Pony bottle questions

[LowDrag]

You are going to need a 3rd regulator. The pony is not a substitute for the 2nd reg on your primary tank. Think of it this way if you pass your pony to your buddy. you no longer have a backup reg with you. The pony is not part of your gas planning.

I completely understand that I still need two second stages for my main gear setup which I have. As I said in my first post, I recently upgraded my first and second STAGES so I have a first and second stage that would be suitable for a pony. I do not recall if it is considered a "must have" or not but I plan to have an SPG for the pony setup just the same. Regulators are not in question here, that part is covered but thanks for pointing that out just the same.

 

[redacted]

As I said, not sure of Op diving conditions, but in NorthEast where I dive - a free ascent could be just as bad as no gas (floating away into the Atlantic...)

I think it's a fair assumption, for a diver who is just starting to use a pony, shooting a bag and tying it off to the bottom as an emergency up line is not a skill they're proficient with.

I may be taking some liberties here, but there are many places a free ascent is not possible. Personally, I'd take the bottom swim back to the anchor and empty whatever gas I have to do that and breath as long as possible on the anchor, rather than risking a free ascent where i might end up a mile+ from the boat, in potentially seas and weather where they can't see me!





They breath differently because of ambient water pressure. You cannot just assume that if you can breath down to 150 psi at surface, you'll be able to get that same amount at depth. Besides the fact that those margins are way too close to "count on". There really shouldn't be any circumstance where you drain tanks that low - that is the point of planning a dive / diving a plan - the point of contingency planning is to manage gas and dive so that even in worst case scenarios - you are not approaching an empty tank..ever.


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150 psi GAUGE means the 1st stage is seeing 150 psi regardless of whether you are at 1 ATM or 4+ ATM. So then it is just a matter of the regulator's ability to deliver the required volume of gas. But, I agree, a primary tank should never get that low unless there is a failure.

I used to do a fair amount of diving at the Flower Gardens which is 100+ miles out in the Gulf. LOA, OOA (or just lost) was usually a direct trip to the surface with no attempt to get back to the mooring line. The boats required all divers be equipped with surface marker buoys. The crew used a dingy for the ride of shame back to the boat. I don't recall ever seeing a diver surface more than a couple 100 meters from the boat. As I recall the ops there restricted pony size to 30 or less.

 

[dumpsterDiver]

To add on to dumpster diver sorry don't want to fill the thread with quote after quote.

What if you run into a current on your way back to the anchor line, if your on your bail-out you should be heading up to the surface, if your worried about not being seen by the boat crew you should have an smb and or audible device.

Yeah I used to dive in NJ a long time ago. drifting off the wreck when the dive boat is tied into the wreck should NOT be anywhere as dangerous as being out of air at 120 feet. I can see the DESIRE to try to salvage the dive and make a normal ascent up the anchor line, but that would be a low priority for myself. If the diver wants to carry enough redundant gas to handle that kind of contingency, then fine.

The probability of a total scuba failure that demands the use of the pony bottle is pretty small. In that emergency situation, I would not be too embarrassed to just come straight up and have the boat come chase me down. If you have a decent crew and the weather is not terrible, and you shoot the smb during the ascent, the SMB should hit the surface in full view of the crew. It is not that likely that your bad luck would compound and nobody would notice it, popping up near the boat... but it could happen..

 

[BugHunterNY]

150 psi GAUGE means the 1st stage is seeing 150 psi regardless of whether you are at 1 ATM or 4+ ATM. So then it is just a matter of the regulator's ability to deliver the required volume of gas. But, I agree, a primary tank should never get that low unless there is a failure.

I used to do a fair amount of diving at the Flower Gardens which is 100+ miles out in the Gulf. LOA, OOA (or just lost) was usually a direct trip to the surface with no attempt to get back to the mooring line. The boats required all divers be equipped with surface marker buoys. The crew used a dingy for the ride of shame back to the boat. I don't recall ever seeing a diver surface more than a couple 100 meters from the boat. As I recall the ops there restricted pony size to 30 or less.

That's my point. Your gauge may say 350psi at depth, but your second stages would be unable to supply any air to you - again, this isn't for all gear, but at depth this is a very real possibility.


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[NAM001]

You need an spg on the pony. I hink most will agree. Ideally you never will need the pony, You do need to know how much is in it predive which does not need an spg but more inportantly you will need it during the dive. NOthing worse than having a low or empty tank when needed.

I completely understand that I still need two second stages for my main gear setup which I have. As I said in my first post, I recently upgraded my first and second STAGES so I have a first and second stage that would be suitable for a pony. I do not recall if it is considered a "must have" or not but I plan to have an SPG for the pony setup just the same. Regulators are not in question here, that part is covered but thanks for pointing that out just the same.

 

[redacted]

That's my point. Your gauge may say 350psi at depth, but your second stages would be unable to supply any air to you - again, this isn't for all gear, but at depth this is a very real possibility.


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I still do not understand why you are making this so depth dependent. An SPG measures the difference between surface pressure and tank pressure. If it reads 350 and is accurate, then the available pressure is 350 at the surface but only about 300 at 100 ft. Is that the difference due to depth that you are talking about? That is really a rather small difference - within the noise of reading accuracy. Of course, if the "zero" is off on your gauge and your gauge reads 350 when your tank is "empty", then at depth, it might actually be "empty" when the gauge reads 400 psi. Still, a rather small difference due to depth.

 

[Roman_66]

An AL13 is the same as 500 psi in an Al80. Most divers can do a lot with that.

Correct in non-emergency situation.
You can't be just in OOG situation if you and your buddy proper divers. Something unlikely should happened.
AL13 will be not enough for most untrained divers in most cases for proper ascending from 120 ft with all stops. Again - emergency situation for you and probably your buddy.

If I just want more gas, I can sling a 63 or an 80.

Of cause, nobody speak here to use pony as additional gas. If I need more gas, I prefer to use back mounted double

I still do not understand why you are making this so depth dependent.

1-st stage output about 10 ata more than pressure around you. 2-nd stage output mostly equal to pressure around you.
Not expensive 1 and 2 stages may have issues around minimum pressure values (less than 20 bar = 300 psi).
Also gauge accuracy should be taken in consideration.
I think this is why pressure less than 500 psi can be define as dangerous.

 

[luscioman]

I assume you want this for ooa. I personally own a 19, 30 and a 40. The 19 works well as a ooa bottle and should be able to get you up safely from about any depth. It is smaller and easy to sling on drings and to pass to a buddy if needed. I use the 30 and 40 for deco and not ooa.

 

[NAM001]

This statement confuses teh heck out of me.. The first stage regulates to say 150psi over environment. on the surface you have 150# when you go to 100 ft and environment becomes 50# then the reg will be gage would read 100# but the first stage increases the presure to maintain150# over seapresure. Now if you have 150 at 100 and you go to the surface and you dont relieve that presure the secondary presure will increase from 150 to 200psi untill breathed on again..... so where does this 350-psi come from?????

That's my point. Your gauge may say 350psi at depth, but your second stages would be unable to supply any air to you - again, this isn't for all gear, but at depth this is a very real possibility.


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[LeadTurn_SD]

This statement confuses teh heck out of me.. The first stage regulates to say 150psi over environment. on the surface you have 150# when you go to 100 ft and environment becomes 50# then the reg will be gage would read 100# but the first stage increases the presure to maintain150# over seapresure. Now if you have 150 at 100 and you go to the surface and you dont relieve that presure the secondary presure will increase from 150 to 200psi untill breathed on again..... so where does this 350-psi come from?????

I think what BugHunter was referring to is the amount of pressure in the tank required to overcome ambient + IP.

For example, at 132 feet you are at 5 ATM (surface 1 ATM, plus 4 ATM for the water over your head). Your pressure gauge is reading the pressure within the tank, and calibrated to 1 ATM.

So if you add 4 ATM of water pressure (4 x 14.7) you have an additional 58.8 psi of ambient pressure for the 1st stage to overcome... 150 IP + 58.8 = 208.8 psi to take a "normal" breath... looks like he added another 150 to get 350?

Or my math is off

Anyway, I think what he was getting at is the actual pressure reading that you would need to see on your spg to still get that last "normal" breath before it started to breath hard, then stop delivering air all together (at depth).

Best wishes.