Nitrox for shallow water artifact diving??

[Belzelbub]

Apart from the fill being a little more expensive, there is no downside to using EAN on relatively shallow dives. There may or may not be a benefit.

I use EAN on all dives where I pay for fills. Most of those are under 60’. I believe I feel better after a dive using EAN, though I realize there isn’t empirical evidence to confirm the effect. The only dives I do on air are at an aquarium. Max depth is 15’ or so. I tend to feel pretty tired after those dives, but that could also be due to the dives being long, and I’m generally working the whole time. Aquarium provides air and tanks, so I’m not able to use EAN to compare.

I’d say give it a shot. Try it out, if you feel better after, then keep using EAN. If not, switch back to air.

 

[Esprise Me]

I found the Nitrox course really interesting and educational; it helped clarify some concepts we rushed through in OW. So I think it's worth taking if it doesn't mean sacrificing something more valuable to you.

I'm skeptical of the idea that diving Nitrox makes you less tired. I once tore the wrist seal on my drysuit while gearing up for the first of 3 boat dives, and didn't have a spare, so I was stuck not diving at all. I'm always tired after a day of boat diving, but this was the first time I fell asleep on the way back. So I'm pretty sure my tiredness has everything to do with the early departures and nothing to do with nitrogen stress. But as others have said, aside from the price, there's no downside to trying.

 

[AfterDark]

It is true that there is theoretically no limit for dives to 33 feet or less, but that does NOT mean there is zero decompression stress from the dive(s). Nitrox will most definitely reduce the nitrogen absorption and degree of supersaturation experienced by the diver. The question is: is it significant enough to matter?

For example, my little spreadsheet says diving 36% at 40 is equivalent to air at about 26 feet.

The nitrogen absorption above 33FSW is for all purposes zero. A SS can be anything above 33FSW, since the body is off gassing above 1ATM.
Air at 26FSW has no NDL, reason no nitrogen absorption.

 

[johndiver999]

Nitrogen supersaturation will occur with a dive to 5 feet for 5 minutes on air. I think my comments are more aligned with the physics of the situation, but I don't think I can add anything more pertinent to the discussion.

 

[lowwall]

The nitrogen absorption above 33FSW is for all purposes zero. A SS can be anything above 33FSW, since the body is off gassing above 1ATM.
Air at 26FSW has no NDL, reason no nitrogen absorption.

That's not correct. You have nitrogen absorption at 1'. There is no deco limit because the amount of excess nitrogen even when fully saturated at those depths isn't enough to cause problematic bubbles when you return to surface pressure.

 

[Wibble]

Maybe not related... I dive outside of NDLs and generally do 30 to 60 mins of decompression, sometimes more. Most dives are in the 30m-50m/100'-165' range. A typical 30m/100' dive would be for an hour's bottom time and 30mins of deco. The deeper dives would extend the deco.

I found that following many of these dives I was getting exceedingly tired to the extent that driving home would be difficult and may need a stop to grab some kip.

I changed my decompression last stop from 6m/20' to 3m/10'. As I dive in the sea, I rarely deco out as shallow as that, but I do -- if conditions allow -- ascend to 5m/16' or 4m/13' for a substantial part of the final deco. I also try to be extremely slow when ascending after deco's cleared, trying to do 1m/3' per minute ascent.

I've found that this substantially helps my post-dive fatigue.


I wonder if your shallow but long dives are showing signs of the same sort of thing I experienced? Are your final ascents fast or slow? It might be worth while doing an extended safety (deco) stop prior to surfacing.

 

[kelemvor]

Nitrox makes a huge difference in fatigue for me. I use nitrox for every single dive unless it's going to be deeper than 187' . It's not that nitrox gives you energy like caffeine or something. It's more like after a day of diving on air, I'd be pretty tired and worn out. After a day of doing similar dives on nitrox, I'm not tired or worn out.

You're only talking about a few dollars difference per tank (at least that's the case at my LDS). Try it and see if you like it. If you don't have a nitrox card, unfortunately you'll have to pay someone for a class. The reality is that what you need to know could easily be just a page in the OW manual, and an hour or less of class time.

At most shops, nitrox is super cheap. My LDS charges $10 for air fills and $2 extra for nitrox. It's generally a $10 difference at vacation destinations (Roatan, Cozumel).

Try it out and see if you feel any better after a day of diving nitrox.

 

[rx7diver]

I changed my decompression last stop from 6m/20' to 3m/10'. As I dive in the sea, I rarely deco out as shallow as that...

@Wibble,

When your last stop is at 6m/20', you're breathing 100% O2, correct? What deco gas are you breathing when your last stop is at 3m/10'?

TIA,

rx7diver

 

[Wibble]

@Wibble,

When your last stop is at 6m/20', you're breathing 100% O2, correct? What deco gas are you breathing when your last stop is at 3m/10'?

On open circuit, my final deco gas of choice is 80% (and has been since diving with deco). Not keen on 100% as it's too hot and racks up the CNS at 6m/20'. 80% at 6m/20' will give (1.6 x 0.8 =) PPO2 of 1.28; 80% at 3m/10' will be (1.3 x 0.8 =) PPO2 of 1.04 (but the nitrogen's also lower)

On CCR I try to flush the loop but rarely get much above 1.4 at 6m (off-gassing, don't want to waste loads of O2 with constant flushes).

 

[AfterDark]

That's not correct. You have nitrogen absorption at 1'. There is no deco limit because the amount of excess nitrogen even when fully saturated at those depths isn't enough to cause problematic bubbles when you return to surface pressure.

So above 33FSW a divers body is not off gassing? Why stop at 20FSW for a SS then?