Optimal Pony Bottle Size for Failure at 100ft?

[johndiver999]

Yes 3 simultaneous failures are not something we are going to plan for.

Also, if we think about the super slow ascent, while alone and using a pony bottle..

Why on earth would we want to go super slow? We are very vulnerable to a problem with the pony rig (reg, hose, oring, low fill pressure etc.) since we are alone and have no other back ups. It just makes a hell of a lot of sense to expedite the ascent and get away from the deep zone - where an additional failure can definitely kill us.

If you think about ascending from 130, we are quite vulnerable at 120 (the first pause), but once we get to 50-60 feet, we are within the reasonable strike zone for a gasless, free ascent- should that be necessary.

 

[SpaceX Aquanaut]

Since you're still pushing the issue, I'll keep replying...
Your statement above now presumes THREE failures: gas supply failure, no buddy, and now entanglement.
I don't plan for three failures. An AL40 is just fine for a 130' NDL dive. It's redundant gas. It's plenty for a standard ascent and 15 minutes of deco. If you're indeed NDL diving, then it's even enough for a 60fpm ascent to 60 feet, a standard 30 fpm ascent from there, and a 5 min safety stop for TWO divers.

If you aren't a tech diver, don't want to wait until you get experienced with doubles, but you'd like try something on the edge of your comfort zone with your buddy, I can't think of anything easier and smarter than slinging a 40 CF pony.

I plan for contingencies @rsingler : I dive doubles (redundant gas supply) with O2 AL40 for deco as needed with a DPV every weekend; Solo (no buddy); AND now hyper-situationally aware of fishing line --especially in the depths, surge & murk of the SoCal Oil Rigs.

FWIW, the quick easy calculation below (don't need a spreadsheet @rsingler -can't you handle multiplying by 1 and summing a total?) in the context of post#242 , was meant to show that an AL40 is not enough "margin" from the recreational limit of 130'/39m -and not as "canon" to follow as a strict profile especially with the hazards that I've been exposed to and experienced. . . 10fpm; 30fpm; 60fpm -->y'all have the option to do whatever ascent rate y'all want, applicable to your own diving experiences & hazards you face in your own environment. . .

The table again in US Imperial Units, using 1 cuft/min per ATA volume SAC rate, and 1 minute stops:

4.9 x 1 x 1 = 4.9
4.6 x 1 x 1 = 4.6
4.3 x 1 x 1 = 4.3
4.0 x 1 x 1 = 4
3.7 x 1 x 1 = 3.7
3.4 x 1 x 1 = 3.4
3.1 x 1 x 1 = 3.1
2.8 x 1 x 1 = 2.8
2.5 x 1 x 1 = 2.5
2.2 x 1 x 1 = 2.2
1.9 x 1 x 1 = 1.9
1.6 x 1 x 1 = 1.6
1.3 x 1 x 1 = 1.3
1.0 x 1 x 1 = 1.0


Sum Total: 41.3 cubic feet of Air
An AL40. . .

 

[SpaceX Aquanaut]

however the OP never mentioned going to 39m - you introduced that and then created an argument about it with some obscure ascending regime


might make it if he didnt spend a minute waiting every 3m wasting his gas

Yeah Lermie I prefaced that post#193 with a FWIW hypothetical meant for discussion and illustrative purposes only, and not as canon to follow. 3mpm; 9mpm; 18mpm -->y'all have the option to do whatever ascent rate y'all want, applicable to your own diving experiences & hazards you face in your own environment. . .

 

[johndiver999]

I plan for contingencies @rsingler : I dive doubles (redundant gas supply) with O2 AL40 for deco as needed with a DPV every weekend; Solo (no buddy); AND now hyper-situationally aware of fishing line --especially in the depths, surge & murk of the SoCal Oil Rigs.



The table again in US Imperial Units, using 1 cuft/min per ATA volume SAC rate, and 1 minute stops:

4.9 x 1 x 1 = 4.9
4.6 x 1 x 1 = 4.6
4.3 x 1 x 1 = 4.3
4.0 x 1 x 1 = 4
3.7 x 1 x 1 = 3.7
3.4 x 1 x 1 = 3.4
3.1 x 1 x 1 = 3.1
2.8 x 1 x 1 = 2.8
2.5 x 1 x 1 = 2.5
2.2 x 1 x 1 = 2.2
1.9 x 1 x 1 = 1.9
1.6 x 1 x 1 = 1.6
1.3 x 1 x 1 = 1.3
1.0 x 1 x 1 = 1.0


Sum Total: 41.3 cubic feet of Air
An AL40. . .

This is ridiculous! The calculations are simply WRONG. You forgot the 3 minutes on the bottom that are required to free yourself from fishing line, nets and fight off a Kraken or two.

 

[LI-er]

This is ridiculous! The calculations are simply WRONG. You forgot the 3 minutes on the bottom that are required to free yourself from fishing line, nets and fight off a Kraken or two.

Yes, the calculations are wrong in the extremely unlikely case where a diver is simultaneously entangled/attacked by a kraken AND out of gas in their primary tank.

 

[lowwall]

Yes, the calculations are wrong in the extremely unlikely case where a diver is simultaneously entangled/attacked by a kraken AND out of gas in their primary tank.

No. It was out of gas, attacked by kraken, in a downcurrent, in the dark, with a hole in your drysuit. And kelp.

 

[Tigerpaw]

 

[SpaceX Aquanaut]

Yes, the calculations are wrong in the extremely unlikely case where a diver is simultaneously entangled/attacked by a kraken AND out of gas in their primary tank.

This is ridiculous! The calculations are simply WRONG. You forgot the 3 minutes on the bottom that are required to free yourself from fishing line, nets and fight off a Kraken or two.

No. It was out of gas, attacked by kraken, in a downcurrent, in the dark, with a hole in your drysuit. And kelp.

And mermaids too. . .