Is nitrox worth it for deeper rec dives?

[CAPTAIN SINBAD]

Yes but I am at work and I don’t want to be caught doing EAD calculations

 

[Storker]

Yes but I am at work and I don’t want to be caught doing EAD calculations

But you're going home sometime tonight, no? It oughtn't take much more than some ten minutes for someone EAN certified, even if they only have access to a pocket calculator, a pen and a few sheets of paper.

 

[CAPTAIN SINBAD]

But you're going home sometime tonight, no? It oughtn't take much more than some ten minutes for someone EAN certified, even if they only have access to a pocket calculator, a pen and a few sheets of paper.

Dude! It’s not for me. I know how EAD math works. Been there done that. I requested someone to post a table so that the OP could look at it and determine if Nitrox would be worth her wallet.

 

[tursiops]

so that the OP could look at it and determine if Nitrox would be worth her wallet

This is such a minor part of the decision matrix.

 

[Zef]

This is such a minor part of the decision matrix.

Depends on one's decision making paradigm.

-Z

 

[guruboy]

For people wondering what EAD is-

Equivalent air depth - Wikipedia

 

[BRT]

Somewhere in that decision has to be the cost per minute of diving at 130'. You gather up your thousands of dollars of dive gear and drive some distance to a boat. You pay the boat a fair amount of money to take you out to the wreck. You spend 8 minutes on the wreck at 130. Surface interval. Then what? Another 5 or 6 minutes for the second dive? Divide the money spent by the bottom time minutes and then do the same calcs throwing in the cost of a couple of tanks of 28% and the minutes that allows you. The value appears to me to be there.

 

[Jim Lapenta]

We can complicate this further by asking what PO2 is acceptable for 120-130 ft dives in 38-42 degree water. For me personally, I don't go above 1.3 for the working portion of the dive based on my level of accepted risk.
Sucks getting old.

There are benefits from a nitrogen loading standpoint in doing dives on nitrox when your buddies are on air. As long as you monitor your Po2 levels. For one, you have less residual nitrogen after that one-hour interval than those buddies. There's less physical stress on the body overall as it doesn't have to work as hard to get rid of the nitrogen.

What scares me about one of the comments is not limiting yourself to 110 ft. Without deco training. Just because you now have enough gas to go deeper, doesn't mean you should if you're qualified to handle the situation in an Oh Crap scenario. Plenty of non deco trained people who got themselves into trouble because they didn't want to take a conservative approach to deep dives.

These types of comments are why I don't accept every student that asks about tech training. Attitude towards safety and willingness to accept criticism and rules are just as important and the ability to hold a hover on deco for 10 minutes.

 

[Alan Browne]

I've going to have some deeper dives (110-130ft) this coming season. I'm wondering if nitrox is worth the cost for the wee bit of extra bottom time! I ran the numbers on my Perdix (medium conservatism). At 130ft with 28%, you only get 3 more minutes of NDL time than on air.

3 extra minutes is a lot on a 45 - 50 minute dive. 3 - 6 extra photos worth perhaps?

I'll be doing the EANx course this early Feb in advance of a planned trip in early March. I've read the PADI manual through twice with no issues on understanding.

My objectives:

• Learn something new.
• An excuse to finally buy a computer (borrowed one last trip and I am convinced).
• See if my air fish habits improve (doubtful).
• See if I feel better in the evenings after 3 dives/day and 6 days of it (I had to dump the last two dives of the last trip due to a headache - but I think that was more my sinus passages than anything else).

I'm not very convinced the increased NDL times will be of much use as the DM will set the pace. At this DC they're not especially anal about "lingering" divers once they know you and you've wrung out a few dives. Problem is finding a partner with a similar plan.

At this resort dives are mostly in the 60 - 90' band with only a few dives over 100'.

Dumb question for the experts: EANx gives me more oxygen, but it's CO2 that pushes my urge to breathe? Correct? So expecting more time before the bell tolls is not to be in the cards?

 

[Gareth J]

Dumb question for the experts: EANx gives me more oxygen, but it's CO2 that pushes my urge to breathe? Correct? So expecting more time before the bell tolls is not to be in the cards?

You are correct that it is the CO2 that pushes the urge to breath. (Or at least the change in PH in the blood caused by the CO2).
The extra O2 is really just offsetting the amount of Nitrogen in the gas. The body generates say 4-5% CO2, which is why Expired Air Resuscitation works (kiss of life), because you expel 16% O2, and 5% CO2 on each breath.

So using nitrox won't mean that you have additional gas in the cylinder because you used Nitrox. It is only extending your NDL (no stop time).
Even if you only have say 30 minutes of gas, and the NDL is 35 minutes. The first dive there is no benefit, but the benefit comes in a series of dives i.e day 2 or 3, when you have residual Nitrogen in your system which would limit your dive time. Using Nitrox, you are reducing the Nitrogen, so reducing the build up of residual nitrogen.