Current Status of Fill Station Owned/Operated by Stathis

[ReefHound]

We haven't had this argument on the Coz board in so long. I missed it. So if I dove air and was forced up by a lack of bottom time or instead I switched to nitrox and was forced up by a lack of gas with plenty of bottom time left, would that not indicated that on the second dive I ended with less nitrogen loading which would indicate a higher margin of safety?

That's a presumption you were forced up by gas. In my experience in Coz, most people are already at 50' or less when they reach low on air. At what depth do the two factors cross for you?

If we want to go that route, it would be much safer for us to all dive 63cf tanks.

 

[cvchief]

That's a presumption you were forced up by gas. In my experience in Coz, most people are already at 50' or less when they reach low on air. At what depth do the two factors cross for you?

If we want to go that route, it would be much safer for us to all dive 63cf tanks.

That presumption is a reasonable one. Nitrox = Longer bottom time = more gas consumption = more chance of available gas running low. There would unquestionably be diver running low on gas during the increase amount of bottom time.

As for smaller tank, that is going a different direction. Limiting dive time by available gas would increase safety, but what I am talking about is adding safety and dive time. Which of course if varible, ie if you if the time you add is limited by available BT, you haven't added safety, but if it is limited something else, you have.

I dive a Mares so I am already using a conservative profile. For a while I dove 100 air to keep up with the missus who would run about anyone you pick outta gas. So I slammed up against NDL every dive pretty much. Since I discovered 32% 100 rentals, I can comfortable keep up with her until she get cold most of the time with lots of NDL left. Occasionally, I get that close to NDL but for the most part I have BT left, unlike air. Hence I conclude my nitrogen loading is in fact less.

Now on your 50 foot thing, I'm kinda lost on what you are saying. I agree that as people are getting low on air the group tend to move to an area that has some shallows, but if I hanging at the bottom of the area at 70 feet, while the soon to go up peeps are floating 10 foot above the reef at 50, I don't know how that enters into it? Also a general rule I tend to be on the lower side of the group a lot, which contributes to eating more BT and gas. But there are some many little cool things down there....

I digress, but my point is, for the same dive profile, as we increase available BT, more people will run out of gas. So for all of us who fit that, you have to agree we are safer with less nitrogen loaded right?

 

[BRT]

No, "we" don't. When you say "we" are you talking about yourself? Because most people I know dive nitrox to extend bottom time and when you do that, if you've set your computer to your mix, you are approaching the same NDL and same nitrogen loading as when diving air.

Been through this forever. We dive longer bottom times and stay further away from NDL's than on air.

 

[cvchief]

Been through this forever. We dive longer bottom times and stay further away from NDL's than on air.

Yea, but its been a while.....

 

[ReefHound]

Now on your 50 foot thing, I'm kinda lost on what you are saying. I agree that as people are getting low on air the group tend to move to an area that has some shallows, but if I hanging at the bottom of the area at 70 feet, while the soon to go up peeps are floating 10 foot above the reef at 50, I don't know how that enters into it? Also a general rule I tend to be on the lower side of the group a lot, which contributes to eating more BT and gas. But there are some many little cool things down there....

I digress, but my point is, for the same dive profile, as we increase available BT, more people will run out of gas. So for all of us who fit that, you have to agree we are safer with less nitrogen loaded right?

What I mean by the 50' or less is that you start running into dramatically increased NDL times. No one diving air needs to surface because of NDL. They may need to ascend from 70' to 40', but at 40' on air your NDL is 140 minutes. Lots of 35-40' reef in Cozumel and most of the time that's where the DMs take the group after 30-40 minutes.

Theoretically less loading is better, but again I ask for the empirical evidence. As long as you are within the limits, any additional margin of safety is likely insignificant. If you are within the limits and get DCS it is probably not from nitrogen loading so would less loading have made a difference? It's like buying two tickets to the powerball lottery instead of one. You doubled your chances, which sounds impressive, but the chances either way are so low that you'll likely never see the difference.

 

[ReefHound]

Been through this forever. We dive longer bottom times and stay further away from NDL's than on air.

Maybe you should ask DAN to give you a 5% discount on dive insurance because you always dive nitrox.

 

[cvchief]

What I mean by the 50' or less is that you start running into dramatically increased NDL times. No one diving air needs to surface because of NDL. They may need to ascend from 70' to 40', but at 40' on air your NDL is 140 minutes. Lots of 35-40' reef in Cozumel and most of the time that's where the DMs take the group after 30-40 minutes.

Theoretically less loading is better, but again I ask for the empirical evidence. As long as you are within the limits, any additional margin of safety is likely insignificant. If you are within the limits and get DCS it is probably not from nitrogen loading so would less loading have made a difference? It's like buying two tickets to the powerball lottery instead of one. You doubled your chances, which sounds impressive, but the chances either way are so low that you'll likely never see the difference.

Ok, point one on the ascending to get BT, my experience is that once I slammed up against NDL I am SOL. I can go up 20 feet and go from 1 minute to 8 minutes, sure, but its ONLY 8 minutes. To use you later analogy that 8 TIMES the BT and it still sucks.

As to you second point, I must disagree. Theoretically? If you get DCS, it has to be from nitrogen right? So less of it has to be better? Even if you are gonna be bent within limits, there must have been a point where you loaded too much nitrogen for you body, so will less you might be under. As to the powerball, lets take that one for a spin. So say there are 70 minutes of BT on air and I used all 70 plus another 10, I have bought enough PB tickets that I shouldn't be surprised if I won a case of DCS.

Now if I was on Nitrox and there are 120 minutes of tickets (BT) and only stayed 70 minutes, I barely have half the PB tickets and am WAY less likely to win a case of DCS.

I think that is a terrible analogy, but I did the best I could... Easy on the next analogy, I think I sprained a cortex on that one.....

 

[ReefHound]

My experience is once you get to 30-35' the NDL goes to 99, regardless of mix or BT.

Whoa, there are 70 minutes of BT on air and you used all 70 plus another 10? That's a limits violation.

Where's the empirical data?

 

[ReefHound]

I should clarify that I am actually a big fan of nitrox and use it on most dive trips.

 

[cvchief]

My experience is once you get to 30-35' the NDL goes to 99, regardless of mix or BT.

Whoa, there are 70 minutes of BT on air and you used all 70 plus another 10? That's a limits violation.

Where's the empirical data?

I am not sure where the line is for serious increase in BT, I can only say my experience is when I blew it at depth, I needed to be close to snorkeling to get back a few minutes. My Mares watch actually I think has a laughing alarm when I look at it after running it down 1 m NDL and then going up to 40 feet. The screen I think flashed (Just stop. You did this. Get on the boat.) Maybe under 33 makes a diff? That could be. I have run over 2 hours on CS without an issue.

On the side note, why my Mares DEMAND 10 feet for a slight deco obligation is beyond me. Sure 9 and 11 count, but 12 does not. Then I can do my safety stop anywhere up to like 20. (And yes on THAT dive, my nitrox 32 was NOT safer than air, I just would have been doing the deco stop sooner.)

And yes, I used 80 minutes in 70. It was YOU analogy. I was trying to guarantee the PB win, er, DCS.... As to the empirical data, that was what I was trying to kindly call you out on to begin with.

And just to drive you crazy, you know I feel better and am less tired after a nitrox dive that is longer than an air dive that tired me out.

And more importantly, if I want to drink 3 strong margs at lunch at Moneybar RIGHT after I leave Fonatur while still in my dive clothes, how does my nitrogen loading affect that? Am I more or less likely to get bent? Or more importantly am I more or less likely to get drunk? These are the things that matter.

Speaking of which we should get together after a dive at Money with margaritas and discuss this in more detail. I would invited @Dave Dillehay because he always has an opinion but last time he accused me of trying to kill him with margs.