Wanna stay down longgerrr

[Blackcrusader]

You are asking a different question here than you did before, so you will get a different answer.
Before your issue was CNS buildup, which is NOT really possible given the dives you describe.
If the ONLY issue is getting to 45m "safely" using twin 63s, IF YOU USE AIR the only question is your breathing rate.
Do not try and emulate Black Crusader's dives; he has strange physiology and uses very little gas.
What is YOUR breathing rate? .

You gave me a good laugh there on your comment about me. I got a strange magic for diving and some think I am a mutant.

However I already did ask this chap about his SAC / RMV. As noted by our other deep air diver he should learn to deco on air, and he should know his sac rate. The reason agencies do not want divers with a single tank doing deep ( or not so deep ) deco dives is that their air consumption would not allow them to complete deco obligation and have enough reserve air for an emergency. So yes apart from some gear failure ( which I have never had in 35 years of diving ) there is a reason that people should have a twin tank setup or bring a second tank with them.

Instead of being concerned about CNS the issue is he wants to have deeper MOD first for a longer period of time. This is fine on air if doing planned deco dives with knowing your SAC rate. This would also entail your dive buddy ( if not diving solo ) to have the deco training as well.

 

[huwporter]

Generally to your main question. you can not extend NDL and MOD at the same time. These are two apposing forces.

Actually there are at least a couple of options:

Firstly, you could become a different species - apparently Guinea Pigs can happily do profiles that would result in unpleasant consequences for humans.

Second option for going deeper and longer without incurring deco is to buy a submarine.

But yeah, if you are going to insist on doing your dives by SCUBA diving as a human, then you are stuck with human physiology, which means you have human physiology limitations.

 

[Blackcrusader]

Basic issue. My dives are currently usually limited to my NDLs or sometimes CNS%.>

CNS is not your issue. Only MOD and NDL. You could stick with air and do DECO courses for deep dives like 120 feet. Maybe later you could consider something else. Just my humble opinion as I have no technical dive training. Just Deco trained on air and nitrox. Back in the 1980's Nitrox wasn't even around. If you are only doing dives to 70 - 80 feet then air deco will be fine or just nitrox which will extend your NDL but limit your MOD

Question is how deep are you planning on diving and for what time? To NDL? To planned deco?

 

[rx7diver]

I see that on this point the knowledge advanced significantly beyond what I was taught in 1975-77. ... And it was considered safe to dive for a couple hours at ppO2=2bar, which is far beyond current recommendations.

@Angelo Farina,

My first EAN certification training was in 1993. It was an IANTD class that used Dick Rutkowski's "Enriched Air Nitrox" manual/workbook. At that time the maximum exposure for non-technical, non-decompression, recreational dives was considered 1.6 ATA. For technical dives, max exposure for the "working" part of a dive was considered 1.5 ATA. (We were preparing for OC air dives, cold and deep, in the Great Lakes, using oxygen deco.)

When I took my "IANTD Advanced Deep Air" (air dives to a bit deeper than 200 ffw, with EAN36 and oxygen as deco gases) certification training in 1995, max exposure for the "working" part of technical dives was recommended to stay between 1.4 ATA and 1.5 ATA for the working portion of the dives--primarily to leave enough oxygen exposure room for decompression.

(I don't recall what oxygen exposure limits were being taught when I did my TDI Extended Range and Technical Nitrox training in 1998.)

I read SB comments now where people are routinely limiting their oxygen exposure on open-circuit dives to 1.4 ATA, max, even for recreational dives.

I think it's safe to conclude that things have become more conservative over time with respect to oxygen exposure.

rx7diver

 

[tursiops]

I think it's safe to conclude that things have become more conservative over time with respect to oxygen exposure.

It is also possible to conclude that as more data has come in and more understanding has occurred, the limits have been revised better to match reality, not to be more conservative.

 

[Blackcrusader]

It is also possible to conclude that as more data has come in and more understanding has occurred, the limits have been revised better to match reality, not to be more conservative.

Well these are the default settings in the Perdix....

 

[rx7diver]

Well these are the default settings in the Perdix....

View attachment 631519

View attachment 631518

Oh, my! Maybe this explains things! (I never dove, I don't dive, with a DC--except to record the dive.)

rx7diver

 

[Blackcrusader]

Oh, my! Maybe this explains things! (I never dove, I don't dive, with a DC--except to record the dive.) rx7diver

I made an error I changed my setting to SALT as I do ocean diving. The preset is the standard European setting which is sort of halfway between fresh water and salt.

Any way everyone should learn what their dive computer can tell them regardless of diving recreational within NDL, DECO air, nitrox and what ever else they have. I'm a recreational diver trained in DECO air dives. So not a technical diver. However over the last few years I have studied about GF factors, CNS, PO2 and other things I never had in training before.

 

[Blackcrusader]

What Ive never heard of is the computer telling you this, and giving high CNS values based on it. Is it possible that your computer calculates and gives you "OTU's"?

Oxygen Toxicity Units are usually a system used for technical divers yes? So why would an EANX dive be setup to have OTU shown on a dive computer?

He is claiming he is getting 70% CNS which is near the max limit CNS of 80% yes? As he is not diving on CCR and using O2 at 6m depth how can he have such high CNS or OTU readings if he is diving and not exceeding NDL limits on air or nitrox?

 

[Blackcrusader]

Basic issue. My dives are currently usually limited to my NDLs or sometimes CNS%.

Would you please post a picture of your computers dive log and graph as I have done from my Perdix. Then we can all be clear what settings your dive computer is on and see the gas used, depth, time, PO2 CNS details as you can see in my dive log. Perhaps even your SAC rate if you have entered the dive tank size and pressure details into something like divinglog.com