?

I also struggled with whether to put this in basic or advanced...

…interesting point, SA. Now w/all this mixed gas diving…which should be safe, it may be something to consider. Perhaps a familiar individual will respond.

Scott G. Bonser

 

[Scott G. Bonser]

@SATurner , it isn't that uncommon, I've done it many times. Just follow what @Gareth J said, and you are good.

The NDL thing applies not just to Nitrox/Air but also to dive computer algorithms, conservativeness settings/GF's, previous dives, etc. The most limiting NDL of any buddy of a buddy team is the limiting NDL of the whole team, regardless of the reason. He is not your buddy if you are not limited by his NDL as well as yours, and vice versa.

Pre-dive check…..buddies communicate…then plan/adjust dive(s) accordingly.
Scott G. Bonser

 

[LFMarm]

I don't see a problem as long as you follow the most conservative profile of the 2. I am regularly diving in mixed teams CC and OC