Nitrox Question

[DandyDon]

Here's another: If you dive Nitrox on the deeper dives, then you'll be more likely to qualify as a Buddy for the more experienced divers. If you're on air, I know I wouldn't want to Bud with you, as you'll need to ascend well before I will.

If you dive on air tables (or computers), it decreases the risk of decompression sickness...

I hear this one, but it just strikes me as silly. The chances of DCS are so small anyway, that this is actually not a real reason.

 

[DepartureDiver]

Here's another: If you dive Nitrox on the deeper dives, then you'll be more likely to qualify as a Buddy for the more experienced divers. If you're on air, I know I wouldn't want to Bud with you, as you'll need to ascend well before I will.

good point ... and the verdict is nitrox is worth it.

The chances of DCS are so small anyway, that this is actually not a real reason.

But I have to disagree here ... if you get a hit you'll wish you did something to give yourself some more padding ... and any decrease in N2, even 10% can be significant ... but of course it is hoped that divers don't push the limits and do things smart ... which does make the risk smaller. However, it can't be forgotten there is a real (but small) statistical risk of getting a hit after 40 minutes at 60'

 

[-hh]

So, I'll throw it out here; do you think diving Nitrox is "better"?

IMO, it really depends on your SAC. If you still have the high air consumption of a Novice, you're supply-limited as opposed to DCS-limited, so the benefit of Nitrox is pragmatically zero.

If your SAC is good enough, and your dive depths are in NItrox's sweet spot, then it can be worthwhile.

You'll probably get a wide variety of responses on how much Nitrox training is worth, but IMO, anything over $75 is not a good value (you can add a little more to this if it includes supervised dives). I'm personally astounded at the rips I've seen at some resorts...for example, how good does $299 for Nitrox certification, and then $12/tank sound?


-hh

 

[IndigoBlue]

Nitrox is better for:

1) dives between 50 and 100 ft

2) repetitive dives deeper than 20 ft

3) longer bottom times for photography or hunting, but then you also need bigger tanks as well

 

[DA Aquamaster]

Now just think of the next fun step ... getting a small sling tank filled with more oxygen so you can off-gass much faster at safety stops ... and then you'll really have been bitten by the bug to be safer and maybe start transitioning into technical diving.

An oddity I have noted on deeper dives (130'-140') on a cooler nitrox blend (26%) is that the deco is about the same for a 20 minute bottom time using 26% for both the bottom mix and deco as it is for the same dive using 21% for the bottom mix and 50% for the deco gas but you use a whole lot less O2 on the air/Nitrox 50 combination.

In general if I only have one deco gas along, I prefer Nitrox 50 over 100% O2 especially given the current trends in gradient and RGBM models and the deeper stops that result.

Nitrox does impose solid depth limits so you either need to plan your dives well in advance or buy more tanks to keep more nitrox mixes on hand and on the boat.

And I agree with the comments that it is largely a waste of money if your sac rate is excessive.

Many people indicate they feel better diving nitrox and I agree this is ture in many case. But I also think much of that benefit can be obtained on air using a slow and stepped ascent if diving a wall or with some deep stops on ascent if diving on a relativley level dive site.

Or again, much like in the original example, the feel good benefit of Nitrox can be relaized on no deco air dives by using a relatively hot deco mix like Nitrox 50, Nitrox 80 or even 100% O2 during the normal recreational saftey stop.

So don't stop with Nitrox certification but go ahead and get an Advanced Nitrox certification and buy yourself a 30 or 40 cu ft deco bottle.

 

[Michael Schlink]

Nitrox absolutely but I disagree with some of what has been said.
There is not any reason to dive Nitrox and use an air table, although some will say that diving Nitrox is more safe as regards DCS/DCI there is little to no statistical evidence that diving Nitrox is safer. It does make sense that less nitrogen loading would decrease your chances of a hit but as the "odds" of a DCS hit are extremely low as it is the increase in safety margin is very small.
The #1 reason to dive Nitrox is increased bottm time on a square profile dive between 60 and 130 FSW.
The other added benefits are;
Shorter surface intervals
Decreased gas consumption-a study was done and showed about a 12-13% "decrease" but this can be argued pretty hard
Less fatigue after diving- many people, including my wife, claim that they do not feel the post dive fatigue, especially after several days of repetitive diving
If you are diving tables you'll see a dramatic increase in available bottom time, toss in a Nitrox capable computer and bottom time takes a back seat to air supply.
There is really no "down side" to diving Nitrox as has been mentioned.
The particular "mix" will have a specific depth that you cannot descend past without serious consequences, however dive planning and normal safety concerns should be in place already and you shouldn't be diving past these depths in normal recreational depths example 32% can be dived to 130fsw and 36% you must stay above 100fsw
Now dive a 36% mix between 60 and 80ft and watch the increase in Bottom time
You will need to track your 02 "clock" but that's easy and typical normal diving won't get you near an 02 exposure problem
I taught 3 guys Nitrox on a liveaboard in Indo. in Dec. At first they weren't all that interested, until they compared their air computers to the Nitrox computers-Now they're hooked
I think that one of these days you'll see Nitrox is the norm and air will be the "old way" Example; a dive resort thatwe go to fill more Nitrox tanks per day than air
As far as cost goes it is a little more expensive but if you factor in the increase in bottom time and run a cost per minute of diving it might actually be cheaper than a tank of air-Go for it

 

[DepartureDiver]

An oddity I have noted on deeper dives (130'-140') on a cooler nitrox blend (26%) is that the deco is about the same for a 20 minute bottom time using 26% for both the bottom mix and deco as it is for the same dive using 21% for the bottom mix and 50% for the deco gas but you use a whole lot less O2 on the air/Nitrox 50 combination.

Interesting. I don't find this. As an example (done with mine on an acceptable profile), for 140' for 20 minutes I get a deco of 20 min with the 26% alone with the first stop at 60'. But on air and a 50% deco gas, the deco time is reduced by 25% to 15 minutes, plus the first stop is now deeper (which would be expected) at 70'.

 

[DA Aquamaster]

I get differences of 1 to 4 minutes depending on the program I use. I tend to use Palm based applications as I don't worry about an $80 PDA on the boat nearly as much as a laptop.

I have been using DPlan but also recently started playing with Palm VPM which seems to be consistently more conservative.

Using DPlan with 140' for 20 min with air on the bottom and 50% for deco I get 19 minutes of deco with deco starting at 90 feet and the first stop at 60 ft.

Again with DPlan but with 26% used for both bottom and deco gases I get 22 minutes of deco with the deco starting at 80 feet and the first stop 60 feet.

With Palm VPM (conservatism set at 2) with air on the bottom and 50% for deco, I get 20 minutes of deco with the deco starting at 97 feet and the first stop at 70 feet.

With Palm VPM with 26% for both backgas and deco, I get 24 minutes of deco with the deco starting at 89 feet and the first stop at 60 feet.

Of course that is with the dives occurring at 5000'

At sea level the deco drops to 16 minutes on air/50% and 17 minutes on 26% with DPlan. And decreases to 18 minutes on air/50% and 22 minutes on 26% with Palm VPM.

I guess I should amend my statement to say that with DPlan, I see very little difference in deco between air and 50% versus 26% Nitrox for the entire dive. (ie. 1 minute difference)

But the original point is even more clear in your example as air and accellerated deco on Nitrox 50 gets you out of the water faster than doing the whole dive on 26% Nitrox.

 

[Ryukyu-diver]

Or buy yourself a transfill whip or a booster have your tanks O2 cleaned, put the required amount of pure O2 in your tank at home in the garage, then go to the shop and have them top with air.

There is a vast amount of good solid advice and points made concering Nitrox on the thread but, for your own safety don't even begin to try this until you have had a lot of training as well as proper equipment.

 

[pbr]

There is a vast amount of good solid advice and points made concering Nitrox on the thread but, for your own safety don't even begin to try this until you have had a lot of training as well as proper equipment.

Thanks everyone for all the info. The consensus seems to be "go for it", so I will!

I saw a lot of remarks on tables but I have the UWATEK SmartCom which is Nitrox compatible. Also, I'm not planning on doing much diving below 100 feet anyway...

Lastly, I didn't see any remarks about needing equipment to "verify" the O2 mix. Are these mandatory; expensive??