Nitrox Question

[maranda1389]

I just feel really worn out and tired after I dive. I never have headaches or nausea. I just feel physicaly worn out. I don't know if it's because all my gear is so heavy (I'm usually panting by the time I get in the water) or because I breath very very qucikly and deeply due to a little anxiety. Someone said it could be CO2 build up that is making me tired after my dives. I never go past 40' and always do a 3-5 min saftey stop and acend slowly. I also could be a little dehydrated, I drink plenty of water but my doctor still always tells me I am dehydrated.

 

[MaxBottomtime]

Although, Undercurrents magazine reports that the results of a self-directed, anecdotal study indicate that couples who both dive nitrox while on a dive vacation have more sex than couples diving air. Enough reason to use nitrox? Depends on how much you like your wife, I suppose.

I'm sure they meant this nitrox.
Nitrox - www.TheMansChoice.com

 

[Tigerman]

in the water?

Absolutely nothing wrong with sex in the water you know
UNDER water on scuba might cause some issues with the heavy breathing involved of course

As far as the OP, youre both right and youre both wrong.
Nitrox isnt for deep diving, its for extended dive times and SOME (not me) feel better post-dive on nitrox than on air. I dont feel any difference between the two if I dive the same profile on both.
Reason why I always dive nitrox when available is that it drastically cut my nitrogen loading and in effect the time I need for offgasing especially on repetetive days of multiple dives.

 

[k ellis]

if you get a chance to look at a nitrox chart you will notice that the optimal depths are usually in the 60 foot range as this gives the greatest margin of diffrence between air and nitrox. While it does give advantages by extending the amount of time you have to dive by increasing NDLs it does really nothing for dives say 20 feet or so.

I am one who swears by the nitrox being less tiring then air but thats just me and my opinion.

 

[gcbryan]

...

So to settle the discussion between you and your fiance… there isn't much point in using nitrox at very shallow depths since you wouldn't see much of an extension of your NDL - in fact, I believe that the NDL on air at shallow enough depths is essentially infinite (that is, you are offgassing as fast as your are ongassing). As a practical matter, you would run out of air from a single tank even at slightly deeper depths before you would run up against your NDL.
...

Your basic point is correct and if I'm misinterpreting what you've said please correct me but your rate of ongassing and offgassing stays the same (theoretical models) regardless of the depth. It's based on half-lives of the compartments. Some are faster than others but the rate of ongassing is the same as the rate of offgassing for most of the models. What changes by depth is the ppn2 saturation levels of the various (theoretical) compartments.

So, I'm only addressing your statement "(that is, you are offgassing as fast as you are ongassing)".

The NDL at shallow enough depths are essentially infinite which is true but it's because even when saturated at those depths you can always come directly to the surface. You will have more ppn2 in your tissues than you had before you went on the dive but it doesn't matter as your body will always be able to handle that level of oversaturation.

It's not true that for instance by staying at 20 fsw that you are ongassing AND offgassing as your statement would imply. With no change in pressure you are not offgassing obviously.

 

[TSandM]

maranda, from reading your prior posts, I would guess that a lot of your fatigue is stress.

I do know that I was absolutely BEAT getting out of the water when I was diving air. When I switched to diving Nitrox even on shallow dives, I also switched to a different ascent profile, which is slowing my ascent to 10 fpm from half my maximal depth. Whether it's the gas or the ascent profile, I have never had another day of diving where I've dragged my ass out of the water.

 

[Mr Carcharodon]

I just feel really worn out and tired after I dive.

Hi Maranda,

Fatigue maybe the way your body responds to having bubbles in circulation. Of course you can have fatigue just by working hard or by what happened prior to the dive. In any case nitrox will reduce the volume of bubbles in your system. As will keeping shallow and doing slow ascents (which you say you already do). So with the fatigue I would recommend giving nitrox a try.

As far as if it is worth it or not for a given depth take a look at the EAD (equivalent air depth) for different mixes. As a rule of thumb we would say that EAN32 reduces your EAD by 20%, and that EAN36 reduces your EAD by 25%. So for example if you dive EAN32 to 40 feet that is pretty much like doing an air dive to 32 feet. I would not expect much of a difference personally, but listen to what your body is telling you since we are all different.

 

[Crush]

I just feel really worn out and tired after I dive. I never have headaches or nausea. I just feel physicaly worn out. I don't know if it's because all my gear is so heavy (I'm usually panting by the time I get in the water) or because I breath very very qucikly and deeply due to a little anxiety. Someone said it could be CO2 build up that is making me tired after my dives. I never go past 40' and always do a 3-5 min saftey stop and acend slowly. I also could be a little dehydrated, I drink plenty of water but my doctor still always tells me I am dehydrated.

maranda1389,

Heavy exhaustion of your legs just prior to a dive is a great way to predispose yourself to DCI if you believe Doppler studies of microbubble formation (and I do). Dehydration is bad too. Can you make multiple trips to your shore dive site and lessen the burden?

Please take care of yourself and check with a physician who is knowledgeable about dive physiology.

I recently learned about "the second safety stop." It occurs when you just hang out on the surface after a dive and do nothing but float. Tell your fiance that he can swim like a madman if he wants, but you are going to take five minutes to do precisely nothing with zero exertion. It might help.

 

[doctormike]

Your basic point is correct and if I'm misinterpreting what you've said please correct me but your rate of ongassing and offgassing stays the same (theoretical models) regardless of the depth. It's based on half-lives of the compartments. Some are faster than others but the rate of ongassing is the same as the rate of offgassing for most of the models. What changes by depth is the ppn2 saturation levels of the various (theoretical) compartments.

So, I'm only addressing your statement "(that is, you are offgassing as fast as you are ongassing)".

Good point!

Looking back at my words, I see your point, and you are correct, I phrased that in a misleading fashion. Of course, the net flow of nitrogen between tissue and gas has to be in one direction or the other, so you will be net offgassing or net ongassing, depending on where you are in the dive profile. Sorry if it seemed like I was saying that - a better way of phrasing it would be that net gas movement stops when the diver is at a steady state. There is a definable amount of nitrogen dissolved in all tissues at any depth (and even at the surface) once equilibrium has been reached (saturation).

However, if you want to go to the compartment level of this discussion (which is probably beyond the OP's question), then it is still true that you can be simultaneously offgassing and ongassing. I know that there are different models, but if you have a slow compartment and a fast compartment, and then you dive deep and then ascend to a shallower depth, the fast compartment may reach saturation at depth and then begin to offgas in the shallows, while the slow compartment may be nowhere near saturation, so will still continue to ongas even at the shallow depth.

But it is true that the reason why you have infinite NDLs at very shallow depths is that a normal continuous ascent is adequate to eliminate the low N2 levels that represent saturation at these depths.

 

[Crush]

The NDL at shallow enough depths are essentially infinite which is true but it's because even when saturated at those depths you can always come directly to the surface. You will have more ppn2 in your tissues than you had before you went on the dive but it doesn't matter as your body will always be able to handle that level of oversaturation.

I might suggest that gcbryan and doctormike ask maranda about her diving in detail. She claims to dive 30-40 ft with DCI-like symptoms, but perhaps she might occasionally hit 65 ft while spending most of her time at 50 ft? Just an idea...