Air strategy for 4-5 tank dive days?

[horn34]

I don't normally dive more than 2-3 tank dives per day, but this next visit will be with a buddy who has limited dive days, so we're looking at 4 dives per day. I've read different air strategies here, but I really haven't found a consensus. Some people are just using air, some are alternating between air/nitrox each dive and some are alternating between 32 and 36. Those are the ones I remember, but there were other strategies as well.

Thoughts?

 

[boulderjohn]

It depends primarily upon the depths you are diving. If I were doing all the dives on a place like Molasses reef in Florida, with a range from 20-35 feet, I would probably do all air. If most of the dives were between 50-130 feet, I would use nitrox on every dive, and if I could, I would use the best mix possible for each dive. That is very unlikely, though, so I would go with what is available.

 

[JohnnyC]

If nitrox is available (which it should be), use nitrox. 32 and 36 are readily available.

 

[Seaweed Doc]

It depends: If there's a dive beyond nitrox depths (for what's available, anyway) I'd go with air first, then switch to nitrox for all subsequent diving. If there's a cost difference, I'd probably save the nitrox for later dives when residual nitrogen is likely to be highest.

Hadn't thought about it, but I could see using the current pressure group I was in to make the call for me, depending on planned dive profile.

 

[rabe]

it depends on the depth, but stay between 32 and 36 and you'll be fine

 

[Diver0001]

My thinking is that the gas mix doesn't make much of a difference if you're still diving to within the same margin of the NDL. EANx will give you longer NDL's but if you're not using that to create a bigger buffer then there is really no safety benefit.

One thing that I think *might* help is what a buddy of mine used to do. He would dive 32% and put his computer in Air Mode to create a bigger buffer. he had a policy to never dive deeper than 100ft and was fully aware of what he was doing but chose to do so anyway in order to create the buffer he wanted.

That said, he did this quite a while ago. These days some computers use GF so you can adjust the gradient factors in order to achieve the same goal and with more control and precision.

All of this is to say that just diving Nitrox isn't the answer. There's more to managing your tissue loading than that.

R..

 

[nodakdive]

I dive a very conservative computer (Suunto Mosquito) and dive 36% on 2nd and 4th tanks. First and third tanks are air. No concern with depth or down currents on wall dives that way. My computer stays happy doing this.

I should add that I'm diving AL80s. If you're diving HP120s, that would make a difference.

 

[divingjd]

HP120s, 32% for the first, deeper dive, 36% for subsequent dives. Sometimes 21% with a steel 80 for very shallow (15 FSW or less) afternoon or night dives. Really need to use the nitrox to get the extended time offered by the big
tanks.

 

[sinistar]

Why not just stay above MOD for EAN36 and just do all dives on 36%. In Cozumel you will probably spend 10% or less of your time below 90ft. At most another 10% between 80-90ft. Maybe 60% of your time between 40-80ft. The last 20% doing safety stops or putzing around shallow.

I've always wondered, if caught in a down current for say 1-2 minutes will 02 toxicity be an issue??? Otherwise that EAN36 might be darn nice to have as you ascend back up and do deco stops on the way back up. Maybe with the higher nitrox a deco obligation might even be avoided...or if it's blown, less likely to lead to a bad hit.

 

[nodakdive]

I've always wondered, if caught in a down current for say 1-2 minutes will 02 toxicity be an issue??? Otherwise that EAN36 might be darn nice to have as you ascend back up and do deco stops on the way back up. Maybe with the higher nitrox a deco obligation might even be avoided...or if it's blown, less likely to lead to a bad hit.

It probably depends on your mix and how deep the down current takes you. If it is "an issue", avoiding a deco obligation or a bad hit probably *won't* be an issue.