Nitrox 32 first dive, air second dive?

[redacted]

I probably have about 400 dives in Cozumel, usually doing 3 and sometimes 4 dives per day on a fairly liberal computer. On two tank morning dives I do have to manage gas loading as I try to limit myself to less than 85% of my allowed NDL loading. I do not use nitrox in Cozumel. While it would be a small addition to the total trip cost, so far I have saved enough by not diving nitrox unnecessarily to pay for 2 additional trips. I usually only use nitrox when it is free or when it is necessary to conduct the planned dives.

 

[Joneill]

I believe Meridiano charges an additional $12 per tank for nitrox. Also I didn't see the tanks analyzed. You have to accept that the tank actually has the marked mix - or not.

To use Nitrox responsibly (and per your training) - you need to analyze your tanks yourself. You should NEVER assume a tank is marked correctly - could be deadly to do so...

 

[AdivingBel]

Diving daily 2-tanks, I dive air in Coz. Only reason I'm sayin' is 'cause the op asked. Everybody has their reasons that work for them.

 

[MMM]

Thank you Tursiops.

My question is:
What do other divers (Cozumel Nitrox certified veterans diving AL80's) do for their two dives?
This question I cannot ask myself. I am simply asking for the collective experience of the regulars to Cozumel. Thank you

I dive on a steel 95 and dive air on the first dive (since it's where we will likely go deepest) and nitrox 32 on the 2nd dive. Always. Doesn't matter what anyone else on the boat is diving. If they are all on air, I may go a bit deeper than them (since they are staying shallower to manage their NDL) or I may stay with them and consider it an additional safety bonus. Or, the DM will send everyone else up who is on air, and the rest of us on nitrox continue our dive until someone runs low on air.

 

[BRT]

Last year, diving on air in Cozumel for 6 days we came very close to deco obligations on our computers. Something we would like to avoid going forward. We dive AL80's generally.
We are diving in March for 7-8 days and will be doing the usual 2 dives per day, with a night dive mid week (followed by an off day).
It makes sense to me do dive Nitrox 32 on the first dive, as it is usually the deeper one of the two.
My question is regarding the second dive. We could dive Nitrox 36 (as the second dive is generally more shallow), or we could dive air, knowing that we have plenty of recovery time after the second dive.
We tend to do dives around 55-65 minutes following the usual Cozumel dive profiles. We are diving with 3P.
In your opinions, what does diving the second dive on Nitrox 36 buy me vs. diving the second dive on air?
I'm not opposed to shell out the extra $10 per tank, but I'd like to see what other veterans of Cozumel diving AL80's generally do on two tank days. In other words, is it worth it?
Thanks in advance.

We no doubt have seen you or been on the boat with you as we are diving with 3P right now. We are diving 32% and then 32 or 36 depending on what they can get. I think the second tank could be air most of the time but just possibly today on the French Lady we would have been pushing NDL's. I'm willing to pay for the nitrox just to stay far away from limits.

 

[amoses]

I have always dove EAN21 on both morning tanks. I have got into the yellow a couple of times on my Oceanic computer, but with proper management I have never exceeded NDL. I do always watch it close and I do try to spend extra time at the safety stop if possible.

 

[ggunn]

Only thing about Nitrox is that you don't get that tired, washed out, feeling after diving.

That's very subjective. I don't notice any difference.

 

[redacted]

That's very subjective. I don't notice any difference.

I thought I felt some difference at the Flower Gardens but that was somewhat more challenging diving.

 

[Andrew Donn]

$70 over 7 days is money well spent on an additional factor of safety. Of course it depends on your specific profiles but I think the point that the OP is getting at is that the second dive is limited by gas volume or constraints set by the dive master or boat and not the NDL. Even is that is the case multiple dives over multiple days have a cumulative effect on gas loading that the computer and table models do not take into account sufficiently. At two dives a day it is probably not a big issue but the nitrox on the second dive would add to the safety factor over multiple days. This would be more of a factor if doing 4 or more dives a day.

 

[doctormike]

To answer this question, I always dive nitrox in Cozumel -
Thank you DoctorMike. Would you mind sharing the percentages you typically use?

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