nitrox advantage?

[jon m]

hey all-
considering taking nitrox cert but i got to thinking...
in my (limited) experience with multiple dives, i either ran out of air(hp100) or ran out of dive time on my comp (scuba pro smart com). i thought the (main) advantage of nitrox was longer bottom time. how does this work? last time i dove it was about
(without log in front of me) 75' for 45min (used all air, 500psi left) then 57' for 46min (no bottom time remaining on comp , about 900 psi left) then 36' for 42 min (cold,cold,cold! about1100 psi left). i'm sure my air comsumption went up on second and third dives as i got colder... all of my "home" dives are cold water,(so 2 dives per trip will be likely, 3 is COLD!) am i only going to see an advantage on my second dive? what are your thoughts, and why do you use nitrox?
thanks!

 

[H2Andy]

yes, the same two dives carried out in air will give you shorter NDL times than if you did them using Nitrox

Nitrox will make your dives "shallower" in terms of Nitrogen absorbed into your system, and thus will give you longer dives than the same dives with the same surface interval done on air

how much "longer" will depend on a few things. for example, Nitrox is best between 70 and 90 feet or so ...

also, your air consumption doesn't change with Nitrox, so if you run out of air before you run out of dive time, Nitrox won't help much

i use Nitrox mostly to avoid deco time on dives. i can stay down longer without having to worry about doing deco

 

[Fordan]

Nitrox's primary benefit is lowering the amount of N₂ you take on for a given depth compared to air. This can mean longer bottom times if your bottom time is being limited by NDL. It can also mean it's an extra safety margin if you follow air tables (or if your dive is air-time limited). There's also anecdotal evidence of it giving you more energy/making you feel less tired at the end of a dive.

The tradeoff is the extra complexity of dealing with the Nitrox (keeping O₂ clean tanks, testing the mix, etc) and dealing with the additional O₂ exposure, meaning depth limitations and keeping track of your O₂ levels similar to how you do your N₂ levels (although a lot less likely to end a dive)

 

[ClayJar]

...am i only going to see an advantage on my second dive?

Yes... for now.

I picked up my nitrox card at the very beginning of my diving. (I went to the shop before my checkout, and they told me I could come that evening to pick up the nitrox class if I wanted, so I did.) Anyway, at that point, I was always air consumption limited on my first dive, but on the second dive, the residual nitrogen loading from the first dive was such that I would hit the NDLs before I reached ascent pressure. By diving nitrox, I could stay on the bottom (where the interesting stuff is) longer before starting my ascent.

(The irony, of course, is that by using nitrox to extend your NDLs to allow you to stay on the bottom longer, you actually go through your gas faster. I like to tell new divers that nitrox will help make their dives shorter, but more interesting. It makes them think. )

Anyway, where I am in my diving now, my air consumption is low enough that I can toss a tank on my back and head down to 85' in a quarry and play around until I'm nearing my NDLs on air on the first dive. Diving nitrox now can extend my time on the bottom, even on the first dive.

 

[Humble older aquaman]

Fordan observations, mostly agree. Another benefit will be if you travel to a warm destination. Many more resorts and live aboards offer/rpomote Nitrox because in warm waters of 60 to 100 feet, depth of huge variety of wrecks and reefs, your bottom time can be expanded safely. Factor in the multiple days of multi dives each day, and Nitrox evn becomes more attractive, if used within comfort zone and tables.

Another intangible benefit is learning more about enriched air, air consumption, pro's/cons etc...understanding what makes us humans tick underwater ought to be an ongoing education for all of us!

Hope you take the plunge into the Nitrox world and enjoy it, Good Luck!

Hoa!

 

[Buoyant1]

NDL's are the huge consideration! I didn't think it would matter much, but after comparing a good bunch of dives I did last summer on Nitrox to the air tables, I would have been over on several occasions!

Anyway...I just think it tastes better .....(kidding)

 

[Thalassamania]

I dive nitrox almost all the time, but usually on air tables, my spinal cord has been good to me so I try to be good to it.

 

[Fotoz4FX]

The last time I dove was with Nitrox. Granted my air consumption on a regular basis is pretty remarkable for my age (56) but I got 156 minutes on a single 80 with just 32%. Notable was the fact that I only went to about 26 feet diving for fossils but I think my air consumption might have been noticeably less had I done the same dive on air.

 

[renpirate]

As others have stated often, Nitrox offers advantages in longer bottom times. However, it also offers shorter surface intervals as well. Many people dive Nitrox on a regular basis and report feeling less tired after diving. Although, I have found this to be similarly reported by everyone I have discussed the topic with, the scientific studies are still inconclusive on this topic.

Ultimately, you should decide for yourself. I do advise taking the class since it is fairly cheap and it gives you additional options, not to mention extra emphasis on dive physics and physiology.

 

[Dive1Dennis]

Jon,
I think that the Nitrox course is a good value and have no regrets about taking it. Most of my diving at home is of the deeper variety where nitrox does not provide a significant advantage. But I did a week long trip to the Cayman Islands a couple weeks ago. I dove EAN32% for the entire trip.

My Suunto computer is an air only type, and I also wore a borrowed nitrox Suunto computer so I was able to compare the two. We dove three or four times a day, max. depth of around 95 to 110 ft. (MOD for the 32%) early in the first dive, and typically shallower dives after that.
While I never pushed my air computer into any deco obligations, my dives did typically pushed the limits of my air computer. I had several dives that were down to a couple minutes of no-deco time on the air computer. The Nitrox computer always gave me significantly more no deco time. I could have done all the same dives on air and I would have been fine. Even though I did not use the additional bottom time that the nitrox allowed, I still perceived two advantages;
1) An additional margin of safety. I was especially happy about that considering that I was doing multiple dives per day over the course of five days.
2) I felt decidedly better, less fatigued after the day of diving. I know there are no hard facts about this, but I believe it makes a difference.

Go ahead and take the course, you will learn a lot and it will give you some additional diving options.