Tech Nitrox Intro

[Shooter Dan]

Finally, I'm stepping up for my Tech Nitrox Class. I've been diving up to 40% for about 7 yrs.

Most of my dives are 150' or above. Mostly spearfishing. I envision deco stops with 80% to off gas on. I'll do up to 7 dives in a day, most in the 100' range.

Any gear tips for my new setup? I'm looking at a Zegal 500tech reg and a new 30 pony.

How would you do it and What have you learned from your experience?

Standing by.

[Uncle Pug]

You talk spearfishing.... but all I've seen you do is troll.

[Shooter Dan]

Now that's a well thought out reply. What in this post seems to give you that impression?

I have Nitrox Questions, If you can't keep a thread alive and informative.

Jump off the deepend, I have extra weights for you!

[omar]

Hmmm......

7 dives a day that require deco would indicate that you will be out diving in excess of 16 hours a day.... Not likely or at most only once or twice followed by a long chamber ride.

So I would suggest a brain transplant for starters. Followed by extensive rehabilitation.


omar

[Wendy]

1-800-N0-BENDS

This is the phone number of a hyperbaric doctor in Florida, Dr. Ivan Montoya, M.D.

Just in case you end up needing it.

Also Don't forget the DAN number:

Diving Emergencies (Remember: Call local EMS first, then DAN!)
1-919-684-8111
1-919-684-4DAN (collect)
1-800-446-2671 (toll-free)


Hope this helps.

[Shooter Dan]

4 dives is average, but I've done 6 & 7 dives or bounces in a day.

That said, I'm here seeking knowledge for tech divers who are more experienced than I in higher mix O2.

I appreciate you looking for items in my post to crush a new member to this board. I'm sure you have plenty to choose from.

I can take it. If you want to sling some, come play in spearboard.com

I'm new to this board, but I want to thank you for stepping up and showing me who you are not. Helpful!

[drizzt117]

Guys, I think he gets the point about the DCS issue. I don't really have any knowledge when it comes to Technical Nitrox so I can't really be of any help. I just piped in because I think its stupid for people to write responses just to poke fun at someone. If you don't have something nice or constructive to say, don't say anything at all. Sorry for my rant.

Thomas

[Uncle Pug]

Shooter Dan once bubbled...
I'm new to this board, but I want to thank you for stepping up and showing me who you are not. Helpful!
I'll be helpful...

Your main concern should not be a DCS hit.

Your main concern should be the Ox Tox hit.

But then what do I know... what do any of us know... you have already been doing high PO2 dives for 7 years.

[Shooter Dan]

Hey Pugger,

Ease up brother. I've seen some of your post & I now you know your chit. If you can share it that's fantastic. Even with sarcastic tones, I will still learn from your knowledge.

As I stated in my first post. I am stepping up to Higer mix O2.

I normally dive 32-34%. On Deeper dives I us 27 or 28%. I'll learn MORE about O2 dangers from my instructor.

Thanks for the step up Drizz.

Hey Wendy. You must be aware that DAN doesn't give out Chamber information because if you rely on that and the chamber is down that leaves them in a liability position.

Are you recommending that we use your knowledge of available chambers?

If you’re coming to the dinner table, bring something to offer.

It was kinda funny!

Standing by for my next lashing.

[drizzt117]

Clarification to my original post:

I appeared to have spoken w/o previous knowledge. I agree that bashing is not acceptable on a board in which everyone wants to learn. But that comes from both sides.

After reading some of your other posts Shooter, I can understand why some others might be hostile toward you. Maybe you should tone down your responses a bit.

If you are truly looking for advice, then you are at the right place. If you are just here to cause trouble, go away.

Thomas

[Shooter Dan]

Ten Seconds......deep breath.....ten seconds.....deep breath.

OK!

[Uncle Pug]

Shooter Dan once bubbled...
I'll learn MORE about O2 dangers from my instructor.

And then maybe not... depends on what your instructor knows... and some don't know.

From what you've already mentioned I surmise that you will be learning to use high PO2s to deco after using high PO2s to minimize the risk of DCS on mulitple dives in the 100`150' range.

Just tuck this one away and let it guide you through the maze:

{The principle danger is going to be the Ox tox hit.}

[Jarhead]

Now I'll be the first to admit that I don't know anything about this, but...and feel free to correct me if I'm wrong...but don't you use a deco gas with a high ppO2 (such as 80%) for deco after a dive that you used and bottom gas (Trimix?) with reduced O2 percentage? (I'm not sure I stated that right).

As opposed to using a high O2% deco gas after using high O2% dive (bottom) gas as stated above.

[AquaTec]

Well I think you guys ran him off

[Big-t-2538]

But what I do know is that once you extend the PO2 above 1.4 to 1.6 you run a severe risk of getting an ox tox hit.

From my quick math, if you are diving to 150' the MAX O2% you should have is 28.8%...that works out to a PO2 of 1.6 ATA. For 100', max O2% is 39.6%

Thus, you say you normally dive 32 to 34% O2....and you normall dive to 100ft...that's an avg PO2 of 1.37....now according to my IANTD EANx text...the maximum recreational limits for O2 exposure at that PO2 in 24 hours is 180min....if your doing more than 4 dives...I think you might have exceeded this.

Anyway, this is just what I learned in my basic EANx class through IANTD. I wouldn't exceed these limits...you might want to check into an IANTD class?

As for more of my illustrious theories, if you are going to be using an 80% mix for DECO, I believe DECO stops are done at a high PO2 in order to off-gas, and you would be having to DECO at (approximately) 33 ft. as opposed to (I believe) 20ft. with 100% O2. I think most of the tech divers are now steering away from 80% for that reason, and using 70% for a deeper stop, then switching to 100% O2 for their final stop....I'm sure someone will correct me if I'm wrong.

Anyway, I too am going to be looking in the direction of deeper dive before too long...it seems to be interesting to me, but I am going to be sure I get some good education and knowledge before I jump in feet first.

[Shooter Dan]

AquaTec, is that all you can contribute?

I would expect more from a seasoned veteran, Yeh?

You are an instructor, right? I'll never do you type of diving and you probably won't be spearfishing and time soon.

My technical question was a reasonable one. Maybe too elementary for your level, but isn't that what these boards are for.

If you had questions regarding spearing a 70lb amberjack, I would try to add information that was worthwhile.

Although you didn't better this thread with your comment, you could if you wanted to.

If not that's fine, Sit back and enjoy the thread.

[omar]

The purpose of decompression gas(es) is to eliminate the inert gas dissolved in your tissues. This can be done by using a high FO2 gas at the appropriate depth. This would result in a PPO2 of 1.6 for a resting deco.

A deco gas of 80% oxygen is a poor choice for decompression because the balance is an inert gas that will reduce the effectiveness of the inert gas elimination by reducing the partial pressure gradient of both gases.

As Pug pointed out the primary concern would be an oxtox hit. It is critical that you have the right training to address this and have a buddy with you that has the skills to save your ass (and vice versa). Also you do not want to dive to high PPO2s over and over. You need to reduce the working PPO2, and plan the decompressions such that you are not accumulating an excess exposure. To do this use helium. The advantages of using helium for the depth and number of exposures you are talking about are innumerable and are the only sensible approach. A tech nitrox course is insufficient.

For extended profiles 50% is used at 70 FSW (and up) and 100%
at 20FSW

omar

[Uncle Pug]

Shooter Dan once bubbled...
AquaTec, is that all you can contribute?
...that chip on your shoulder is a huge snag hazard... you missed what AquaTec was saying by a mile! (as well as what the rest of us are saying of course.)

He was chastising us for running you off.... in that he was mistaken.... your not gone.... but be that as it may.... AquaTec was actually sticking up for you!

You just spit into the wind dude. :D

[AquaTec]

well i will thow in a couple of thoughts

Nothing wrong with 6 or 7 dives a day as long as you manage depth, time, and SI. Also I know that when I used to hunt it was always solo so if you are doing the same then buddy dependency is not an opption. just make sure you have some redundency

a tox hit probability can be reduced by reducing the Po2, but by doing so you will increase nitrogen loading which will increase fatiege and risk of dcs. you can walk this tight rope with good planning and management

I recomend using a nitrox computer that will track your CNS and dive profile for this type of diving. As for training, caring deco bottles etc, may not be conducive to the type of diving you are doing...hunting. I think that by watching your cns and managing other aspects of your diving, and getting a good nitrox computer to track cns etc you can do those dives

I know this because I used to do six dives a day at work as a dive guide at molokini island and then go do a couple of hunting/fun dives at night, using air...but that was a different
time. in those days my room mates and I only ate what we could get from the ocean and then suplement it with beer. sort of the hawaiian scuba instructors kraft dinner

[Shooter Dan]

What a great lunch. Did I write all of that stuff? Gezz that must have been hungry, evil Shooter Dan.

I respect your position and appreciate the information passed on. I'll be researching other posts on this topic and articles in prep for my class. As you can tell, words in print can be misconstrued or taken out of context.

Guys, I really didn't want to flounder and stir up the viz on my first dive here.

If you have any related articles or must know stuff, shoot it to me if you have some time.

Thanks

Standing by

[padiscubapro]

Big-t-2538 once bubbled...
But what I do know is that once you extend the PO2 above 1.4 to 1.6 you run a severe risk of getting an ox tox hit.

From my quick math, if you are diving to 150' the MAX O2% you should have is 28.8%...that works out to a PO2 of 1.6 ATA. For 100', max O2% is 39.6%

Thus, you say you normally dive 32 to 34% O2....and you normall dive to 100ft...that's an avg PO2 of 1.37....now according to my IANTD EANx text...the maximum recreational limits for O2 exposure at that PO2 in 24 hours is 180min....if your doing more than 4 dives...I think you might have exceeded this.

Anyway, this is just what I learned in my basic EANx class through IANTD. I wouldn't exceed these limits...you might want to check into an IANTD class?

As for more of my illustrious theories, if you are going to be using an 80% mix for DECO, I believe DECO stops are done at a high PO2 in order to off-gas, and you would be having to DECO at (approximately) 33 ft. as opposed to (I believe) 20ft. with 100% O2. I think most of the tech divers are now steering away from 80% for that reason, and using 70% for a deeper stop, then switching to 100% O2 for their final stop....I'm sure someone will correct me if I'm wrong.

Anyway, I too am going to be looking in the direction of deeper dive before too long...it seems to be interesting to me, but I am going to be sure I get some good education and knowledge before I jump in feet first.
I dont recommend 80% for a deco gas, depending on the profile using 50% from 70 feet or 100% at 20 are preferable..

If you are running high CNS loads you are much better on 50%, the time differance on hangs between o2 and 50% overall are minor and you get out of the water with a much lower cns. this said I always carry 50%as a deco gas (even when on a ccr for deco bailout). oxygen is useless to carry since you can only use it at 20ft or above.. if all goes well I'll do my deco on 50% and switch to o2 (hung below the boat or staged)otherwise I just finish it on 50%. Using both gases does decrease the decompression obligation since you started decoing deeper.. o2 by itself is only a marginal gain.. 80% is only 1 stop deeper and shorter than the 20ft stop.. so you really don't gain on the deco

[AquaTec]

padiscubapro once bubbled...

I dont recommend 80% for a deco gas, depending on the profile using 50% from 70 feet or 100% at 20 are preferable..


what do you have against 80%

I don't see it as an alternative to 50% it is an alternative to the 100% gas.

[Wendy]

What sort of profiles do you have on your dives? I know when you chase fish you may have a tendency to bounce a little in your depths. Are you doing these dives from a private boat?

[padiscubapro]

Big-t-2538 once bubbled...
But what I do know is that once you extend the PO2 above 1.4 to 1.6 you run a severe risk of getting an ox tox hit.


Not true.. The agencies take a more cautious approach now than in the past... I used 1.6 as a bottom gas for about a decade and in currents without incident..
ther is nothing wrong with going with a more cautious mix but above 1.4 isn't a magic number saying you'll otox.. There are alot of factors and total expossure time has to be taken into account.

Another fact there is only ONE documented case of a OTOX hit at 1.6 and this one is unclear as the person already had a history of epileptic attacks. I have had many dives with po2s higher than 1.6. I am not advocating using a 1.6 as a bottom mix just pointing out data doesn't support it as a danger.. If you are running long exposures it is probably prudent that you use a lower Po2 to stay within NOAA established normal exposure limits.. They also have a chart called exceptional limits which if you havent seen allow exposures and times considerably higher than the standard limits.

The NAVY uses a 1.8 with some of its rebreather divers!

Do some research yourself or find a knowledgeable instructor who knows more than the standard "text book responses". There is lots of reference material out there, a good starting point is the Navy manual..
BTW as you are reading youll find out most (all for nitrox)training agencies name trimix,heliox and nitrox incorrectly, they state ox-he or ox-nitrogen in the naming.. its not really oxyni or oxyhe is it??

The commercial industry, and the navy use intert gas then oxygen you don't see them calling a 84% heliox 16% oxygen mixture as heliox 16 its heliox 84-16.. also the navy calls nitrox 36 as nx 74-36.. ANDI follows this designation for trimix/heliox but goes with the recreational nomenclature for nitrox use.

Look at other commercial gas mixtures they are always presented with percentages in the way its named.

[roakey]

padiscubapro once bubbled...
also the navy calls nitrox 36 as nx 74-36..
Only the government would have a total of 110%!

[yhea, it's a typo but it struck me as funny :)]

Roak

[AquaTec]

padiscubapro

you raise some good points, I remember back in the 80's when PADI said you do not dive deeper than 130 feet, if you do you will get dcs or worse the rapture of the deep will just swallow you up and you may never return.

We now believe the same thing about Po2 of 1.6
just like PADI we are taught by technical diving agencies that you are sure to die if you excede this limit.

I support exploration and the questioning of what is believed to be safe. yes some will die in this exploration but we must explore and push the limits of what we know today so we can discover what we will know tomorrow

[Big-t-2538]

I'm just looking in the direction of taking tech courses. I am trying to gain as much knowledge as I can before I do anything. What I said before was based on what I had learned in my recreational Nitrox class. It was a good class, and I feel like I took a lot away from it. Diving, much like engineering, is an ongoing learning process. I just hope to learn more.

[SM Diver]

Hey, Uncle Pug, why don't you let up a bi! Why so many posts laced with sarcasim? Yeah, everyone knows you're knowledgeable, but if you don't want to share that knowledge with Dan, either because he is a spearfisherman or you don't like his prior posts, why lay in to him?

Having said that, Shooter Dan is not only an outstanding spearfisherman, but an excellent diver, as well. I have hunted with him several times.

Hey, Dan. Chris was talking to me about taking that advanced nitrox course with you guys in December. Can't do it. I'm starting a cave diving course next month. See you this Friday at the Captain's meeting for the Southern Open Derby.

[SM Diver]

AquaTec once bubbled...
Well I think you guys ran him off
Yeah, I'm sure Dan was real intimidated.

[100days-a-year]

!!!DANGER DO NOT TRY THIS AT HOME.get credible instruction before trying any of the following.!!!West Coast spearfishermens try www.mobilescuba.com for info and classes.Very few folks on this board are experienced in this type of diving so thier input while generally helpful is not always applicable.This board is very polite and well mannered if you are......usually.The only way to do this type of diving realistically is with 1 of 3 methods.1.Methodically check your BTs,SIs+depths and carry a palm or laptop to cut custom tables.2.Dive within a conventional "diveplan".Planned depth and times with pre-cut tables and back-ups.3.Get a multi-gas computer and dive it conservatively.1 and 2 suck for a spearfisherman.#3 is iffy too,but looks the best to me based on the already hi task loading involved.We currently use method 2 but use longer BTs and limit dives to 3-4 per day .OTOH commercial spearfishermen here just dive thier liberalest computer 6-8 times a day and max out PO2 by either lying to the computer or varying thier depth enough to keep from being locked out.PM me for more.

[DNAXdiver]

Since we are talking oxtox what kind of redundancy do you have in mind that will do any good other than another diver????



AquaTec once bubbled...
well i will thow in a couple of thoughts

Also I know that when I used to hunt it was always solo so if you are doing the same then buddy dependency is not an opption. just make sure you have some redundency.

[SM Diver]

AquaTec once bubbled...
Also I know that when I used to hunt it was always solo so if you are doing the same then buddy dependency is not an opption. just make sure you have some redundency
That is an interesting point, and one that I have given considerable thought to. I have just switched to doubles, with manifold and iso, which also means a different bc (trying the Zeagle Tech with optional plate, first. The Zeagle factory is twenty minutes from my house, so I can get some customization).

You should see the looks I am getting from my buddies when I tell them I am going to doubles for spearfishing. While not every hazard of solo diving can be elminated, I think doubles gives at least an extra measure of safety with the ability to shut down malfunctioning first or second stages, and isolate tanks if necessary.

I am starting a cave diving course for the sole purpose of gaining total comfort with my new gear.

[Uncle Pug]

tampascott once bubbled...
why lay in to him?


Open Derby.
Sport.

He just swam in outta nowhere reeking of aggression so I popped him.

(Later learn he is a friend of yours and has a thing for Genesis ) :D


Actually... the advise I gave him was excellent, concise and spot on... just not on a silver plater, served with garnish and a smile. ;)

[SM Diver]

Well now that Shooter Dan has been officially "Pugged" for the first time, he can settle in and feel at home. :D

[MadReefer]

Sport....he he he he

I agree he was a bit abrasive. Seemed to have "been there, done that" but wanted to know how. I kinda "lurked" the board for a while to get a feel of the tone and 'snap" of the peeps.

JMTCW
Mad:D

[AquaTec]

DNAXdiver once bubbled...
Since we are talking oxtox what kind of redundancy do you have in mind that will do any good other than another diver????


I had already given my advice on the prevention of a tox hit.

I was reffering to the fact that he probably dove alone as i did when I hunted. so some redundency in air supply etc would be a good thing, even a little pony bottle, as much as i don't use them anymore, they do have their place.

A buddy will probably not help you if you get cns O2 hit, convultions come on without warrning and you will inhale water, stopping your ability to transfer O2 through the aviolies

A buddy will have a less than 1% chance of being effective. and he is probably ate the cns % as you ..so he is next

Your only action is to antiapate a hit and use a full face mask, when your cns % is peaking like at your 20 foot stop.

Everything else is preventative

[padiscubapro]

roakey once bubbled...

Only the government would have a total of 110%!

[yhea, it's a typo but it struck me as funny :)]

Roak

oooops...

Didn't notice the typo....

But your right, what a coincidence the typo involved the government.. They always seem to invent new types of math..

[Shooter Dan]

There's some great reads here and I look forward to reading all of your replies. Thanks for the Non Garnished approach. I appreciate everyone taking the time to pass on your knowledge.

Well, I hope I passed the audition! I can tell there are some good people on this board and I hope to be an addition in the future.

Shoot Straight and Dive Safe!

[Uncle Pug]

Shooter Dan once bubbled...
Well, I hope I passed the audition! I can tell there are some good people on this board and I hope to be an addition in the future.
You did... there are... you will.

[Jarhead]

Uncle Pug once bubbled...

You did... there are... you will.

Rather long-winded today, eh?