How much Deco

scubanimal

Left column I use imperial settings, 1min stop, & ATM
I click the 20ft Deep box, with stop size set at 10, 15, 20 (CCR), I set my max 100% O2 at 20ft, deco mixes at 1.4 across the board, RMV (use your values, aka SAC rate)
I click extended stops with 2 in each box, and I click the All deco mix changes box. I generally set my Conservatism to +5 (hey its my choice) and use the VPM-B model. Decent rates are your choice, as a relatively new CCR diver you may want to keep it a bit slow, my ascent rates are set for HE mixes and I just do that regardless of the actual mix.

I am very conservative obviously. But this is working for me.

Tino de Rijk

There is nothing psychological about convulsions. they are a proven very real thing with a very real physical/chemical foundation.
It is just that the susceptibilty various from person to person, AND (which is IMHO much more important) from day to day, and from situation to situation, with factors of importance like dehydration, CO2, fatigue, stress, cold, etc.

The risk increases non-linear as the PO2 rises. It's really that simply. That doesn't mean that at 1.4 you are 100% safe, and that at 1.6 you are 100% at risk of getting one of the nasty CNS effects (convulsion not being the only one) soon. It just means that your risk is significantly bigger at 1.6.

and my simple point is: why take the risk anyway? The advantage on a 'breather between 1.3 and 1.6 for deco is quite limited, so why enter the "convulsion gambling casino"...?

comparisons with dry PO2 exposure (i.e. in a tank) have no meaning: totally different issue. I'm too lazy to write that out in full, but there is quite a lot of literature on that. A tank is a.o. good temperature, no CO2 at all, no work at all, limited stress (well.... maybe a bit, because you were bent....), being hydrated by either drip or drink, etc.
And they also don't care if you get a convulsion, since you are "safe" in the tank: you won't drown, just maybe bite your tongue, which to the medical guys is quite acceptable (maybe not to your wife....).

There really is tons of literature on this subject.

ciao,

Tino.