Overshooting NDL and mandatory deco stops

[Blackcrusader]

What is the back story here? Were they gas-limited rather than NDL limited? Did they get DCS? Did they have a computer? If so, did they violate THEIR computer or what yours said? Need more info to understand your denigrating statement.

One got the skin tingles DCS and needed some O2 after the dive. Yes they admitted going into Deco as they were on fun dives not with students. NO they are not using different gas just air not nitrox...

 

[Blackcrusader]

Why fact-check a good story?
Cool story, bro.

After 36 years of diving it's just the way I am. Your metabolism slows in ya old age. You don't need to sleep as much so the sleep apnea becomes less of an issue. You need to breathe less.

Actually I dive like a corpse. I barely move, I like to have the water carry me along even in the slightest of currents. I might not have to fin very often. I'm so relaxed I've had divers tug on my fins because they think I am an unresponsive diver. Listen to my breathing in this video. Check the time between breaths.... I sort of suck my air very slowly like as if you have your mouth closed with upper and lower teeth together and sip my air as needed. You breathe in 21% air and only use 6% so if you exhale everything immediately you waste a lot of air.

 

[Blackcrusader]

Another video taken by a DM for the dive center. You can see the bubble trails of the divers behind me. You can see a little bubbly trail from me as I constantly breathe out then a nice exhale, but then again I do very slow breathing in for maybe 10 - 15 seconds sometimes, I never fill my lungs up...

 

[rsingler]

Just to lend a second perspective to this...when I read body size and compared that to SAC, I said to myself, "hypercarbia?"
But I didn't want to rain on anybody's parade.

Now, having read

sleep apnea becomes less of an issue

things make a little more sense. I feel more confident in suggesting that this is a diver who is retaining CO2, but doesn't feel the panic that you or I might. I won't call it skip breathing, but I feel it's important that the casual lurker not look at this SAC, in this body size, and say, "I'm gonna try for that."

I do not believe this is a low SAC as you or I think of it. I believe this is normoxic (because of all the O2 molecules in air at depth) hypoventilation, rather than low metabolic rate.

Sorry, @BLACKCRUSADER , just an opinion that I feel obligated to share for other readers. And for you, I would suggest that at depth, in the event of a need for sudden exertion, what I think is an elevated CO2 places you at added risk. My 2¢.

 

[Blackcrusader]

Why fact-check a good story? Cool story, bro.

Why not? After all when I dive many people are very surprised at my air consumption. They wonder how I am so much better on air especially for my size. It's all about good diving techniques, it's how you dive not just how you breathe although that too is important.
I'm here to give them hope that they too will improve their air consumption and have longer dives, or be able to do deeper dive without fearing that they will be low on air quickly. The average diver I meet on vacations often does maybe 10 - 20 dives a year. I do around 150 - 250 plus a year. Last year was around 290 dives over 14 weeks doing 3 - 4 dives a day.

 

[Blackcrusader]

Just to lend a second perspective to this...when I read body size and compared that to SAC, I said to myself, "hypercarbia?" But I didn't want to rain on anybody's parade.

Now, having read , things make a little more sense. I feel more confident in suggesting that this is a diver who is retaining CO2, but doesn't feel the panic that you or I might. I won't call it skip breathing, but I feel it's important that the casual lurker not look at this SAC, in this body size, and say, "I'm gonna try for that."

I do not believe this is a low SAC as you or I think of it. I believe this is normoxic (because of all the O2 molecules in air at depth) hypoventilation, rather than low metabolic rate.

Sorry, @BLACKCRUSADER , just an opinion that I feel obligated to share for other readers. And for you, I would suggest that at depth, in the event of a need for sudden exertion, what I think is an elevated CO2 places you at added risk. My 2¢.

Thanks your insight is much appreciated.

I am well aware of not allowing CO2 buildup. every 2 minutes or so I will take a couple of deep breaths and fully exhale all the air in my lungs. In the event I need sudden exertion as in current diving I also have good techniques for diving either with or against the currents, they can sweep people up or down into the depths if they are not careful and know how to deal with them.

Thank you for sharing your opinion. I also live high up in the mountains near 10000 feet and then go diving several times a year. Being up at altitude sure is clean air living... I walk steep mountain trails every day for a few hours... hard yakka when the air is thin

I just about to head out for several hours for another nice stroll in the mountains.

 

[scubadada]

Hi Rob,

What do you think of my posted profile, hypercarbia? My average RMV for my last the last 1,432 dives is 0.36 +/- 0.04 cu ft/min. This covers a pretty wide variety of conditions. I am 5' 10", 185 pounds, hardly svelte.

 

[rsingler]

@scubadada , I can't really argue with either of you. The numbers you summarized, and the dive you posted is quite impressive, as are @BLACKCRUSADER 's numbers.

A standard 70kg male in my operating room will not retain CO2 with an RMV of about 5 liters/min (0.18 cfm). That's at rest, anesthetized. Studies say metabolic rate drops ~10% under anesthesia, so we might extrapolate to say, absolute basal requirements at complete rest are RMV 5.5 lpm, or 0.2 cfm.

Both you and Crusader could be doing this with no retention, a boatload of experience and lots of Zen.

Not many can match this without skip breathing. Now, if only we could measure end-tidal CO2 underwater.

 

[Graeme Fraser]

@scubadada , I can't really argue with either of you. The numbers you summarized, and the dive you posted is quite impressive, as are @BLACKCRUSADER 's numbers.

A standard 70kg male in my operating room will not retain CO2 with an RMV of about 5 liters/min (0.18 cfm). That's at rest, anesthetized. Studies say metabolic rate drops ~10% under anesthesia, so we might extrapolate to say, absolute basal requirements at complete rest are RMV 5.5 lpm, or 0.2 cfm.

Both you and Crusader could be doing this with no retention, a boatload of experience and lots of Zen.

Not many can match this without skip breathing. Now, if only we could measure end-tidal CO2 underwater.

Very interesting to have typical RMV figures for an anethetised 'average' male. Do you have figures for the average sleeping male as well? Clearly I have no medical training, but are there instances of sleepers retaining CO2, or does the body subconsciously regulate breathing more efficiently as opposed to a person consciously skip-breathing or overexerting?

Sorry if what I'm saying is pure nonsense; it kinda made sense to my little brain .

 

[Blackcrusader]

@scubadada , I can't really argue with either of you. The numbers you summarized, and the dive you posted is quite impressive, as are @BLACKCRUSADER 's numbers. A standard 70kg male in my operating room will not retain CO2 with an RMV of about 5 liters/min (0.18 cfm). That's at rest, anesthetized. Studies say metabolic rate drops ~10% under anesthesia, so we might extrapolate to say, absolute basal requirements at complete rest are RMV 5.5 lpm, or 0.2 cfm.

Both you and Crusader could be doing this with no retention, a boatload of experience and lots of Zen.

Not many can match this without skip breathing. Now, if only we could measure end-tidal CO2 underwater.

I just had surgery last month and even my surgeon said he was really surprised about my breathing and lower than expected heart rate bpm. He asked me did I do a lot of sports when I was young and I did. I spent 9 days lying on the slab with my legs raised...
Maybe as you said it's that boatload of experience and lots of Zen. I've even been accused of taking naps on my dives. For me diving is like taking a rest.. Being on a dive is where I can really chill out and not think about anything. Call it the zen mode if that's what it is... I'm just totally relaxed...