GUE/DIR Standard Deco Gas Sequence

[jjones9527]

Please help me understand your response. We use 1.5 times the calculated bottom mix gas to provide enough gas to get two dives to the 1st switch. We have since been calculating min gas based on the an actual calculation of consumption (at 1ft SAC X 2) which comes out to less than 1.5 in some cases. Would you need to calculate the deco gas at 1.5 or something less (IANTD uses 1.2) and I think that is because they assume you now have options and could go onto your or your buddies back gas, or other deco gas.

If, in fact, if you did need to use 1.5, you may consider 21/35 as your 80 cf bottle and use two 40's for your 50 and 100. Although that may leave you with less shallow options in the event of lost deco gas shallow. Just a thought.

In the case of a lost deco bottle, the remaining bottle is shared and stops extended 1.5X, hence 1.5 times the gas needed.

 

[allenw1972]

Maybe what is needed is a stage to give greater backgas reserves?



And doing 10 fpm up to 100' doesn't sound like it requires either a 120 or 190 bottle?

I am using V-planner and it just depends on what gas you plug in for the deeper, 1 minute stops.

It wouldn't be good to do the 170'-100' stops on 50% or 100%...unless you like doing the funkey chicken.

I may have misunderstood your response.

 

[Rick Inman]

Maybe what is needed is a stage to give greater backgas reserves?

On the dive I did with Allen Saturday, he had those giant over-filled 130's for backgas, so that wasn't a problem.

 

[lamont]

I am using V-planner and it just depends on what gas you plug in for the deeper, 1 minute stops.

It wouldn't be good to do the 170'-100' stops on 50% or 100%...unless you like doing the funkey chicken.

I may have misunderstood your response.

I think I misunderstood you, I thought you were doing 1 minute stops to 100 with the 120 bottle, not the 190...

 

[allenw1972]

I would be doing the stops up to the 70' bottle with either the 120 or 190 bottle depending on the bottle selected. I said 100' because we were using 40% (not 50%) and I know, 40% is not a standard gas (but a really easy one for us to mix). I may have tipped my hand as to why I wanted to use the 190 bottle. The 190 bottle workes a little better than the 120 with 40% vs. 50%, but I didn't really want to expose myself. No let the flogging begin...

 

[fweber]

I would be doing the stops up to the 70' bottle with either the 120 or 190 bottle depending on the bottle selected. I said 100' because we were using 40% (not 50%) and I know, 40% is not a standard gas (but a really easy one for us to mix). I may have tipped my hand as to why I wanted to use the 190 bottle. The 190 bottle workes a little better than the 120 with 40% vs. 50%, but I didn't really want to expose myself. No let the flogging begin...

Allen,

If you want to discuss the use of non-DIR standard gas at depths other than optimal by DIR protocols, perhaps you should post this in the standard tech forum where you are likely to get more input from individuals you are doing what you're asking about.

 

[allenw1972]

Allen,

If you want to discuss the use of non-DIR standard gas at depths other than optimal by DIR protocols, perhaps you should post this in the standard tech forum where you are likely to get more input from individuals you are doing what you're asking about.

Respectifully...the question was specific to DIR standard gases, and I understand our use of gases other than the DIR standard has no place in the forum. My bad, but I felt it necessary to mention this due to the details of the solution presented and my enlightened understanding of DIR standard gas mixes.

 

[JeffG]

Respectifully...the question was specific to DIR standard gases, and I understand our use of gases other than the DIR standard has no place in the forum. My bad, but I felt it necessary to mention this due to the details of the solution presented and my enlightened understanding of DIR standard gas mixes.

The question was about standard gases, I'll give you that. But to be used in a way that has nothing to do with DIR (and with gases that are not in standard gas mix.)

This topic would be better suited in the generic Technical Diving Specialties, because quite frankly..the answers you would get have nothing to do with DIR. (just decompression)

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