Diving using Nitrox?

[Thalassamania]

Diving appropriate EAN-X on Air tables is always a good idea.

 

[Meng_Tze]

I see two intertwined threads here:

One that covers the benefits of Nitrox (narcosis, SI, etc) and another one that covers gas management (rock bottom, time to ascend etc).

While related at the dive planning level, for the purposes of clarity should we keep them separate?

 

[Leejnd]

I see two intertwined threads here:

One that covers the benefits of Nitrox (narcosis, SI, etc) and another one that covers gas management (rock bottom, time to ascend etc).

While related at the dive planning level, for the purposes of clarity should we keep them separate?

Seems to me the topic of gas management only came up as it pertains to whether or not a recreational diver would ever find themselves ending their dive due to NDL's vs gas supply. So in that context I believe it's applicable.

I believe the point was supposed to be that, following the specified formula, no one would ever be able to dive more than 35 min. at 70 fsw -- the point being that, given that formula, recreational divers who properly manage their gas supply would rarely if ever find themselves in a situation in which Nitrox would be of benefit.

Again, I disagree. Not being very good at math myself, i'm not even going to TRY to figure that formula out. I use a computer. And I can say unequivicably that I have ended dives on air due to NDL times, with plenty of gas supply left, and hence would have benefited from Nitrox.

 

[boulderjohn]

I believe the point was supposed to be that, following the specified formula, no one would ever be able to dive more than 35 min. at 70 fsw -- the point being that, given that formula, recreational divers who properly manage their gas supply would rarely if ever find themselves in a situation in which Nitrox would be of benefit.

I believe that with tha formula, we are seeing an over-application of the Rock Bottom concept. Carried to an extreme, Rock Bottom would have us end a recreational dive with probably half the gas left in your tank, assuming a decent SAC rate. The idea is that we should always have enough gas to contend with the remotest possibility of equipment failure and OOA for both ourself and our buddy. For me, this makes loads of sense in many situations (as in cave diving), but it is going way too far for a relatively shallow recreational dive with no required safety stop.

One can argue that we can never be too safe. That argument would have us drive across the Utah Salt Flats on the Interstate highway at 10 mph. At some point you need to say that you are willing to accept a little more risk. Personally, I am willing to extend my bottom time on a 70 foot dive past 35 minutes. Call me crazy, but I have done it often.

 

[BTravlin]

This thread has been rather confusing for one who is a relatively new diver and not Nitrox certified.

I have recently been reading up on Nitrox since my wife and I are planning on doing a liveaboard in the Turks & Caicos this summer. It looks as if the dive profiles there plus the repetitive diving over the course of a week would make Nitrox certification a good idea for this trip. Comments?

 

[Meng_Tze]

I believe that with tha formula, we are seeing an over-application of the Rock Bottom concept.

Over application? How about incorrect application?.........step 1 allows for 2 divers, step 9 adds 200psi reserve and after that another 200psi? So gas allowance is for 2 divers, plus 400 psi..... 400 psi at what breathing rate though, there is no allowance for that at the later stages. The idea is there in the overall plan, the execution seems to lack flow and too conservative.

My two cents after re-reading the posts. Or maybe I just don't understand.

 

[Thalassamania]

My two cents after re-reading the posts. Or maybe I just don't understand.

I'm with you Comrade Diver.

 

[Rainer]

The idea is that we should always have enough gas to contend with the remotest possibility of equipment failure and OOA for both ourself and our buddy.

Do you understand Rock Bottom? I mean at all? The majority of gas that I reserve is for dealing with a problem at depth, plus ascent, not my shallow stops. And RB doesn't really help if both divers are OOG...

 

[billeelou]

I am 275 lbs on a good day and my limited dive experience even I can get 50 minutes on a AL80 @ EAN 21 at 50-60 feet every day on a non-stressful dive( no fighting currents, etc.) but since >49 dives qualifies as an expert in the use or non-use of Nitrox, I will put in my two cents.

When I dive with Nitrox, I feel better later in the day and later the next day. If it is placebo effect, so be it, thats worth the extra $6-9 a tank. My NDL is extended or I can follow the ECO drive's dive reccomendation on air for an additional margin of safety, Cause Funny as it may seem, no DCS is worth that extra $6 to me.

So is it worth the course, naw? Pick up the NOAA materials( as they were one of the first ones to develop the nitrox tables) study hard, get an analyzer and stay well within the guidelines, and then it is worth it!!!

 

[boulderjohn]

Do you understand Rock Bottom? I mean at all? The majority of gas that I reserve is for dealing with a problem at depth, plus ascent, not my shallow stops. And RB doesn't really help if both divers are OOG...

Perhaps I misread what the poster wrote, and perhaps I am talking about a misapplication. And finaly, perhaps what I wrote was not what I intended to write. All are possible given the fact that I am darting in and out of this thread whilst attempting to get some work done. I should have been more careful. In this case, what I read was that the poster was trying to apply RB principles to say that no one could do more than 35 minutes on a 70 foot dive, and I was disagreeing with that applicatiion.