Do you actually see people diving with pony bottles?

[The Chairman]

No ... the easier solution is to pay attention to your dive plan,

Learning how to plan a dive seems to be a lost art. They can't follow what you can't create. Most divers say "what's a SAC?" when I ask them what their's is.

 

[MaxBottomtime]

Even if there is no dive plan and the diver forgets nearly everything he learned in OW he should still be able to look at his spg and know when he needs to head to the surface. There is no excuse for running out of air.

 

[Dan]

First of all, if you are diving 2 80cf tanks down to 500 psi each, then you probably don't have enough gas to accommodate your deco obligation.

I teach that for OW, you should keep 100psi/10 ft of depth for your ascent with 500psi as the absolute minimum. If your dive takes you to 130 ft, you should start up with 1,300 psi. That gives you 800psi to swim away from the boat, 900 psi to get back to the up line and 1,300 to ascend (on a 3,000 tank) That should be enough for you and your buddy to ascend with a safety stop. The presence of a pony bottle does not change this. If you want a longer dive, you and your buddy should invest in bigger tanks, but be careful about that deco!!!

20cf and 13cf tanks should never be used in your gas planning. They are redundancy in case you run out of air AND lose your buddy. If you are truly freaked out, they won't last very long at all. You don't have the gas you think you do.

40cf and above can be used in gas planning, as long as you plan on deco obligations as well. Any decent deco software can sort this out for you. My Petrel does an awesome job telling me what gasses I can use and when. This is the essence of tech diving and not something you should just play with. Learn it right or leave it alone.

Thanks for the tips. 100 psi / 10 ft depth is easy to remember.

 

[The Chairman]

There is no excuse for running out of air.

You say that only because it's true.

 

[markmud]

The reason for the question is that on the odd occasion I have hit the 1000 psi accent pressure set by the op I use with less than 10 minutes left in a 60 min dive.

Hi Coztick,

50 minute dive on an AL80 isn't bad. I understand the issue now.

Thanks,
markm

 

[markmud]

Even if there is no dive plan and the diver forgets nearly everything he learned in OW he should still be able to look at his spg and know when he needs to head to the surface. There is no excuse for running out of air.

Hi Max,

Hmm, simplex very sigilum, lex parsimoniae, and maybe a little Ockham's razor thrown in for good measure?

markm

 

[markmud]

Still enjoying this thread...

I see three camps: Difference Between Optimists, Pessimists, and Realists - Glowball Web Network

Now we just have to find a pony solution that is acceptable to all three.

Quote from your Link:
"Case in point; during the Vietnam conflict, US soldiers who were taken as prisoners of war and held captive undetected for long periods of time. Once our troops eventually discovered these camps and rescued prisoners, the ones who made it (long term) were often realists. In fact after looking deeper into the matter, it was discovered that usually pessimists died first, closely followed by optimists which baffled the command. They thought if anyone would make it, it would be the optimists."

Thanks for the link lowviz,

I don't think you will find a solution to all three (I know you had tongue in cheek).

1) a pessimist takes a 40cf pony on a 130 fsw NDL dive in clear, calm, and warm water.
2) a realist takes a 13cf pony to 130 fsw for an NDL dive because that is all he/she needs and the possibility of something happening are nil.
3) an optimist takes no pony and uses rental gear for a solo dive to 130 fsw.

Yeah, I will cogitate on that some more.

markm

 

[lowviz]

...//... Yeah, I will cogitate on that some more.

markm

Always a pleasure to chat with another fellow realist. A pony (as pointed out above) is nothing more than a redundant 500 psi.

We profess redundancy in gear, "One is none, two is one". But many are fine with one source of the only thing that you really need to stay alive. It is amazing how fast you die when you run out of something to breathe. Tank sizes are just timers. They all time out. I see no difference between my 120's and my 72's as far as safety. Just takes a bit longer for the exact same thing to happen. Newsflash! You are OOG.

 

[Coztick]

Hi Coztick,

50 minute dive on an AL80 isn't bad. I understand the issue now.

Thanks,
markm

Some dives you have to swim more than others be it no current, bad drop, excited buddy and/or photo opportunity ....
I had just never considered the contents of the pony as the emergency portion of my accent gas.
It still seems reasonable to do so.
Most dives do shallow up at the end...50-60ft...so maybe I will go with Pete's X10 rule.

 

[kelemvor]

Always a pleasure to chat with another fellow realist. A pony (as pointed out above) is nothing more than a redundant 500 psi.

We profess redundancy in gear, "One is none, two is one". But many are fine with one source of the only thing that you really need to stay alive. It is amazing how fast you die when you run out of something to breathe. Tank sizes are just timers. They all time out. I see no difference between my 120's and my 72's as far as safety. Just takes a bit longer for the exact same thing to happen. Newsflash! You are OOG.

It also gives you a redundant regulator in addition to the extra gas.