Which Reg to start the Dive Using?

[Subcooled]

Oh, sorry, I meant 40bar/600psi.
1/12th and then 1/6th is actually 300psi - 600psi - 600psi ...

This is only twice as often as some other people do it. Frequent regulator switching is recommended in near freezing waters.

A minor detail: My regulator switching schedule is not accurately synchronized to thirds because my turnaround pressure is something like 2/3 + 200 psi due to rounding: I will round the pressure down to something easily divisible to avoid division errors. Then I divide that by three and subtract the result from the unrounded value. As a result I will use slightly less than 1/3 on entry. It's easier to calculate and it's slightly conservative. Win-win. Sometimes I dive quarters instead of thirds. So, having a regulator switching schedule that is independent of thirds works nicely for me. Further, I don't need to remember switching pressures or the fill pressures, I just look at delta P.

Using a longhose at the beginning of the dive is good practice. If your dive buddy serviced both regulators (or cylinders) at the same time, and something went wrong (I have seen this happen) then both/all regulators could fail at certain depth. Contaminated gas (carbon monoxide) could also lead to an out of gas situation that starts during descent.

 

[karstdvr]

I generally make sure to breathe 100-200 psig off each reg to start with then,and then I let the configuration of the cave I am in decide what will be the best means of swapping regs. Since I dive sidemount caves,air sharing is not part of the plan,because each person has an independent gas plan; also I use two short hoses because I want nothing around my neck.

 

[ajtoady]

I run a longish hose, 5' , on each tank. Nothing around my neck though. Hoses store nicely on the tanks with bungees and are routed directly across my chest. I am not a cave or confined area diver so 5' is more than enough. As for which tank to start with, always the right tank for me. Left is on a bungee around the neck and it's my thought that by doing things in the same routine or sequence, it becomes more normal place. I Also do a complete reg check and swap at 25-35' at the beginning to assure all regs, gauges, valves, and inflators are in working order. But you know what, this is something you need to figure out, and be comfortable with. So have fun and dive safe!

 

[CamG]

I always pre-breath each reg R/L.
Do a S drill to ensure no hose traps, bubble check, gas match T/P.
Then I start the dive on my short bungeed L.
I purposely do this to leave my long hose R , 200 - 300 PSI greater incase my buddy needs it.

On the exit I balance the tanks once I get to 500' to exit in a cave.
OW I keep them close to the same plan till on exit , deco.
Just my practice and not what seems to be the consensus so take it with a grain of salt.

CamG