Two Deco Bottles

[Rainer]

For those that are T2, what's your "inflection point" for deciding to take two deco bottles versus one? I know some guys are using 50% and O2 for 150-160' dives, where I'd only bring 50% (limit of my T1 training). I assume RD stays the same regardless (for these T1 depths), so it wouldn't seem to be for further accelerating the deco (i.e. getting out of the water faster). Just for cleaner deco? At what depth or for how much deco do you want that second bottle around?

When do you decide to add the O2 and why?

 

[rjack321]

You don't accelerate your deco more, ie. a 20min dive at 160ft still requires 12mins total between the 20ft and 10ft stops. While O2 is giving you a bit of a boost, 12mins isn't very long and O2 is not re-accelerating your deco so much than you can 'get away with' 6mins. Ditto a 40min dive to 150ft requires 20 mins from 70 to 30 and 20 mins at 20 and 10ft.

I carry O2 when:
My deco times exceeds 25mins, to provide coverage for a lost gas.

I am quite distant from EMS aid and having a bit cleaner deco is prudent, I could do this by adding 50% time but then I run into volume issues on an AL40, its easier for me to bring 2 deco gases. For these dives I am bumping into or beyond Tech1 maximum deco exposure limits anyway, so this 2nd reason is a bit redundant with the first. Although if we were diving together in Northern BC or someplace like that I would still bring O2 even if we chose to stick to ~20mins and 1 deco gas. Mostly cause I am "sensitive" after surgery on a cervical disk a few years ago.

That's my personal gray wafflely zone for ya.

 

[MonkSeal]

T2 dive is not only determined by depth it's time that also plays the role. Usually we take 50% and O2 when exposure requires it. However, we take sometimes two deco gasses for having little bit cleaner deco and better redundancy in gas management.