Another lesson learned today

Nwbrewer · Post by **Nwbrewer** » Mon Mar 26, 2012 9:59 am

Jeremy wrote:
I agree that even on air narcosis is a legitimate concern.

What does that mean? I've been to the boat in light EAN mixes and on air. After the last time where I spent 1/2 the drop kicking against the current and had a good CO2 buildup by the time I hit the bottom, I won't be back without He. Based on the fact that the boat is (imo) pretty lame, I won't be back.

Jeremy · Post by **Jeremy** » Mon Mar 26, 2012 10:01 am

Nwbrewer wrote:
Jeremy wrote:
I agree that even on air narcosis is a legitimate concern.
What does that mean? I've been to the boat in light EAN mixes and on air. After the last time where I spent 1/2 the drop kicking against the current and had a good CO2 buildup by the time I hit the bottom, I won't be back without He. Based on the fact that the boat is (imo) pretty lame, I won't be back.

Air doesn't have the same pp02 risk as EAN32, but narcosis is still a concern.

lamont · Post by **lamont** » Mon Mar 26, 2012 10:04 am

Jeremy wrote:
kdupreez wrote: Call me crazy, but I say rather err on the side of caution.. I'd much rather come back and do the dive again with the right gas, than play Russian roulette and end up unlucky..
A 100ft maximum depth on non-helium mixes just seems very conservative and makes a visit to the boat a very expensive dive to do properly.

But I agree, the conservatism makes sense and there is no reason to take a crazy risk just to go look at an unimpressive boat.

I guess I'm having a hard time getting out from the "lot's of other divers go to the boat on air, why can't I?" thinking. I think I'll stick to the 100ft max going forward.

You can do that right up until the point where you get stressed at 120 without helium. It is when something goes wrong with the gear, or you get hit by weird currents at depth that you're going to notice it. You'll build up CO2 and will take a substantially harder narcosis hit on that dive, in addition to whatever problems you're having at depth. Helium cuts through that two ways, one by displacing nitrogen and reducing narcosis directly, and the other by reducing the viscosity of the gas you are breathing, reducing the effort required to breathe which allows you to expel CO2 more efficiently. The third thing is that you should get into cardiovascular shape to increase your bodies ability to blow off CO2 better -- which is how the GUE program all comes together into a bigger picture (and eventually add scooters to handle currents and reduce workload and avoid CO2 even more).

Jeremy · Post by **Jeremy** » Mon Mar 26, 2012 10:07 am

lamont wrote:
Jeremy wrote:
kdupreez wrote: Call me crazy, but I say rather err on the side of caution.. I'd much rather come back and do the dive again with the right gas, than play Russian roulette and end up unlucky..
A 100ft maximum depth on non-helium mixes just seems very conservative and makes a visit to the boat a very expensive dive to do properly.

But I agree, the conservatism makes sense and there is no reason to take a crazy risk just to go look at an unimpressive boat.

I guess I'm having a hard time getting out from the "lot's of other divers go to the boat on air, why can't I?" thinking. I think I'll stick to the 100ft max going forward.
You can do that right up until the point where you get stressed at 120 without helium. It is when something goes wrong with the gear, or you get hit by weird currents at depth that you're going to notice it. You'll build up CO2 and will take a substantially harder narcosis hit on that dive, in addition to whatever problems you're having at depth. Helium cuts through that two ways, one by displacing nitrogen and reducing narcosis directly, and the other by reducing the viscosity of the gas you are breathing, reducing the effort required to breathe which allows you to expel CO2 more efficiently. The third thing is that you should get into cardiovascular shape to increase your bodies ability to blow off CO2 better -- which is how the GUE program all comes together into a bigger picture (and eventually add scooters to handle currents and reduce workload and avoid CO2 even more).

This makes sense, I totally agree.

Joshua Smith · Post by **Joshua Smith** » Mon Mar 26, 2012 10:20 am

Jeremy wrote:A 100ft maximum depth on non-helium mixes just seems very conservative and makes a visit to the boat a very expensive dive to do properly.

Completely agree. Been there on air many, many times. Not for everyone, I know. But nothing at all wrong with it for an experienced diver.

Nwbrewer · Post by **Nwbrewer** » Mon Mar 26, 2012 10:39 am

Jeremy wrote:
Nwbrewer wrote:
Jeremy wrote:
I agree that even on air narcosis is a legitimate concern.
What does that mean? I've been to the boat in light EAN mixes and on air. After the last time where I spent 1/2 the drop kicking against the current and had a good CO2 buildup by the time I hit the bottom, I won't be back without He. Based on the fact that the boat is (imo) pretty lame, I won't be back.
Air doesn't have the same pp02 risk as EAN32, but narcosis is still a concern.

Gotcha, just making sure you weren't implying that EAN was more narcotic than air.

lamont · Post by **lamont** » Mon Mar 26, 2012 10:52 am

Jeremy wrote: This makes sense, I totally agree.

just for completeness, detail that i forgot on my way out the door to work was that horizontal trim and strong efficient kicks also tie into being able to move through the water with a minimum of effort and a minimum amount of CO2 buildup, which gives you more bandwidth to deal with current at depth... then add fitness, scooters, helium, etc...

CaptnJack · Post by **CaptnJack** » Mon Mar 26, 2012 10:56 am

Jeremy wrote: Just to be clear, the "plan" was to go to 125 on air. The second dive to 60ft was going to be done on Nitrox. My buddy confused the gases which I would have caught if I had done a predive.

The goals and gases for the dive were all discussed prior to the dive. Obviously there was a misunderstanding.

Why was it your responsibility to say "I don't have a suitable gas for this dive"?

I don't really know what your discussion was like, but someone didn't understand the feedback. Whether that message was a blank look or whatever.

Jeremy · Post by **Jeremy** » Mon Mar 26, 2012 11:00 am

CaptnJack wrote:
Jeremy wrote: Just to be clear, the "plan" was to go to 125 on air. The second dive to 60ft was going to be done on Nitrox. My buddy confused the gases which I would have caught if I had done a predive.

The goals and gases for the dive were all discussed prior to the dive. Obviously there was a misunderstanding.
Why was it your responsibility to say "I don't have a suitable gas for this dive"?

I'm not sure what you mean. I'm responsible for my own gases and didn't want to dive the first dive on Nitrox.

CaptnJack · Post by **CaptnJack** » Mon Mar 26, 2012 11:20 am

Jeremy wrote:
CaptnJack wrote:
Jeremy wrote: Just to be clear, the "plan" was to go to 125 on air. The second dive to 60ft was going to be done on Nitrox. My buddy confused the gases which I would have caught if I had done a predive.

The goals and gases for the dive were all discussed prior to the dive. Obviously there was a misunderstanding.
Why was it your responsibility to say "I don't have a suitable gas for this dive"?
I'm not sure what you mean. I'm responsible for my own gases and didn't want to dive the first dive on Nitrox.

I know I meant shouldn't your buddy have said "wait I have the nitrox tank on right now"? At some point either on the surface, at 60ft when you went past the other dives plan (if he got them backwards), or at 100ft or somewhere other than the parking lot afterwards.

Jeremy · Post by **Jeremy** » Mon Mar 26, 2012 12:16 pm

CaptnJack wrote:I know I meant shouldn't your buddy have said "wait I have the nitrox tank on right now"? At some point either on the surface, at 60ft when you went past the other dives plan (if he got them backwards), or at 100ft or somewhere other than the parking lot afterwards.

Yes, absolutely. I even withheld my analyzer from him, but he still geared up with Nitrox. To me, you don't dive Nitrox that you haven't analyzed just prior to the dive. That was his first dive with Nitrox and his Nitrox class was back in October. I'm sure he was very fuzzy on the subject.

loanwolf · Post by **loanwolf** » Mon Mar 26, 2012 12:40 pm

kdupreez wrote: The problem with O2 toxicity is that "we just dont know".. as in we dont know why it happens and why some people get hit much sooner than others (if at all) and why the same person gets hit at random PO2 levels and random exposure times on different days.. Back in WW2, Prof. Kenneth Donald spend well over 3 years of dedicated research on this subject and after thousands of human trails, the research was deemed "inconclusive".. i.e. unpredictable and root cause unknown.
.

Part of it they do know today. .4 - 1.25 is considered unlimited for commercial purposes. You can stay for days/months at that. What they have identified is that a person who has any systemic disease that effects the metabolism or if you take any medications or drugs that alter the metabolism you are much more likely to be predisposed to take a hit at PO2's above 1.3. Most people are not predisposed to it so longer O2 exposures have very little chance of effecting them. They are not sure of the biochemical changes in the brain that cause it. No one will volunteer for the testing that needs to be done.

CaptnJack · Post by **CaptnJack** » Mon Mar 26, 2012 12:46 pm

We've all had some "oh crap" dives so wouldn't beat yourself up too bad. Going forward I'd focus less on "analysis, analysis, analysis" and more on how you discussed a plan yet misunderstand each other at 1 ata so much, or at least miscommunicated the nuances. If you miscommunicated at the surface, you weren't going to redo the plan correctly once you descended.

kdupreez · Post by **kdupreez** » Mon Mar 26, 2012 4:58 pm

+1 on what Richard said, dont beat yourself up too much.. it was a good learning experience to communicate all parameters of you dive plan on the surface when you can talk freely

ljjames · Post by **ljjames** » Mon Mar 26, 2012 5:26 pm

Withholding the analyzer (if i read that right) could come off as a bit odd (read: passive aggressive).

Catching flies with honey is easier

In this crazy world where a tank could have a range of mixes in it, folks swapping tanks, and loaning tanks, getting each others tanks filled at stations that pump nitrox, air and whatnot, it would not be unheard of (in fact, encouraged) to analyze all your breathing gas all the time prior to the dive. I'll actually offer up my analyzer at the dive site nonchalantly. "need it?"

This would also take some of the "just took the fundies epiphany/new-different style of diving" out of it. Let them just think you are insanely OCD

If you ask them to analyze theirs, you can use what you've already stated... "In the case of an emergency, it's my breathing gas too, so pretty please? humor me?"

You can integrate this 'new' way of diving with your previous dive buddies... just do it gently

He may or may not have been fuzzy on it. As you read here, there are lots of 'opinions' regarding MOD etc. I mean he could be, (you know him, i don't) but he could also have been brushing up online and looked at some old literature like previous NOAA tables that say 32% is good to 130' and 36% to 110.

Mind you i'm not advocating using 1.6 for working portion of dive, I'm simply pointing out that there is still content on the internet that shows 1.6 as a MOD, so if someone did a search for nitrox tables, there is a likelihood that these could pop up.

(for example)

http://www.ndc.noaa.gov/pdfs/nitrox36.pdf

http://www.ndc.noaa.gov/pdfs/nitrox32.pdf

+ about 5 or 6 to everything rjack has posted here.

Jeremy wrote:
CaptnJack wrote:I know I meant shouldn't your buddy have said "wait I have the nitrox tank on right now"? At some point either on the surface, at 60ft when you went past the other dives plan (if he got them backwards), or at 100ft or somewhere other than the parking lot afterwards.

Yes, absolutely. I even withheld my analyzer from him, but he still geared up with Nitrox. To me, you don't dive Nitrox that you haven't analyzed just prior to the dive. That was his first dive with Nitrox and his Nitrox class was back in October. I'm sure he was very fuzzy on the subject.

lamont · Post by **lamont** » Mon Mar 26, 2012 5:58 pm

ljjames wrote:Withholding the analyzer (if i read that right) could come off as a bit odd (read: passive aggressive).

yeah, and you should analyze tanks that are suspected to only be 21% as well and validate that it really is air. i'd probably do that out of habit even if the shop only pumped air and there wasn't a T-bottle of O2 within 1,000 feet of the tanks when they were filled. of course, i don't typically get fills at shops that only pump air, but that is encroaching on a whole 'nother can of wurms...

and, so he dove a nitrox tank which hadn't been analyzed? or hadn't been analyzed recently? did he analyze it at the shop or did he trust the shop to analyze it correctly?

if it had analyzed out to 38% that would be getting into a whole more interesting ballgame of pushing ppO2... which is how things can spiral... he doesn't analyze, you don't loan him your analyzer, he dives it assuming it is 32% then you push it down to 125, then it turns out its 38%, then you hit some current and workload... and that's is how an accident chain starts, or how you start to spiral around the incident pit...

Jeremy · Post by **Jeremy** » Mon Mar 26, 2012 6:53 pm

Withhold was probably too strong. He asked me for my analyzer and I said lets wait until you have the tank set up in your BC because my analyzer attaches to the BC hose.

He never asked for it after that and I wasn't expecting him to since we were just diving air.

The nitrox was analyzed at the shop the previous day though.

lamont · Post by **lamont** » Mon Mar 26, 2012 7:06 pm

Jeremy wrote: The nitrox was analyzed at the shop the previous day though.

by him? by the shop? did he see the analyzer?

i prefer to analyze the day of the dive with my own analyzer.

just yesterday, i took a set of doubles i had filled on 3/10 and slapped another piece of duct tape over that label and confirmed what i already knew, and then dove the tanks... doesn't matter that i knew they had been sitting in my garage untouched since they were filled and analyzed at the dive shop...

it really doesn't hurt you to re-analyze day of the dive and its a good habit.

i might not do that if its an early AM dive and there's a schedule to keep and i spent the night before loading gear in the truck and doing all my checks. sure. that's typically a tech dive, though, and it goes with assembling all the gear, checking all the pressures, analyzing all the gas, checking the argon fill, volt checking batteries, charging lights/scooters, etc. then analysis is part of the process of packing the truck for the dive...

spatman · Post by **spatman** » Mon Mar 26, 2012 7:12 pm

What benefit is there to analyzing your tanks right before the dive versus a couple days or even a week earlier when you picked them up from the shop?

Joshua Smith · Post by **Joshua Smith** » Mon Mar 26, 2012 7:41 pm

spatman wrote:What benefit is there to analyzing your tanks right before the dive versus a couple days or even a week earlier when you picked them up from the shop?

None, really. But Crap gets mixed up, sometimes. The more tanks you own, the greater the odds for a problem. That's what killed Carl Spencer on the Brittanic a few years back. I'm pretty anal about it, but I blend my own gas, and label it right there at my fill station. And even then, I re-verify my BO tanks every few months, just for peace of mind. This is one area you really can't be to careful in. Like Mel asked me more than once during class: "do you have a gas mass spectrum analyzer in your lungs? No? Ok, then, we'll do it my way."
Or words to that effect. Know wtf you're breathing, and know all the implications of breathing that gas.

kdupreez · Post by **kdupreez** » Mon Mar 26, 2012 8:00 pm

I analyze my tanks before I go dive them, on the day that I dive them... Analyzing at the dive shop and verifying whats in there, is the bare ass minimum that you should do if you dont own an analyzer.. But, I'd still be slightly skeptical.

If you analyze the tanks with the same analyzer that the shop used to do partial pressure blending and the analyzer happens to not working properly due to either a faulty/old sensor or electronics issue or flow issue or any other issue, then all that you are doing is confirming the same faulty reading that the shop slapped on there. If you analyze with your own analyzer at the dive site and its waaay off then something is wrong..

If you tell me you have a headache and I reach in my pocket and give a handful of some weird ass yellow tablets and say take four of them and you'll be good.. Will ya trust me?? probably not unless you can verify what they are and what dosage you should take.. And that wont even kill ya.. toxing at a 100ft will..

Complacency kills.. So why not remove all the variables that you possibly can out of the equation in order to stack the favors in your odds..

spatman · Post by **spatman** » Mon Mar 26, 2012 8:48 pm

kdupreez wrote:I analyze my tanks before I go dive them, on the day that I dive them... Analyzing at the dive shop and verifying whats in there, is the bare ass minimum that you should do if you dont own an analyzer.. But, I'd still be slightly skeptical.

If you analyze the tanks with the same analyzer that the shop used to do partial pressure blending and the analyzer happens to not working properly due to either a faulty/old sensor or electronics issue or flow issue or any other issue, then all that you are doing is confirming the same faulty reading that the shop slapped on there. If you analyze with your own analyzer at the dive site and its waaay off then something is wrong.

I own an analyzer and always check my own tanks. My question was whether there was any difference between analyzing my tanks the day I got them from the shop compared to the day of the dive, whether that was a couple days or a week or more.

LCF · Post by **LCF** » Mon Mar 26, 2012 8:54 pm

spatman, I think that's a good question, and I'm not sure there's a good answer.

The folks who trained me say analyze every tank the day you dive it. I don't do that.

When I picked up tanks at the shop, we analyzed every tank there and labeled it. Tanks came to our house and remained there. So long as a tank had the analysis sticker we put on it, I was willing to dive it, no matter how long it had been sitting. Our tanks are never mixed with anybody else's.

I'm sure there is some kind of risk involved in that, but I have been willing to take it.

Now that we are filling our own tanks, and not analyzing them at the shop or together, I'm getting more worried about what's in the tank, and more tanks are being analyzed at the dive site.

doublesunder · Post by **doublesunder** » Mon Mar 26, 2012 9:06 pm

Joshua Smith wrote:
Jeremy wrote:A 100ft maximum depth on non-helium mixes just seems very conservative and makes a visit to the boat a very expensive dive to do properly.
Completely agree. Been there on air many, many times. Not for everyone, I know. But nothing at all wrong with it for an experienced diver.

+1, Well defined Josh

kdupreez · Post by **kdupreez** » Mon Mar 26, 2012 9:24 pm

doublesunder wrote:
Joshua Smith wrote:
Jeremy wrote:A 100ft maximum depth on non-helium mixes just seems very conservative and makes a visit to the boat a very expensive dive to do properly.
Completely agree. Been there on air many, many times. Not for everyone, I know. But nothing at all wrong with it for an experienced diver.
+1, Well defined Josh

To each his own.. But I owe it to my dive buddy to do that dive on a mix that I'm assured will not impair my judgement or cognitive thinking.. I dont want to make stupid mistakes when I get task loaded at 120' when the crap hits the fan.. i.e. when I need to save my buddy's life... And I expect my dive buddy to do the same for me.

If I drink 6 beers and drive the exact same five blocks from the bar to my home everyday, I'll be very experienced in making that trip.. even while fairly intoxicated. and I would be able to make the trip with my eyes closed giving me a nice warm cozy false sense of security.. until the day that a kid crosses the road unexpectedly.. Then my neuromuscular responses will fail me, no matter how well I know that road..

just like I dont drive drunk.. I dont dive drunk..

Northwest Dive Club