Nitrox and the Myth of the Longer Dive

[haha49]

In my second open water clas the instrutor let me use one of her metal nitrox tanks and i dove it as regular air and since it was skills it was ok as the prectage was fine and we only did 50 feet on 32 percent.. or something like that.. the amount of time under was about the same as the day befor as the volume of gas was the same i didnt have problems decending as the tank added just enoff weight to help keep me down thats why i was useing it.. i noticed no diffrence what so ever when diveing with nitrox.. for me i dont really see the need for nitrox as my dives are shallow watter dives.. and i never noticed a diffrence..

 

[Twiddles]

 

[RS]

Hey jrock...

Get your nitrox cert. Just be sure to understand what you learn. In this case it's a life saver.

Nitrox is nice for allowing you to have more NDL bottom time, but PPO2, CO2, and N2 are real concerns. You'll get that info in your class and it'll help you on every dive, especially repetitive dives. Then you'll get doubles and will actually have longer bottom times.

 

[miketsp]

I realize the search function does not result in entertaining hyperbole, but just for giggles I did a search in Basic Scuba Discussions for Nitrox Myths. Low and behold, we just had a very similar discussion (Diving using Nitrox?) started Oct 22 and last posted on Oct 27. This was the first result of said search.

I was actually looking for my last post in that thread (#90, Oct 27) after I found a web page called The Truth About Nitrox. This is the only blind study results to my knowledge that adresses the longer dives with Nitrox question with hard data.

Please fell free to impugn this data as you feel neccessary to maintain your hyperbole, but if you actually use the link to go to the web page and actually read the entire report you just might learn something.

There are various studies indicating that the real benefits of Nitrox in terms of breathing rates and work output improvement only appear at high workloads. Here was one blind test done with firefighters:
http://www.usfa.dhs.gov/downloads/pdf/tr_98bw.pdf

The conclusion is that just drifting around a reef or a wreck you won't see a SAC change between air & Nitrox but fighting a current you will.

 

[DIR-Atlanta]

I understand what your getting at about the bottom time and all but what i am not getting is ,are you saying that new divers should not get nitrox certifcations ?

I can't speak for everyone else in this discussion, but my personal feeling is that divers should get Nitrox certified as soon as possible after their initial Openwater checkout. In my opinion, the benefits outweigh the negatives for most divers, so I see no reason not to encourage folks to get Nitrox training right away.

I know that several training agencies are taking the lead on this by allowing divers to combine a Nitrox cert with their initial Openwater cert. I wish more agencies would follow that example.

 

[GDI]

I understand what your getting at about the bottom time and all but what i am not getting is ,are you saying that new divers should not get nitrox certifcations ?if so, why, because it doesnt help them right away thats like saying dont buy a a B/P wing set up because right now you are not going to be diving doubles or you should not get an advanced OW because your not not going down100 ft. I think that the more you learn,the better you are if there are still some people who think nitrox = better sac rate ok so be it.there are many people that do many things and never fully understand what they are doing

Good question:
I'm all for getting the training. But customer service tells me that having a better understanding of the benefits of that training, the best times for the use of the training, the risks and the realities all need to be discussed.

By all means a new diver could benefit from taking a nitrox class or any class for that matter. Go ahead and sell the continuing education modules but provide a better understanding of the benefits and knowledge/expected skills, when and how to use it and when not to. In a lot of my dives I don't bother with nitrox as the application of it is not warranted IMO. Other dives I'm all about it.

Example Nitrox below 40-50 feet on a standard dive is not really required unless you plan on doing multiple dives in high numbers within a short period of time. The Bottom Time and N2 loading vs SAC rate. Yet on deep dives with my SAC rate the appropiate Nitrox % to the depth is used. Using the highest % possible for the dive is not always required. Some dives using 28% vs 36% does not provide a significant amount of advantage in bottom time. 50 % vs 36%, 80% vs 95%. In planning the dive look at exposure times as well as PPO2's, start off-gasing at earlier depth vs longer times at shallow depths. and on and on and on......

It was mentioned here nitrox permits for shorter surface intervals because of N2 loading going into repetitive dives. Ok lets not forget about the O2 clock here as well, usually it has little impact on recreatational dives. Your body only utilizes O2 at a specific rate based on workload. While taking shorter SI may seem as a benefit of nitrox there are other issues that come up and you are not in truth any further away from getting DCI because you are on Nitrox

In taking classes, The benefits don't need to be realized immediately they will come as divers gain more experience, better relaxed and gain better skills. I have seen many divers, who breath nitrox or doing whatever they do and whose diving skills and certifications don't match up, As such in terms of nitrox use they really have not gained anything except a longer potential of exposure time aka NDL which they will never come close to.

 

[PlayaCountryBoy]

All Nitrox does is extend your allowable NDL for the deeper depths. It does NOT change the your repiration rate or tank volume. I have been using Nitrox for 15 years and can tell you...unless your good on your air at around 30 meters (100ft) and would like to stay longer than the 20 minutes allowed...and you could stay longer than 20 minutes, then Nitrox would be a great option for this diver. Or if you're diving on a live-aboard where you're making 4-5 dives a day, in this instance you would definitely feel a difference at the end of the day after diving with Nitrox. Simply, less nitrogen means less fatigue at the end of the day of diving.

 

[D_B]

I don't think I would have liked getting my nitrox cert at the same time as my OW cert, too many things going on with just learning to dive for me to get a handle on it that soon .. I did take more classes right out of OW but having each of them separate enabled me to digest the info easer and kept it fun, not (so) stressful
And as pointed out, not too much need for nitrox untill sac rate improves and/or getting a bigger tank, or doing 4,5,6 dives in a day

 

[Parysa]

This is one main reason why deep, steady breathing is important. You can not always control the level of inspired CO2 (even though it may be small), but CO2 build up WILL have an effect on your breathing. By ensuring to 'vent' as much CO2 as possible, we avoid going into hyperventilation like breathing patterns.

One thing I want to add to this is something I only recently found out. When you are focusing on those deep, steady breaths, make sure you don't breathe too slowly and deeply b/c that can also cause you to hyperventilate. My sister was in the hospital recently having some tests run and she ended up with an abnormal O2 level (I think). The doctor said that b/c she was nervous and trying to relax, she was taking slow, deep breaths and overdid it and made herself hyperventilate. I think the key is just to breathe normally. (I'm not trying to say that that's not what you're saying though, Meng_tze, if that makes sense.)

 

[1_T_Submariner]

Not again!

Poor Horse.