What size pony tank for 130'?
- Thread starter SlyStrat
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Do the calculation given your own parameters? Or search “rock bottom” or “min gas.”
AL40
AL40
What @grantctobin said ... run the calculations using your own sac rate. With that said, from 130' I'd expect you will want an AL40.
At least a 30, preferably a 40. Is this a planned deco dive or is this a touch 130 and then go shallow dive?
This past summer I had an incident at around 100 feet. From beginning of incident, clearing my accidentally acquired 2 minute deco and safety stop, from beginning to back on deck, I used 26 CF. My usual 19, which I did not have because I was not intentionally solo, might not have gotten me to the top without skipping my safety stop and deco stop. I try to carry 1/3 of my back gas rounded up but get lazy sometimes and just use my 19 because it is so handy, and normally enough for shallower dives. So for an 80 cf tank that is a 30. I am assuming you are single tank 80 to 100 or so cf?
James
This past summer I had an incident at around 100 feet. From beginning of incident, clearing my accidentally acquired 2 minute deco and safety stop, from beginning to back on deck, I used 26 CF. My usual 19, which I did not have because I was not intentionally solo, might not have gotten me to the top without skipping my safety stop and deco stop. I try to carry 1/3 of my back gas rounded up but get lazy sometimes and just use my 19 because it is so handy, and normally enough for shallower dives. So for an 80 cf tank that is a 30. I am assuming you are single tank 80 to 100 or so cf?
James
When I teach Solo Diving, once I know my students SAC rate we make a table showing how long each cylinder size will "last". Spare Air (useless) 20 cu ft 30 cu ft and 40 cu ft.
Remember in an emergency situation your SAC rate will increase by 50% or even 100%.
Do your math, once you get to 100ft or below you will find a 30 cu ft might do it but you will probably go for a 40 cu ft.
This was from my last course. ( Sorry about the formatting)
Remember in an emergency situation your SAC rate will increase by 50% or even 100%.
Do your math, once you get to 100ft or below you will find a 30 cu ft might do it but you will probably go for a 40 cu ft.
This was from my last course. ( Sorry about the formatting)
| All Pony sizes fill to 3,000 Psi | Time in minutes based on 0.50 SAC (cu ft / min) | ||||
Actual Capacity | Surface 1 ATA | 40 Ft 2.2 ATA | 60 Ft 2.8 ATA | 100 Ft 4 ATA | |
| 80 Cu Ft | 77.6 | 155 | 71 | 55 | 39 |
| 40 Cu Ft | 40.0 | 80 | 36 | 29 | 20 |
| 30 Cu Ft | 29.0 | 58 | 26 | 21 | 15 |
| 19 Cu Ft | 18.3 | 37 | 17 | 13 | 9 |
| 13 Cu Ft | 12.8 | 26 | 12 | 9 | 6 |
| 6 Cu Ft | 5.8 | 12 | 5 | 4 | 2.90 |
| 3 Cu Ft "Spare Air" | 3.0 | 6.00 | 2.73 | 2.14 | 1.50 |
| 1.7 Cu Ft "Spare Air" | 1.7 | 3.40 | 1.55 | 1.21 | 0.85 |
My "flying" 19 makes for a pretty reasonable bail out at 60ft nominal dives. At 100+ it is realistically skip-breathing assisted-CESA during the first part of the ascent. But not unreasonable to be able to maintain a 30ft/min rate and have enough to do a short SS as long as it it a straight switch and go up. Way better than bolting. At home/driving it is my 40.
130ft? AL40 minimum.
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