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Gas planning for technical dives?
My T1 class is coming up fast in the next couple of weeks and I was thinking about gas planning. Normally I calculate rock bottoms for min. deco. to the surface. Does that change when you're carrying a deco gas? Might be a stupid question but it was something I'm unsure of.
You'll cover this in class. Min gas is always to the next breathable gas source. For recreational dives, that's the surface. For staged decompression dives, that's to the next bottle. Realize, too, that min gas must also cover any decompression requirements on the way to that next bottle.
That's what had me thinking. Admittedly I really don't know anything I'm talking about here but sort of thinking out loud.Originally Posted by Rainer
I would think you should plan rock bottom to deco on back gas in the event of lost deco gas. I guess dive planning really plays into effect here as I'm assuming there'd be a big difference in time required depending upon your depth and bottom time. In this planning I'm also assuming you're planning for either losing your deco gas or your buddy losing his back gas and not both? Or would one most likely cover the other and you go with the most conservative? If you couldn't notice I'm growing impatient to start the class and get away from the snow for a little bit
You will become intimately acquainted with this topic in your Tech 1 class with Bob. Yeah, gas planning is pretty critical for Tech 1, but it is all based upon the same type of calculations you learned in Fundamentals. If you really want to prepare, I would just review the minimum gas calculations, SCR calculations, volume consumption calculations, etc. which you learned in Fundamentals. Have fun!
Ken
"Appreciate your life!"
1 major failure:
buddy loses backgas, get him up to his deco bottle
you lose your deco gas, get you up to the surface from where you'd otherwise switch
you need to reserve whichever is larger but not both
For GUE T1 dives up to ~25mins or so with 50% for deco the numbers end up being similar: 65-70cf depending on your depth, how much deep stop time you end up with, and how you share gas & reshape the deco in the event you lost your deco gas.
What he said. Basically, you are expected to cover for loss of any one gas source.
Tom
No, you plan both separately, then manage your resources based on which calls for more gas (lost bottle vs. min gas). They're often similar needs, and in fact, one tends to be the controlling number in most cases. I'll leave it as an exercise.
You plan for ONE major failure.
Sounds good, I don't want to get too involved in this and confuse myself. For once I'll take the advice a lot of people gave me before fundies and not practice lol.
Just admit that you're LAZY...
That too, speaking of lazy... video games and chocolate have done hell to my tech 1 fitness programJust admit that you're LAZY...
ah well, off to play some call of duty MW2
You plan rock bottom to get both divers to the surface on any one remaining tank. Except when you are doing deco, then you plan it to the first gas switch, or to complete your deco on backgas. Except when you are diving with multiple deco mixes, then you calculate the backgas deco to the second gas switch. But then you have to make allowances if you lose your shallower mix, and have to finish up your deco on the deeper mix, but then you get to factor in the team's gas supply, except when you are diving in low vis, on a Thursday, or in a body of water starting with 'G', 'K', or 'W'.
"I before e except after c, or when sounding like ay as in neighbor or weigh, and on weekends, and holidays, and all throughout May, and you'll always be wrong, no matter what you say!" -- Brian Regan
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