Safety stop on Oxygen or Nitrox

[String]

Advanced Nitrox for me isn't really a "tech" course. Its the first part of the severe dive skills and competency workout you need before starting tech training. From that, id say its very useful even for someone who has no interest in technical diving as it WILL massively improve their comfort level and skills regardless of their entry level.

 

[Rhone Man]

It's all about risk-benefit. If you dive comfortably within the limits of whatever decompression model you are using, your DCS risk is extremely low (even as we age!).

Yes and no. When I was in Truk, we were all doing 4+ dives a day below 100 feet, and although we were all staying within the NDLs on the computers, toward the end of the week people were experiencing minor joint pains in the evenings which had disappeared by the following morning. Maybe nothing to do with DCS, but I have my suspicions. The models just get shakier and shakier the more heavy repetitive diving you do (which we all knew anyway, right?).

It crossed my mind more than once that carrying a bottle of 80% for the safety stops (had it not been so exhorbitant in that part of the world) might have been a very prudent precaution.

Just for the record, we were doing 6 minute safety stops after each dive.

 

[ramasule]

I am positive that an Advanced Nitrox course would be an easy transition for him... and would answer many of his questions



I don't see the need to do this at the safety stop. For a no-deco dive, the benefit is so intangible that O2 might as well just be breathed on the boat.

When I lived in the UK, I had an O2 cylinder that was often used as a
'pick me up'. The best hangover cure I ever used was 1hr of O2, along with 2 bottles of Lucozade Hydroactive and a McDonald's breakfast...

I second this. My buddies and wife are lifeguards at a pool. There has been a couple times after some very heavy drinking that I have ended up there sucking back some O2 with mcdonalds and poweraid. I can confirm the above statement by Devon as 100% true

 

[rjack321]

Yes and no. When I was in Truk, we were all doing 4+ dives a day below 100 feet, and although we were all staying within the NDLs on the computers, toward the end of the week people were experiencing minor joint pains in the evenings which had disappeared by the following morning. Maybe nothing to do with DCS, but I have my suspicions. The models just get shakier and shakier the more heavy repetitive diving you do (which we all knew anyway, right?).

It crossed my mind more than once that carrying a bottle of 80% for the safety stops (had it not been so exhorbitant in that part of the world) might have been a very prudent precaution.

Just for the record, we were doing 6 minute safety stops after each dive.

Ok I get there are no boosters in Truk.

But if you were just going to do 6mins on a different gas... why on earth would you use 80%? 2000psi of O2 even in a cylinder as small as an al19 is enough for 6mins at 20ft. In an al40 2000psi of O2 is good for ~30mins at 20ft.

And since you were diving air/nitrox and nitrogen is the only inert you need to eliminate, having 20% less of it is significant.

 

[DevonDiver]

But if you were just going to do 6mins on a different gas... why on earth would you use 80%? 2000psi of O2 even in a cylinder as small as an al19 is enough for 6mins at 20ft. In an al40 2000psi of O2 is good for ~30mins at 20ft.

OMG.... did you just make a case for............a Spare Air cylinder!! :shocked2::shocked2::shocked2:

 

[rjack321]

OMG.... did you just make a case for............a Spare Air cylinder!! :shocked2::shocked2::shocked2:

Nitrox spare air :cool2:

 

[DevonDiver]

You know they actually sell that, right? sigh

I was thinking of one for 80%... complete with MOD decal. That'd turn some heads on the dive boat...

 

[Rhone Man]

But if you were just going to do 6mins on a different gas... why on earth would you use 80%? 2000psi of O2 even in a cylinder as small as an al19 is enough for 6mins at 20ft. In an al40 2000psi of O2 is good for ~30mins at 20ft.

And since you were diving air/nitrox and nitrogen is the only inert you need to eliminate, having 20% less of it is significant.

You could use pure O2; I just threw 80% out there because out of habit I don't like to go richer than that.

I did find it interesting though: after each dive I made it a habit to check my "no-fly" time on my Suunto, and normally it would be around 25 hours, except for after the one planned decompression dive I did, where after spending a chunk of time plus extended safety stop on a fairly rich mix, I came out with a calculated "no fly" time of a meagre 15 hours.

 

[rjack321]

You could use pure O2; I just threw 80% out there because out of habit I don't like to go richer than that.

Because? You were trained in the differences between 80% and 100% no?

I did find it interesting though: after each dive I made it a habit to check my "no-fly" time on my Suunto, and normally it would be around 25 hours, except for after the one planned decompression dive I did, where after spending a chunk of time plus extended safety stop on a fairly rich mix, I came out with a calculated "no fly" time of a meagre 15 hours.

That's because repetitive NDL diving (esp. with the relative rapid ascents recreational divers typically do) is frequently more aggressive than planned decompression dives. At least mathematically.

 

[String]

Multiple dives over a short period of time combined with short surface intervals are still where most tables and deco models struggle.