Nitrox

swimmer_spe · Jul 13, 2014

I am planning within the next year to do a live aboard in AUS for a few days to dive the GBR. For anyone that did it, how many dives would be done in a day?

Would being on Nitrox be a way to avoid hitting my NDL too quick? Other options?

00wabbit · Jul 13, 2014

Yes, Nitrox would be good to reduce the nitrogen intake over multiple dives over many days. Especially if there are deeper depths or longer dives.

BRT · Jul 14, 2014

I wouldn't say nitrox is a big advantage with deeper dives. It's most effective down to around 100 feet. Below that you rapidly need to lower the O2 concentration to avoid toxicity.

swimmer_spe · Jul 14, 2014

So, If I plan between 60-80 feet, I can hypothetically last longer on Nitrox?

Storker · Jul 14, 2014

swimmer_spe:
So, If I plan between 60-80 feet, I can hypothetically last longer on Nitrox?

For some dives, yes, for other dives, no. It depends on your depth profile, tank size and SAC rating. On a small-capacity tank like an Al80, you can easily run out of gas before you reach your NDL time, even on air. Particularly if you dive a multilevel profile.

You get more benefit from nitrox if you do multiple dives per day with short surface intervals, since the lower nitrogen loading translates to longer bottom times for the second, third and perhaps fourth dive.

MXGratefulDiver · Jul 14, 2014

Liveaboards typically will offer 4 - 5 dives per day. If it's your intention to do every dive available, then nitrox is best suited for that type of diving.

... Bob (Grateful Diver)

KeithG · Jul 14, 2014

swimmer_spe:
Would being on Nitrox be a way to avoid hitting my NDL too quick? Other options?

Nitrox is commonly used on live aboards to extend bottom time. Other potential options are
- to not dive so deep
- perform multi level profiles instead of square profiles
- skipping a dive to off gas

Oldbear · Jul 14, 2014

The benefit of using Nitrox is that it exposes you to less nitrogen than dive with "air". This provides some advantages:

It extends your allowed bottom time.
It reduces any need to "push" or get near the air no decompression limits.
It reduces your overall nitrogen load on multiple dives.

I personally find it less fatiguing diving multiple dives with Nitrox fills.

mselenaous · Jul 14, 2014

swimmer_spe:
So, If I plan between 60-80 feet, I can hypothetically last longer on Nitrox?

On a Liveaboard the dive sites are planned along their route. You won't necessarily have the option of choosing your depths, however the dive crew are very adept at planning these profiles already since they have dove them alot. Follow their recommendations for depth & time but stay well within the limits of your computer. And enjoy your long surface intervals. Nitrox may or may not extend your dives, it will extend your NDLs. Chances are your dives will be limited more by your air supply than NDL.
And don't feel like you HAVE to do every single dive if you are tired. It is ok to skip a dive to enjoy the sundeck with a good book...it is YOUR vacation.

00wabbit · Jul 14, 2014

swimmer_spe:
So, If I plan between 60-80 feet, I can hypothetically last longer on Nitrox?

To answer your question:
With nitrox you aren't going to physically breathe any differently. So you will consume it at the same speed you consume air. Considering that you have enough air that you will not run out, then yes nitrox will allow you to stay down longer before you hit your Ndls.

This is will be especially more evident on the 2nd, 3rd and 4th etc dives of the day because you will carrying residual nitrogen from previous dives. Your computer will start cutting these dives shorter because of this. Diving nitrox will decrease your nitrogen loading somewhat so if your computer is set properly for nitrox it will allow for longer times before ndl.

Nitrox

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swimmer_spe

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