Air strategy for 4-5 tank dive days?

[Oz Chris]

On a recent trip (Philippines) where we did a few 4 dive days we had the choice of Air and 32%.

We used 32% on the deeper dives where it mattered (max just over 30m), and Air on the shallower dives. That meant Nitrox on dive 1 in one location, and dives 1 & 3 in the other based on the way the ops scheduled the sites, Given the number of dives we were doing and the cost of Nitrox we we’re on the side of not using it unless it had an NDL impact. If it was free, the. I’d probably do at least 2 dives a day on it either way.

 

[AfterDark]

Although I'm nitrox certified I've found nitrox does nothing for me except cost more so 21% is the way I roll all the time. If it was offered free then I'd use it just to get my money's worth out the trip.

 

[Centrals]

The topography of the site is the main considering factor. As long as I can do multi-level ascend I would use EAN21.
On wreck then I might use the best mix to extend the bottom time if it is justified(time wise).

 

[BazzaB]

4 dives a day I would go for 32

 

[Jay]

if all depths are similar then first two on air, last two on nitrox.

 

[gopbroek]

I have done this schedule in Cozumel on number of occations and use EAN on just about every dive (except extended safety stops like Columbia shallows or Paradise). For myself I tend to go deep hunting for Lion fish so it becomes a balance between nitrogen loading and O2 CNS available on my computer. If I plan on not going below 100' then I will use 36, past 100' then 32. Meanwhile I keep track of the O2 CNS value remaining on my computer and if necessary throttle back on the plan if I am getting to close. The cumulative O2 tracking model on various models of computers seems to vary greatly so their is no one size fits all formula because not everyones computer calculates O2 off loading the same.

 

[Prop Joe]

Depending on computer and depth, My Aeris (just bought a Perdix) will be give me an O2 alarm if diving all EAN 32/36, four tanks a day, with HP 120's. I've done it a few times and it is about 6 hours of joy. You may want to dive a tank of plain air that first morning dive after a four tank EAN day. Watch your computer and try to stay warm. Take nice warm nap to get your core temp up any chance you get. I'm usually shivering after four tanks. Have fun, be safe, happy bubbles...

 

[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.

When I posted this, I did not realize the thread was in the Cozumel forum.

When I am in Cozumel, I use 32% on pretty much every dive, unless it is going significantly deeper than that MOD (111 feet). I do not understand the argument that nitrox does nothing for you. At Cozumel depths, it adds significantly to your bottom time, assuming you have enough gas to make use of that advantage.

 

[JohnnyC]

I don't really use nitrox to extend bottom times in Cozumel. I was well away from NDL's all week (closest was 20 minutes). I dive nitrox to add a level of conservatism to my dives, both on a single dive level, as well as due to the fact that I'm doing an extended amount of diving over the course of a week, sometimes 4 dives a day.

 

[Addicted2H2O]

I would say if you can get EAN 32/36 free, then go for it. Otherwise, it tends to be a bit expensive and for me doesn't really help much other than increasing NDL's a bit. Certainly has no effects of making me feel better or less tired after multiple dives like some people claim. Maybe it just doesn't effect my body that way or maybe it's a placebo effect for others. As has already been suggested maybe dive air and if you feel you're getting too close to NDL's, switch to EAN to extend them a bit. Do you first two dives each day on air and then EAN for the remaining dives. If budget allows of course.