ICD and gas swaps

[PfcAJ]

Never

Which part? Never tried helium or don’t think you’ve experienced narcosis?

Everyone thinks “they’re good” till they dive with some helium.

Personally, I wouldn’t sign up for a 300ft dive with anything approaching a 100ft END.

All these complications of special “best” gases, wacky ENDs and gas densities, and god knows how you’ll end up marking your bottles because every dive is best mix just to avoid the extreme remote possibility of ICD is silly. Thousands of dives have been done using the gas combos I listed and some how some way there just isn’t a problem with ICD.

 

[Dr Simon Mitchell]

Yes I kwow that .... by the way I put in my software a EADD ( Equivalent Air Depth Density ) indication when choosing bottom gasses and deco gasses ( I think it's the only software with this option ).

Hello Antonio,

He will correct me if I am wrong but I think Ross also put a density warning function into Multideco after publication of Gavin Anthony's density data (which can be found here).

As for the rest of the debate, I do have to agree with AJ et al. that there is potential for substituting a higher risk of things like (take your pick) cylinder overload, mixing errors, switching errors etc to mitigate a very small risk of ICD related issues.

Simon M

 

[TheSnake]

Which part? Never tried helium or don’t think you’ve experienced narcosis?
Everyone thinks “they’re good” till they dive with some helium.

Yes I tried air, nitrox, normoxic trimix and hypoxic trimix dives.

I think this is a deadlocked discussion.
Yes, we all know that at certain depth, we all are, more or less, under narcosis.

Question is: at which point? Does this affects our reactions and compromise our choices and our security?
You have to ask your question to scientists .... If I have to rely on my personal experience,
I have never seen anyone affected by narcosis to the point to putting themselves in danger,
not knowing what he's doing, by making air dive at 30 meters / 98 feet.
( If you drink a centilitre of wine, you have a certain degree of alcohol in the blood, that's for sure,
but that represents a danger? ).

And be sure, I do not totally dispute your choice of gases, I simply say that you seem to be too much conservative ( in my opinion ).

 

[PfcAJ]

Yes I tried air, nitrox, normoxic trimix and hypoxic trimix dives.

I think this is a deadlocked discussion.
Yes, we all know that at certain depth, we all are, more or less, under narcosis.

Question is: at which point? Does this affects our reactions and compromise our choices and our security?
You have to ask your question to scientists .... If I have to rely on my personal experience,
I have never seen anyone affected by narcosis to the point to putting themselves in danger,
not knowing what he's doing, by making air dive at 30 meters / 98 feet.
( If you drink a centilitre of wine, you have a certain degree of alcohol in the blood, that's for sure,
but that represents a danger? ).

And be sure, I do not totally dispute your choice of gases, I simply say that you seem to be too much conservative ( in my opinion ).

I think generally a person on nitrox at 98ft isn’t out of line. It’s a relatively shallow depth. Plenty of time to sort out your business.

I’ve seen plenty of people fumble with stuff, make not the worlds best choices, miss navigation markers, do sloppy bottle drops, etc at depths around 100ft on nitrox.

I wouldn’t want any of that going on at around, or below 300’. Just eliminate that variable all together.

 

[TheSnake]

Hello Antonio,
He will correct me if I am wrong but I think Ross also put a density warning function into Multideco after publication of Gavin Anthony's density data (which can be found here).

OK. I did not find it but if you say that it has EADD I trust you.

As for the rest of the debate, I do have to agree with AJ et al. that there is potential for substituting a higher risk of things like (take your pick) cylinder overload, mixing errors, switching errors etc to mitigate a very small risk of ICD related issues.

On this point I do not understand your position ...
Firstly, a hypoxic trimix diver is trained for using heavy tanks configuration that's a part of his skills.
In the examples above, we've used the same number of tanks ... so switching error risks are the same .....

 

[PfcAJ]

OK. I not found it on but if you say that it has EADD I trust you.



On this point I do not understand your position ...
Firstly, a hypoxic trimix diver is trained for using heavy tanks configuration that's a part of his skills.
In the examples above, we've used the same number of tanks ... so switching error risks are the same .....

Number of tanks is not the only factor impacting potential for gas switching errors.

 

[TheSnake]

Number of tanks is not the only factor impacting potential for gas switching errors.

You mean blending errors?

 

[PfcAJ]

You mean blending errors?

Issues to contend with using “best mix” for deco gases:

Blending errors, marking errors, lack of “routine”, confusion between team members, need to cut special tables for every dive, difficulty memorizing decompression schedules and trends, perceived inflexibility if dive parameters change, probably more things I missed.

Avoid all that noise with standard gases. You *might* end up with a few mins more deco time but the pre-dive hassle and added complexity greatly outweighs that minor drawback to me.

 

[TheSnake]

Yes, maybe ...
but if you always dive using these mixes with your buddies ....

 

[PfcAJ]

Yes, maybe ...
but if you always dive using these mixes with your buddies ....

But with “best mix” it’s always something different. No continuity from day to day and dive to dive.