I probably should not say this, bUT...yes, that "line" should not be crossed. However, it is a line with 2 variables, your po2, PLUS the amopunt of time spent at that.

Sooo....in an emergency? A brief minute will not cause the symptoms under most cases, in fact, you will feel less narcosis due to the less nitrogen in the mix (maybe? just a thought).

That being said, I am not recomending thinking of that line as a line to be crossed if you see that big fish just a little deeper, ect. I am saying that the effects are not insantaneous, therefore in an emergency,...well...you get it.

Look at the po2 people are under for controlled amounts of time in medical situations.

 

Here it is in a nut shell. I have been diving nitrox since 92 and wouldn't go back, however I never dive in water deeper than 130'. If you are planning a dive in deeper water then just don't take nitrox with you. It is that simple. I absolutely feel 100% better after a dive with nitrox than with air, so for me the benefits far outweigh the negatives. In the mid to late 90's my buddy and I were diving 3 tanks a day 3 or 4 times a week. It to me is safer if you follow the guidelines. I also say if you are hanging in waterdeeper than 190' and suspended and shoot a cobia period you have rocks in your head. I have shot many cobia and have yet to put a kill shot on one. So that to me is suicide reguardless of the gas you are breathing.

 

I'm with the previous poster, and I don't dive on "air" at all. Yes, there are some Nitrox specific risks, but there are just as many, or more, with breathing air, heli-ox, tri mix, etc....

I like it mainly for two factors; I feel better after a day of diving and I like the additional safety barrier against DCS (bends).

Yes, you do have to be more mindful of your PO2, but if you observe the recreational limit of 130', you will not exceed the prevailing limits. Oxygen toxicity is also a cumulative issue, not a solid wall, meaning you will not necessarily have any problems if you exceed your PO2 level for a short time, but if you continue to load high oxygen levels, you may experience those nasty neurological symptoms.

Safe SCUBA is all about knowing your abilities and limits, and staying within both.

I recommend doing as much research as you can on the subject before making your decision.

 

Another issue I haven't gotten a clear picture of is the use of steel over aluminum tanks. Is there a reason the majority of Nitrox divers use steel, other than the higher volume and pressures they give?

 

The amount of benifits that you obtain by diving nitrox far outweighs the few limitations that it puts on you as far as depth. As with anything in diving, there are limitations.

If the sand is shallower than your maximum depth on nitrox and you follow all other guidlines, I see no reason to worry about air vs. nitrox. I feel so much better when I dive nitrox. Before I got my nitrox cert, I was getting sick:sick fairly often after about the second dive of the day on almost all trips. I have yet to get sick since diving nitrox.

Turtlebait (12/28/2008) Another issue I haven't gotten a clear picture of is the use of steel over aluminum tanks. Is there a reason the majority of Nitrox divers use steel, other than the higher volume and pressures they give?

Steel gives you more air as you said and allows you to drop weightdue to the buoyancy characteristics. Aluminum tanks become positive towards the end of your dive requiring you to carry more weight to begin with.

 

Nitrox is the way to go. do youre homework and you will find this to be true. most people dont have to worry about taking an o2 hit if they follow the parameters. i myself try to keep my po2 below a 1.6 but have often gone to 1.8. not recommending this just FYI.

as far as the steel vs the al. Steel is the way to go. you get to drop weight off of youre

belt and if you ever ask a commercial spearfisherman,the will only recommend steel. since those guys probably dive more than anyone else. i will take there opin.

SSI

 

well i guess i'll give my $.02 since i was mentioned at the beginning of this post.

you guys/gals can keep arguing the pros/cons of nitrox vs air till the cows come home,

AIR IS NITROX

21% to be exact

all you are arguing is the safety factor and pushing the pp02 limits. one of the first thing you learn in training (or should be depending on who's teaching) is that you plan you mix based on you planned depth. now, as you advance in training and start to dumb things like touch the sand...you plan your mix for the max you could hit in a given situation...which at the "O" is a different situation because then everyone would be diving air.

anyhow, back to the point, when spearfishing something like the tennaco rig, most people will take a mix for 170' because likely they will not go to the bottom and dig a 10' hole and sit in it for an hour.

now draw your own preferences as to richer mixes, yes it makes you feel better after diving, yes it doesn't give the dry mouth, and yes if done properly IT IS SAFER

cheers

 

IMHO the two things any diver can do to make diving more enjoyable is A: Buy a computer and B: Get NITROX certified.

 

After reading your comments and talking with a Nitrox instructor today, I signed myself up for the Jan 7 Nitrox class.

The main selling point was about feeling better after a dive - no headaces, no nausea,etc. I don't think I'll be getting a Nitrox computer just yet. I'll keep my air computer for a while, get used to the whole Nitrox scenario, then look for a computer that reflects my dive parameters.

Thanks to all who posted on this subject:clap I applaud your knowledge and understanding to a diver who was overwhelmed by the whole thing.

Again, my humble thanks:bowdown - Ric

 

I like the shorter SI.

 

Turtlebait (12/28/2008)

Nitrox, with its higher O2 content, "draws" a line in the water column which youMUST NOT pass under penalty of Hypoxia, which could lead to convulsions and/or DEATH! That's a hell of a penalty to pay if for instance a cobia or amberjack drags you past your planned depth.

According to NAUI, the safe ppo should not be greater than 1.4ata. But of course with all the different physiologies and environmental concerns the individual diver brings into the equation, you may still experience hypoxia.

First of all, you are confusinghypoxia (0.6 ATA or less) with CNS O2 Toxicity (greater than 1.6ATA), also known as the Paul Bert Effect. Also, the maximum exposure for recreational dives is 1.6 ATA while the U.S. Navy Exceptional Exposure Working Limit is 2.0 ATA. I plan all my dives with a 1.6 ATA (no decompression). If you plan decompression with EANx mixtures with high oxygen content, then your maximum bottom mix oxygen partial pressure should not exceed a maximum of 1.5 ATA. If heavy exertion and/or thermal stress is going to be encountered in the dive profile, the maximum bottom mix oxygen partial pressure should be limited to 1.4ATA. For no decompression dive profiles, 1.6 ATA is perfectly safe. Just remember that at 1.6 ATA, you should limit a single exposure to 45 minutes with a 24 hour maximum of 150 minutes. With Nitrox I (32% O2) you are limited to 132 feet. That doesn't mean that at 135 feet you are going into convulsion. When diving Nitrox, plan your mix to reflect the deepest depth you could reach on a particular dive. For example, if you are diving a sitewhere themaximum depthis 160', fill your tank with 27% O2. In that way, you'll be safe if you get dragged to the bottom by that big one. You could do like I do, keep air in your pony and switch to the pony if you exceed your maximum Nitrox depth. Bottom line - go Nitrox and you'll never dive air again.

 

Yurtlebait...I have an air only computer also, and I still follow its profile when diving, even though I always dive ntirox. That provides a HUGE margin of safety for me. I get the benefits of nitrox as far as felling better, and especially having less nitrogen loading in my system if shit ever does hit the fan, and I have to make an emergency accent, ect...but I am missing out on the longer bottom times and shorter surface intervals without a nitrox computer.

I will be getting one soon, but for about a year and a half I have been diving that way, and it is perfectly fine, and in fact much safer.

 

Just out of curiosity, what's your preferred mix? - Ric

 

For 99% of the diving I do around here, 32% Nitrox works well for me. If I know I'll be staying shallow (less than 80'), I'll occasionally get a 36% mix.

 

Most popular mixes wefill at MBT are 32% and 28% - with the occasional 26% for Sean.

 

I dive nitrox every chance I get and like Clay I use my computer on air for the extra safty margin. Lord knows we all need murphy repelant! I also never get headachs after a dive now. Always plan your dive and dive your plan.

 

Go with nitrox, steel tanks, and a good computer. Your main consideration when it comes down to it, is your safe diving plan. DCS and other things can happen to the best trained divers doing everything right. Rely on your training and dive smart, you will enjoy the benefits of nitrox and steel!

 

Sniper Spear-It (12/28/2008)most people dont have to worry about taking an o2 hit if they follow the parameters.

Very true. However individual variation is also something to consider in case you are not like "most people." I get nauseous at 1.4 at REST and at 1.2 while working. Who knows what would happen to me if I am working at 1.6. One thing is for sure, I'm glad I already know I am o2 sensitive and am not gonna find out the hard way. Do any of you know your personal o2 limits?



Keep in mind there are many things that can make you more susceptible to ox tox such as work load- some people have CONVULSED as low as 1.6 po2 while they are working hard. Skip breathing, co2 retention, stress, aspirin, amphetamines and other stimulates also increases the risk of ox tox.

 

During Nitrox class on Jan 7, we touched on how our different physiologies will produce different reactions to the same diving scenarios. All we concluded was to not push the limits till we each found our "comfort zones". Just how did you determine you O2 sensitivity? - Ric

 

I, for one, have not found my level of "oxygen sensitivity" as of yet. This may be because I tend to dive very conservative profiles, and rarely breath over a 32% mix. I also tend to limit myself to no more than 2 dives per 24 hour period, and try not to get into any reverse profiles.

On the same note, I have yet to find my nitrogen sensitivity limit, as I have never been "narked" to my knowledge.

 

SCUBA Junkie (1/8/2009)

On the same note, I have yet to find my nitrogen sensitivity limit, as I have never been "narked" to my knowledge.

The BEAUTY of being NARCED, is you DON'T know you're NARCED, until someone ELSE tells you how GOOFY:letsdrink you were acting! - Ric

 

Turtlebait (1/8/2009)

SCUBA Junkie (1/8/2009)

On the same note, I have yet to find my nitrogen sensitivity limit, as I have never been "narked" to my knowledge.

The BEAUTY of being NARCED, is you DON'T know you're NARCED, until someone ELSE tells you how GOOFY:letsdrink you were acting! - Ric

If you do not know that you are narced then you are way beyond where you need to be. Kind of like the whole drinking thing. I know when I am drunk/buzzed. You can feel it coming on. I have felt being narced a few times. I have always felt it and new I was narced. I don't get goofy when I get narced. I get more aware that something is not right and that I need to concentrate on correcting the situation. I usually know I am narced when I turn my head and my head starts spinning. Kind of like that feeling you get when you're drunk and you close your eyes. I know that's my cue to accend a bit.

 

Turtlebait (1/8/2009) During Nitrox class on Jan 7, we touched on how our different physiologies will produce different reactions to the same diving scenarios. All we concluded was to not push the limits till we each found our "comfort zones". Just how did you determine you O2 sensitivity? - Ric

I recently discovered that I got this very "deep" feeling of nausea whenever I deco'd on o2, even on different o2 bottles. It got better on air breaks and completely away after I got off the o2 for a few minutes. I felt it at 13 ft.



A few weekends ago I did something stupid and did a dive that was a lot more work then I anticipated on a mix that made a po2 of 1.2. That very same nausea came back although not quite as intense. To give you an idea how hard I was working, I swam my butt off 34 minutes against the flow, then turned around and drifted back in 14 minutes not kicking once. I knew better but for whatever reason I did the dive so now I know if I'm working pretty hard, 1.2 is too much. Sounds kind of ridiculous but its a very distinct feeling.



100% o2 at 13 ft is 1.4 and I got the nausea at complete REST on the 02. I was taught to decrease the po2 by .2 when planning a working dive so it seems completely reasonable that I could get the nausea at 1.2 on a working dive.



My point of bringing it up was to remind us all not to assume that we're good on a working dive at 1.6 even though we are taught that we SHOULD be ok at 1.6. Heck I'm not even good to go at 1.2. Let's say I am doing a nice easy dive at 1.6 and maybe my stomach feels a little funny but I think it may be from those tacos I had for lunch or the rough ride out to the dive site. If something bad happens and I've all of a sudden got to work REALLY hard to save my life I my ox tox problems may certainly increase. However in this case I don't have the option of halting my dive, grabbing onto a rock and resting till I slow my breathing and get rid of some co2 because this situation that is making me work hard is life threatening. I'm screwed.

 

Love Nitrox, am a huge proponent for getting Nitrox certified. As with Air or any type of mix you use plan your dive and dive your plan.

I take into account how deep I might possibly go too for an optimal but safe mix....



I used to dive with my computer on air a lot but it depends where I am diving and what my mix is too.



If I dive the "O" I try to keep it real and dive with my computer on my mix due to the depth of the wreck vs the bottom depth.



Jim we seem to hit a lot of 30 and 32 mixes and some 28's too but you guys are doing a lot more "O" divers than we do in a year...