Do I need Nitrox?

[UB]

I have been doing some beach dives lately. My typically dive with the following profile:

~ 2hrs with a max depth of ~20-25ft
~ 1 hr surface time
~ 2nd dive at 2hrs with a max depth of ~20-25ft
~ Using tanks (80 cu ft) with air

My computer shows no problem with my nitrogen level (Aeris Atmos AI). I recently decided to check my tables and per NAUI's recommendation - for dives less than 40 ft I use the 40 ft table which indicated I exceeded the limits.

Should I switch to Nitrox to be safe?

Any feedback is appreciated

Thanks
UB

 

[Scubakevdm]

No.

 

[Skyjunky]

No

 

[ClayJar]

First, I am not a NAUI board member or anything, but that out of the way, I dare say that the reason the NAUI tables begin at 40 fsw is basically because they don't want to have as many letters as the PADI RDP.

Seriously, though, every instructor I've ever met had been of the opinion that if you're not at least *on* the tables (40 fsw), there's no reason to use EAN. Most of them wouldn't bother cracking a valve on their Nitrox tanks until they were at least at 60 fsw or so, at which point the equivalent air depth method would mean you get to hop up a full row on the tables (EAD of EAN32 at 60 fsw is 47 fsw, letting you use the 50 fsw row instead of the 60 fsw row). At a mere 20-25 fsw on air, even my conservative computer stops giving me finite NDLs, so Nitrox won't show any change to that.

For 20-25 fsw on EAN32 (Nitrox I, 32% O2), your equivalent air depth will be 13-17 fsw, which would basically mean that if you dove that depth on EAN32, the entire dive would be a safety stop.

That said, remember that you *are* under pressure, and even though you needn't worry about nitrogen loading when returning to the surface, staying under pressure for a very long time will mean your long half-life tissues will get a nice loading, and I wouldn't recommend flying or mountain climbing. (In fact, I've read that a short, deep dive is preferred to a long, shallow dive, if flying is in your near future. The short half-life tissues load up, but they offgas faster.)

 

[Blackwood]

I wouldn't dive those on Nitrox. The minor depths make it fairly unnecessary, so the cost becomes the main factor.

 

[spectrum]

Nice air usage too!

With a few assumptions I'm seeing something sub .40 for a SAC.

 

[diverryan]

I wouldn't dive those on Nitrox. The minor depths make it fairly unnecessary, so the cost becomes the main factor.

Exactly. If you were a bit deeper, then it might be as to some benefit but due to the shallow depths, cost becomes very important. Don't get me wrong, I prefer nitrox to air on any recreational dive but in your case, I see it as impractical. Just my 2 PSI.

 

[UB]

Exactly. If you were a bit deeper, then it might be as to some benefit but due to the shallow depths, cost becomes very important. Don't get me wrong, I prefer nitrox to air on any recreational dive but in your case, I see it as impractical. Just my 2 PSI.

Sorry if this seems like a stupid question - but what cost is everyone referring to? Do I need new equipment?

I am also considering starting to rent 100's or 120's (to further increase down time) which I can not find air rentals for. I seems the only rentals for 100's or 120's are Nitrox.

Thanks for the feedback.

 

[Web Monkey]

The cost people refer to is the cost of the Oxygen used to make Nitrox, which can add $5 or more to the cost of a fill, depending on the size of the tank and the %O2 you want.

Terry

Sorry if this seems like a stupid question - but what cost is everyone referring to? Do I need new equipment?

I am also considering starting to rent 100's or 120's (to further increase down time) which I can not find air rentals for. I seems the only rentals for 100's or 120's are Nitrox.

Thanks for the feedback.

 

[nolatom]

Nitrox is more useful at the depths where you're absorbing nitrogen pretty quickly, but not so deep that the increased oxygen (toxicity) becomes a concern. So in dives between, say, 60 to 100 feet, you'll see many divers using it. Many divers claim they feel better after the dives breathing nitrox than air--could be anecdotal, but maybe not.

At 20-30 feet, you're not really taking on nitrogen fast enough to need nitrox, you're fine on air. You'd be fine on nitrox, too, assuming it's the only thing available to rent, it's just not really necessary at those shallow depths.