On using a small tank to increase bottom time and provide redundancy

[NothingClever]

I've more or less already decided on redundancy, the question is do I use the pony as a range extension or not.

I think you’ve already made up your mind on both topics.

Good luck with getting your “money’s worth” and your diving.

 

[KenE]

Why would you drain a full tank just to get a visual? Especially one that you might not even use for quite some time? Leave it filled, don't worry about an expired viz or hydro until it's time to refill it. Unless of course there will be an issue with an upcoming weeklong livaboard trip or whatever.

I have been fortunate not to need to use my pony for a couple years. The regulator testing draws it down ever so gradually that eventually I need it refilled and it is likely out of viz at that point. To keep the post simple I did not explain why I get the viz on the pony or how often.

 

[NorCalDM]

If you are using the pony as part of your gas planning to extend your bottom time you no longer have redundancy. All you are doing is adding more equipment and complications. Sell the tanks you have and get a bigger ones, keep the pony and treat it as such.

 

[chrisjur]

If you are using the pony as part of your gas planning to extend your bottom time you no longer have redundancy. All you are doing is adding more equipment and complications. Sell the tanks you have and get a bigger ones, keep the pony and treat it as such.

I was so tired of this thread, but this pretty much sums up the issue in the most concise and accurate fashion.

 

[Tom_Ivan]

If you are using the pony as part of your gas planning to extend your bottom time you no longer have redundancy. All you are doing is adding more equipment and complications. Sell the tanks you have and get a bigger ones, keep the pony and treat it as such.

This is incorrect.

If you have two gas sources then you have redundancy. Having a cylinder partially drained doesn't somhow eliminate the usefullness of the remaining gas.

 

[lexvil]

Having not wanted to delve to deep into the redundancy of this topic yet still having my 2 cents…

Pick one extending bottom time or safety based redundancy. If the former use it first if the latter just end your dive when you hit your personal reserve.

 

[Tom_Ivan]

I said almost the same thing but you said it better with less words.

You set me up. I hit it home. Don't worry I'll give you the credit

Pick one extending bottom time or safety based redundancy.....

No. Pick both.
The op will drain one cylinder down leaving enough gas to reach the surface.
He will then drain the other cylinder down leaving enough gas to reach the surface.
He will then proceed to the surface with 2* the minimum gas required to reach the surface.

Thus he has selected to increase bottom time and ALSO increase his redundancy.

 

[SouthernSharktoothDiver]

@Tom_Ivan @LI-er Thank y’all very much! Like, I hate to be disagreeing with so many comments, but a lot of people are just like, “you should just use a bigger tank” with little explanation as to why, and some of them are leveling criticisms based on assumptions that directly contradict my stated gas plan, so I appreciate y’all sticking up for me.

 

[NW Dive Dawg]

@Tom_Ivan @LI-er Thank y’all very much! Like, I hate to be disagreeing with so many comments, but a lot of people are just like, “you should just use a bigger tank” with little explanation as to why, and some of them are leveling criticisms based on assumptions that directly contradict my stated gas plan, so I appreciate y’all sticking up for me.

I'm in the "you should just use a bigger tank" camp if your goal is to simply get another 10-15 minutes of bottom time. The explanation as to why...... is that this will allow your redundant 19cf to be truly and fully redundant throughout the entire dive.... and other than the occasional top-off with a transfill whip, no need for vis inspections or cost to keep the 19 full and good to go.

 

[MaxBottomtime]

I had a buddy who would suck his 130 cu ft tank down, then switch to his pony for the ascent. He would suck it down, then switch to whatever amount he had left in his 130 to surface. He ran out of air multiple times and said he came up on fumes a few more times. He is no longer allowed to dive with us.