85m air dive

[Sas]

You basically gave all the reasons anyone would want to go into a cave

There are more reasons than that though For example, some people do it for ego reasons, or perhaps they live near caves...

which pretty much everyone is aware of anyway.

Not really, I often get asked why I like caves by divers and non-divers... Unless people are doing the type of diving, they might not understand the reasons *why* someone would do those dives.

There needs to be a reason for the why And if it is obvious to you, fair enough, but it was not obvious to me why someone would like to dive to 85m on air.

 

[Kern]

Well in that case I have a question.



Why so little O2 deco? What do you have against it? That's really going to limit your dive times. Have you considered using air breaks?

Ian, this dive as is, is already around 300% CNS. Increasing the bottom time, increasing the EAN50 & O₂ deco time would push the CNS into rather extreme territory.

Doubling the BT to 16 minutes would have the CNS at over 700%.

 

[ianr33]

Yeah I understand that,was wondering if the aversion to O2 deco was a general thing or just this type of profile.

Personally I wouldn't want to do a dive where I was worrying about CNS% O2 as I switched to O2 .

Yet another reason to keep bottom pO2s sane.

 

[Cave Diver]

Ian, this dive as is, is already around 300% CNS. Increasing the bottom time, increasing the EAN50 & O₂ deco time would push the CNS into rather extreme territory.

Doubling the BT to 16 minutes would have the CNS at over 700%.

So, doesn't that seem like a good argument for using a different gas at depth to lower the O2 percentage?

Adding just 4 minutes to bottom time (say in the event of a problem) increased the deco to almost 1.5 the times. That additional bottom exposure jumps the CNS% up considerably as well.

Dropping the O2 content of the bottom mix substantially cuts the CNS%. If CNS is such a concern that you don't want to spend additional time on 100% near the surface, why not just fix the problem at the source?

 

[Cave Diver]

Yeah I understand that,was wondering if the aversion to O2 deco was a general thing or just this type of profile.

Personally I wouldn't want to do a dive where I was worrying about CNS% O2 as I switched to O2 .

Yet another reason to keep bottom pO2s sane.

Damn. You beat me!

 

[rjack321]

Dropping the O2 content of the bottom mix substantially cuts the CNS%. If CNS is such a concern that you don't want to spend additional time on 100% near the surface, why not just fix the problem at the source?

Silly boy, that requires actual technical/deco training, knowledge, helium, and money. Which is why this dive is being "discussed" in the "advanced" forum instead of amongst legitimate peers in the technical or tek to tek subforums.

 

[Kern]

So, doesn't that seem like a good argument for using a different gas at depth to lower the O2 percentage?

Adding just 4 minutes to bottom time (say in the event of a problem) increased the deco to almost 1.5 the times. That additional bottom exposure jumps the CNS% up considerably as well.

Dropping the O2 content of the bottom mix substantially cuts the CNS%. If CNS is such a concern that you don't want to spend additional time on 100% near the surface, why not just fix the problem at the source?

No mate, it would never occur to me to plan an 85mt dive with some worthwhile bottom time & some contingency planning. Or that I could use a suite of gasses to do so & keep my CNS below 50%. :shocked2:

 

[Cave Diver]

No mate, it would never occur to me to plan an 85mt dive with some worthwhile bottom time & some contingency planning. Or that I could use a suite of gasses to do so & keep my CNS below 50%. :shocked2:

That was a general question, not directed to you specifically. I just used your quote for illustrative purposes. Apologies if that wasn't clear.

Silly boy, that requires actual technical/deco training, knowledge, helium, and money. Which is why this dive is being "discussed" in the "advanced" forum instead of amongst legitimate peers in the technical or tek to tek subforums.

Ooops. My bad...

 

[Kern]

That was a general question, not directed to you specifically. I just used your quote for illustrative purposes. Apologies if that wasn't clear.

No worries here. I was just using Ian & your comments to inject some numbers & thoughts into the discussion too.

 

[Tortuga68]

Why so little O2 deco? What do you have against it? That's really going to limit your dive times. Have you considered using air breaks?

Kern already covered it

Silly boy, that requires actual technical/deco training, knowledge, helium, and money. Which is why this dive is being "discussed" in the "advanced" forum instead of amongst legitimate peers in the technical or tek to tek subforums.

Thanks for condescending to post in my humble thread, your input is as constructive as ever