To Nitrox or not to nitrox ,Why and how ?

[rhwestfall]

A little help guys:

I'm returning to this sport after 8 years of non-participation, and back when I was diving a bunch, EAN wasn't really in the forefront around here. Seems now it is.....

For 20+ years, I've dove "air".......

From reading all this, can I say that with my diving around here (115'-125' normal opportunities on wrecks), its pointless to pursue Nitrox training/certification? The way we dive (usually 2 dives a day, with long SI's - its my boat, and my schedule), it isn't like a Bonaire week - and even on a trip to there we do 3 a day..... vacations are to relax...

am I missing something?

 

[Tortuga68]

According to the table posted earlier you're going to increase your BT by 25-65% (disregarding the disputed figure)

So it depends whether you think that's worthwhile

 

[doctormike]

From reading all this, can I say that with my diving around here (115'-125' normal opportunities on wrecks), its pointless to pursue Nitrox training/certification? The way we dive (usually 2 dives a day, with long SI's - its my boat, and my schedule), it isn't like a Bonaire week - and even on a trip to there we do 3 a day..... vacations are to relax...

am I missing something?

Yup, I think that you are.

Lets use the PADI numbers. If you dive to 120 feet on air, you will have a total of 26 minutes actually diving on the wreck out of what is usually a whole day's project (from loading gear in the AM to hanging up your gear to dry after rinsing in the PM). If you use EAN 32, you will have 40 minutes on the wreck. To me, that's a significant advantage, when considering the costs.

For you to make the decision, you would need to do your own cost-benefit analysis.... so let's see what the downside is:

1) Training - a very quick and easy course, that shouldn't cost much. Looks like somewhere between $70-$200 by this thread.

2) Gas costs - $8-15 per tank, as compared to $4-6 for air. So maybe at most an extra $25. Not much when you consider the other ongoing costs of diving. If you have your own boat, how much does it cost to drive to the wreck site?

3) MOD - If your wrecks are deep with high relief, and you don't have a hard bottom that is less than your MOD, you potentially risk not being able to swim down if you see something interesting below that depth. I keep my tanks filled with EAN 28, so that I'm OK for any depth that I would normally be hitting if I get an unplanned opportunity to dive. Since you said that your dives are 115-125 feet, you would probably be OK.

Not sure what the great advantage of sticking with air would be, but of course it is a personal decision!

M

 

[String]

From reading all this, can I say that with my diving around here (115'-125' normal opportunities on wrecks), its pointless to pursue Nitrox training/certification? The way we dive (usually 2 dives a day, with long SI's - its my boat, and my schedule), it isn't like a Bonaire week - and even on a trip to there we do 3 a day..... vacations are to relax...

am I missing something?

Depends...Are you ending the dives due to NDLs running out or is it air or other reasons? If its the former nitrox will help, if its the latter than nitrox will make no difference other than an increased cost and shallower maximum permitted depth.

 

[Blackwood]

According to the table posted earlier you're going to increase your BT by 25-65% (disregarding the disputed figure)

So it depends whether you think that's worthwhile

And that percentage increases with repetitive dives.



Also, here are images of NAUI 32 and 36 tables:

http://www.nitroxdiver.com/Library/tables.html

Note they both go to 1.6 (for better or worse) and that on 32 NDL is indeed the same at 110 and 120. My first guess is that the table was built by modifying air tables using equivalent air depth with creative rounding rather than by a full algorithmic output (and that thought is ringing some bells about NAUI's tables being USN-derivatives).

 

[doctormike]

Depends...Are you ending the dives due to NDLs running out or is it air or other reasons? If its the former nitrox will help, if its the latter than nitrox will make no difference other than an increased cost and shallower maximum permitted depth.

Yes, that's true... I was assuming that he was ok with gas consumption. But in most cases (unless you are really draining the tanks quickly) nitrox will also let you run shorter SIs and still get acceptable NDL on the second dive.

 

[CuNanoTube]

If I spend $50 on a dive (x however many), $60 on gas to get there and back, and $60 on a hotel room, I am sure as hell using whatever means I can to extend bottom time. This is why I dive nitrox. Plus most diving I do is in to 80' plus range, so there is an advantage to using it. I also do a custom mix for each dive if possible.

I should also note a nitrox fill costs $10 where I get my fills.

 

[rhwestfall]

Thanks for the comments guys. Pardon my ignorance on EAN, but you are saying that there are different ratios "normally" obtainable/pumped an a LDS (yes, I'll need to see what they offer)? In the last few posts, I'm seeing 21 (normal air), 28, & 32. Others?

Based on planning of adding additional depth (10' due to cold), My hard bottom is 135' - theoretical.

Following the math examples provided (1.4 MOD),

21 = 187' (so 135' is "reasonable" for use)
EAN 28 = 132' (okay, close at 1.4 MOD) Is this an issue to those trained?
EAN 32 = 111' (doesn't work)

yet you say "okay" - what am I missing? Before I go pay for a class that won't benefit me, I wan't to understand...

 

[oldogre]

I must dive in Heaven, I pay 25Euro (about $36) for a RIB Dive, about 50mins, with a single tank - supplied - with air or 32%!

 

[doctormike]

Thanks for the comments guys. Pardon my ignorance on EAN, but you are saying that there are different ratios "normally" obtainable/pumped an a LDS (yes, I'll need to see what they offer)? In the last few posts, I'm seeing 21 (normal air), 28, & 32. Others?

Based on planning of adding additional depth (10' due to cold), My hard bottom is 135' - theoretical.

Following the math examples provided (1.4 MOD),

21 = 187' (so 135' is "reasonable" for use)
EAN 28 = 132' (okay, close at 1.4 MOD) Is this an issue to those trained?
EAN 32 = 111' (doesn't work)

yet you say "okay" - what am I missing? Before I go pay for a class that won't benefit me, I wan't to understand...

EAN is available blended at any mix you need, provided that your dive shop doesn't just sell banked 32 or 36.

I just got back from a trip to North Carolina, where the shop banked EAN 30, based on the dive profiles in the area. At home, I tend to keep my tanks filled with 28, just to be on the safe side, since I don't know ahead of time where I will be diving. Certainly, if you know where you are going to dive when you get your tanks filled, you would choose the richest mix that would be safe (by MOD) at that dive, to get the most advantage in terms of NDL, safety or SI.