My AN/DP/Helitrox course

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I know. It's just that posting along with a course invites advice, and some of it may conflict with what your instructor or agency teaches. I am pleasantly surprised at how little unsolicited advice you have gotten here so far, not to mention encouragement. Personally--and you didn't ask for my advice (ha ha)--I prefer to listen to one voice at a time.

I’ve seen too much stuff passed off as “standards” when it’s nothing more than personal preference. That is why I asked for a reference.
 
I’ve seen too much stuff passed off as “standards” when it’s nothing more than personal preference. That is why I asked for a reference.

It seems to me that when one gets into the tech realm, there's a hazy line between standards and personal preferences. Some agencies still teach deep stops. Experienced divers' personal preferences are often grounded in literature they have read and their own experiences. Your instructor's and Richard's "preferences" versus TDI's "standards" .... It's all grounded in more than whim and all worth taking in ... at some point.
 
Have you tried some of the FL instructors? Not that far of a drive for you and you could do it in the "off" season for NC

Those where Fl instructors...
Helitrox class goes to 150ft.

@rjack321

So you are advocating for mixes not containing over 21% O2 (such as 21/20, for example) or only standard mixes (21/35)? Your post wasn’t clear on that point.

Regardless of the O2%, there is no reason for me to pay a great deal extra for helium just to get a standard mix. Maybe it’s banked in your area. It’s not banked here.

A few posts ago you were talking about how narced you were at 130', but now your are saying you don't need that much helium?

I’ve seen too much stuff passed off as “standards” when it’s nothing more than personal preference. That is why I asked for a reference.

Have you read Gareth Locks book, "Human Factors"?
 
A few posts ago you were talking about how narced you were at 130', but now your are saying you don't need that much helium?

That helium stuff is $$$$, an END of 119ft is good enough! (joking). NAUI taught 25/17 for a few years as a standard mix - Bruce Weinke (RIP - he died this past weekend) was an advocate for this mix as the 17% was light enough to behave similar to nitrox. It never really caught on. In the cusp years between AG leaving GUE and starting UTD he taught for NAUI and bent the rules on 25/17 to make it 25/25 but never at 150ft. 25/25 is 100-130ft gas under that paradigm.

I have done Great Lakes dives with ENDs in the 120s. It might be cold but the vis is pretty good and there's plenty of ambient light down into the 250+ft range so its not hideously narc-ing to me.
 
I have a lecture section in my AD/DP class about the use of technology. The primary tech that I advocate for isn't new computers, or scooters or heated vests, but using the internet for information. Real information, not necessarily youtube, Facebook or even Scubaboard. In-person forums like TekDiveUSA are phenomenal resources if you can go, DAN has a whole educational library and the Rubicon Foundation has tons of peer reviewed scientific journals, as does Google Scholar.

I mention this because at the technical diving level, you can no longer depend on the certification agencies to keep up with current practices. They just don't have the time to update their materials as often as is needed. A working pO2 of 1.4 is a prime example of that. The generally accepted trend is using lower pO2 across the board, particularly if you are doing any kind of work. When I started diving 2.0 was the accepted limit. Then it was 1.6. Now it is 1.4 for the bottom and 1.6 for deco. Common practice with CCRs is 1.3 to 1.2 for working and up to 1.6 for deco, but possibly less if you are on a long dive or doing multiple days of high PO2 diving. Some deep divers are using 1.0 for their bottom mix. Sure it'll take longer to get out of the water, but it's better than toxing or going blind.

-Chris
 
I have done Great Lakes dives with ENDs in the 120s. It might be cold but the vis is pretty good and there's plenty of ambient light down into the 250+ft range so its not hideously narc-ing to me.


Question for you: when you say that ambient light makes it less narc-ing, is it only about being aware that you are narced or are you really less narced with more light ?
 
Are YOU going to cough up the cash for the extra helium? It’s $3/cft. Let me know what email of yours I can use for the PayPal funds request.
Depending on whether they boost the helium and how they charge you might find having 21/35 or thereabouts for the first dive and then an air top costs the same as two weak fills.

35% of 160 cu ft is about 55 cf or 165 USD per fill. You will maybe save $80 by using much weaker mixes. You have spent months, bought a load of kit, travelled all over the place etc. Say you have four days of deco diving (actually I suspect you will only have two) then you will be saving maybe $300. More likely you’d be doing two deep dives, have boosted gas and pay 165 for the first fill and 90 for the second vs 85 for the first and 50 for the second so $255 vs $135. Is that so much in this context?

I got quite noticeably narked at 35m recently when I made a poor decision about which dil to take that day, thinking it would be a waste of 18/45. I had to sort out a thing and it took longer than it should have.

You may find you personally get more or less narked. I suggest trying it both ways.

What are you doing about suit gas?
 
Question for you: when you say that ambient light makes it less narc-ing, is it only about being aware that you are narced or are you really less narced with more light ?
I would say that the "closed in feeling of doom" is much more pronounced at 100ft in 5ft vis with zero ambient light
vs
Being at 120ft END in 50ft vis plus copious ambient light. Roughly the same water temp and workload for both.

I don't know of any actual empirical evidence to say I was less narced at 120ft END with ambient light though. I am pretty sure I am more functional with ambient light in general. Its WAY easier to keep track of buddies, navigate, see your own dang pocket contents etc etc.

But actually solve a unique or novel problem? I would guess its a wash. 20ft difference in END is barely measurable dive to dive or diver to diver.
 
I have a lecture section in my AD/DP class about the use of technology. The primary tech that I advocate for isn't new computers, or scooters or heated vests, but using the internet for information. Real information, not necessarily youtube, Facebook or even Scubaboard. In-person forums like TekDiveUSA are phenomenal resources if you can go, DAN has a whole educational library and the Rubicon Foundation has tons of peer reviewed scientific journals, as does Google Scholar.

I mention this because at the technical diving level, you can no longer depend on the certification agencies to keep up with current practices. They just don't have the time to update their materials as often as is needed. A working pO2 of 1.4 is a prime example of that. The generally accepted trend is using lower pO2 across the board, particularly if you are doing any kind of work. When I started diving 2.0 was the accepted limit. Then it was 1.6. Now it is 1.4 for the bottom and 1.6 for deco. Common practice with CCRs is 1.3 to 1.2 for working and up to 1.6 for deco, but possibly less if you are on a long dive or doing multiple days of high PO2 diving. Some deep divers are using 1.0 for their bottom mix. Sure it'll take longer to get out of the water, but it's better than toxing or going blind.

-Chris
I would say that the "closed in feeling of doom" is much more pronounced at 100ft in 5ft vis with zero ambient light
vs
Being at 120ft END in 50ft vis plus copious ambient light. Roughly the same water temp and workload for both.

I don't know of any actual empirical evidence to say I was less narced at 120ft END with ambient light though. I am pretty sure I am more functional with ambient light in general. Its WAY easier to keep track of buddies, navigate, see your own dang pocket contents etc etc.

But actually solve a unique or novel problem? I would guess its a wash. 20ft difference in END is barely measurable dive to dive or diver to diver.
I would say that the "closed in feeling of doom" is much more pronounced at 100ft in 5ft vis with zero ambient light
vs
Being at 120ft END in 50ft vis plus copious ambient light. Roughly the same water temp and workload for both.

I don't know of any actual empirical evidence to say I was less narced at 120ft END with ambient light though. I am pretty sure I am more functional with ambient light in general. Its WAY easier to keep track of buddies, navigate, see your own dang pocket contents etc etc.

But actually solve a unique or novel problem? I would guess its a wash. 20ft difference in END is barely measurable dive to dive or diver to diver.
I have a lecture section in my AD/DP class about the use of technology. The primary tech that I advocate for isn't new computers, or scooters or heated vests, but using the internet for information. Real information, not necessarily youtube, Facebook or even Scubaboard. In-person forums like TekDiveUSA are phenomenal resources if you can go, DAN has a whole educational library and the Rubicon Foundation has tons of peer reviewed scientific journals, as does Google Scholar.

I mention this because at the technical diving level, you can no longer depend on the certification agencies to keep up with current practices. They just don't have the time to update their materials as often as is needed. A working pO2 of 1.4 is a prime example of that. The generally accepted trend is using lower pO2 across the board, particularly if you are doing any kind of work. When I started diving 2.0 was the accepted limit. Then it was 1.6. Now it is 1.4 for the bottom and 1.6 for deco. Common practice with CCRs is 1.3 to 1.2 for working and up to 1.6 for deco, but possibly less if you are on a long dive or doing multiple days of high PO2 diving. Some deep divers are using 1.0 for their bottom mix. Sure it'll take longer to get out of the water, but it's better than toxing or going blind.

-Chris

Try out DiveSafe, it’s a very simple to use mobile app that can help estimate in a very visual way trimix , end, gas densities and such.... it has also a very advanced gas blending functionality.

It costs a bit, so try out the free recreational version first, DiveSafe Nitrox.

Using some technology to choose a good gas is not a bad idea
 
http://cavediveflorida.com/Rum_House.htm

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