Jack Hammer
Contributor
He who questions training only trains himself at asking questions
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You are misunderstanding what I am saying @PhatD1ver.
Any rigid system can 'break', not having one cannot.
For example: any routine you might have developed is broken on decent as soon as you add a third tank.
There is no real reason why you should not switch regs several times in any interval you might set, but a lot of reasons to not be able to do a comfortable switch at any one certain point in time (forcing you to postpone it).
Not using rigid intervals reduces the need for exact calculation and the resulting taskload.
You must have giant tanks if that is trueIf I am off by 400, I tilt. My tanks, combined, weigh as much as me and my gear.
What I am proposing is not the 'easy way' PhatD1ver.But thinking that you can just 'wing it' is not gas management, ...
Not a problem if your plan is 'switch after he has distracted you and before every planned waypoint of the dive'.And will also create scenarios to distract you from making a switch or checking your time and also tehpressure according to the plan.
A third tank breaks the normal routine....with a dive plan that would require a 'third tank'.
Okay, maybe I exaggerated a little, but my dive buddies notice it. LP85s or HP100s.You must have giant tanks if that is true
To be off by 400psi with that tank size would be close to impossible with frequent switches.
I would perhaps do 6 switches (with my 19liters I switch more than once every 10 or 15 bar, less than half a pound of maximum weight change) for every switch you do, so I could never be off by more than a few hundred grams of gas weight.
what do you do when you get down to a third in each tank? do you keep going on alternate tanks or keep ⅓ aside for OOA emergency and stay on one tank ?This is important!
Reading this thread, it's less about gas management and mostly about gas balancing. I'm with Bob. What ever you decide on, make it consistent.
I like to keep tanks within 300 PSI. I breathe one tank down 300 psi or to when it's a multiple of 300 and then start the back and forth. Say my tanks are at 3500. The left gets hit first down to 3300, then I breathe the right to 3000, the left then down to 2700 and so on. I use two Hollis DG03 with transmitters. Each has the transmitter on that side as the primary gas and the one on the other side as the second gas. I use rechargeable batteries in the transmitters and they get changed out every other dive. The only errors that I've encountered have been human induced.
Since I've turned the dive by then, and I rarely go all the way to thirds, I keep switching. Don't put all your eggs in one basket!what do you do when you get down to a third in each tank? do you keep going on alternate tanks or keep ⅓ aside for OOA emergency and stay on one tank ?
what do you do when you get down to a third in each tank? do you keep going on alternate tanks or keep ⅓ aside for OOA emergency and stay on one tank ?
Good question. If I am down to a third in each tank, I am already on my ascent (perhaps I am at the tie-in on the wreck we are diving, beginning the ascent, but usually I am already on the way up). And, at that point, on a recreational dive, I do not continue switching. I breath from one cylinder until I am on the surface.what do you do when you get down to a third in each tank? do you keep going on alternate tanks or keep ⅓ aside for OOA emergency and stay on one tank ?
"he's effectively solo diving at that point,'--other than buddy sharing you mean? youve still got a third left its just spread across 2 cylinders? the was a post I read (cant remember where) about what constitutes an overhead e.g. a wreck with windows 4m away is different to a cave 100m in- i suppose its a situational decisionIn open water, thirds isn't a requisite gas reserve since your bailout strategy is to go up, and the last thing you'd want to do is run one tank beyond the point of a useful bailout since that means you've lost your redundancy. If I'm inside a cave or other overhead then I shouldn't get below thirds, and if I have then I've screwed up big-time. But I'm still going to alternate, for the same reason. But I'm going to make sure my buddy knows I'm below thirds, and that he's effectively solo diving at that point, since he can't count on me for reserve gas. Redundancy is the priority at this point ... but recognize that this is a broken dive, and shouldn't be allowed to happen ...
... Bob (Grateful Diver)