Thanks DIR Atlanta!

[rjack321]

You used 30/30 at Peacock? :shocked2:

I suppose we could have done it on a stage of 32% but that's not what we had at the time.

The weird thing to me about the fill situation was that we were having to transfill backgas into the used stages because Edd's booster is limited to about 3000 psi. So we would take 3000psi of remaining backgas and drain it a bit into the stages leaving 2400 in backgas and 1400 in stages. That way he could refill both to "full" - 3800 and 3100 respectively.

My gauge reads a little high (~75psi it seems, its not a 100% linear error) but having 3900 in double 104s was pretty swell.

 

[rjack321]

You're being much too kind.

Rjack and I were hovering at our 20 foot stop in Peacock, when the aforementioned diver came crawling up the slope between us to retrieve his O2 bottle (which as rjack pointed out, had been stowed at 14 feet). "Crawling" is not an exaggeration - he was literally on all fours for most of the way. He grabbed the bottle and retreated down the slope, but instead of clipping it off for the deco, he was carrying it the whole time in both hands, in front of him like a sack of flour.

That's about all I could see since they were mostly behind me, and I wasn't paying that much attention anyway because that kind of stuff is pretty common at most of the N Fl caves. The look on rjack's face was priceless however - I almost spit my reg out from laughing so hard.

The nearly full double bladder bungied wing just got me

 

[DIR-Atlanta]

I suppose we could have done it on a stage of 32% but that's not what we had at the time.

I got the initial fills at Amigos in Ft White, where it's usually just easier and quicker to fill everything with the same gas.

The weird thing to me about the fill situation was that we were having to transfill backgas into the used stages because Edd's booster is limited to about 3000 psi. So we would take 3000psi of remaining backgas and drain it a bit into the stages leaving 2400 in backgas and 1400 in stages.

That's an effect of not using that much back gas.

I don't think Edd does that much in the way of trimix fills, so he is not really set up for "high volume". He does a great job though and is not that expensive on gas. After his power came back on Friday night, he stayed up until 1:30 AM filling our tanks for the next day's dives, which I thought was really nice of him.

I can still remember the "dark days" when there was no place within 50 miles of Marianna to get so much as an air fill, so I really appreciate having Edd there. He's a real nice guy who provides a valuable service, and is very conveniently located. I hope he stays in business a long time.

 

[SparticleBrane]

I am too cheap for 30/30. 32% for me...

 

[DA Aquamaster]

I see Sparticlebrane brought it up but the 30/30 struck me as an odd choice in a cave with a dive profile that would have a lot of sawtooths and where the END of 32% would never exceed 70' anyway and would be half that for most of the dive. The touchier nature of He with regard to ascent and deco obligations is just an added liability as a reduced END is not requried.

Also, you imply that you nearly always dive stages. Is there an advantage in aways diving stages and never breathing off the back gas? Given the extra drag as well as the extra care needed to prevent silting and cave damage, particularly in some of the tighter tunnels and low duck unders that could be found in the system if you decide to go off the main line, why would you take them if they add nothing to the dive that back gas would not provide - especially on a shallow dive like the Pothole and Peanut tunnels?

I also don't see the upside of carrying stages in a high flow system if the planned penetration does not require them. It's a lot of trouble to go to just to avoid a backgas fill.

Just curious what I am missing here as on the surface it seems to be a lot less than optimum, especially from a DIR perspective.

 

[rjack321]

For me 30/30 and 32% are both -20% EAD gases. We had 30/30 I used it, no big deal. I do the same ascents (1s from 50% of depth). Below 50% of depth I ascend at 30ft/min (since these were barely deco dives). We never even came close to that ascent rate on even the spikiest profile which I think was the P-O traverse.

Most of our dives were actually 1 stage plus about 1/5ths of remaining backgas. I think I used a stage plus about 500 from the 104s for each Hole in the Wall dive. That was how JB was supposed to be as well (1/2 plus 200 on each stage plus 500 off backgas), however Atlanta got tired on me and we exited from lack of mojo and getting close to a max penetration time we agreed to.

We could have done JB dive on 1 stage and backgas, it was a mid-dive change of plan. We could not have done that dive on backgas alone (nor could we have done P-O + the peanut tunnel, nor 1,100ft up and downstream Hole-in-wall on backgas alone).

 

[rjack321]

I am too cheap for 30/30. 32% for me...

Eh, I would have done Peacock on 32% no biggie. And probably hole-in-the-wall too. No way would I try a double stage swim dive into JB with 32%. Compared to hotel, food and airfare, He costs were trivial (it was about $140 for my fills, including O2). A bit less than my costs for one "big" tech dive up here - and I have my own boat and compressor.