Building 2nd setup. Pony inflater/octo question

[Seand03]

A search on the forum found a 14 year old thread that said this wasn't a good idea. As times change I wanted to re visit this and get some opinions.

Pony bottle for BC & Octopus?

I currently dive an xtek harness intended for doubles w/60 lb wing.

I recently got 10 tanks, a Ranger BCD, doubles bands and manifold, 3 good regs and an extra first stage.

My idea is to use the xtek exclusively for doubles.

I want to use the Ranger for my other diving, but I still want the redundancy of a 2nd bottle. Since I use a camera and don't want other things to worrie about I was thinking about using the pony with my extra first stage as a bcd inflator (bcd has octo on it).
I understand a small pony won't work and I can't hand off this setup. I have a s6, s19, and s50 for ponys. I don't think the 6 will work, too small, and the 50 is too big. Would a 19 throw off my balance significantly? Also would it be enough air for 2-3 dives and still have a reserve in case of emergancy?

I know the most correct response would be depends on how much I inflate... let's assume I'm not overweighted and don't use an excessive amount but some at depth.

In concern to my buddy (wife) she will have the s6 so she has a pony as well. Hers would be on her back with a long hose and tucked somewhere out of the way.


Is my whole though process here wrong? This seems like a great solution to have air redundancy with out any needless complications so I can focus on my diving, my buddy, then photos.


The only possible problem I see besides using up the 19, is if another dive runs out of air that isn't my buddy. Obviously I would try to help them but I don't think I should plan on setting up my gear to better accommodate anyone besides myself and my buddy.

 

[EricTheDood]

I don't really see the point. Seems like you're just convoluting your hose plumbing.

My new setup, based on SB advice, is an AL30 slung like a stage deco bottle and is 100% independent. It won't get used except for emergency situations, thus I won't need to go through the hassle of constantly getting it refilled.

 

[guruboy]

I wouldn't mess with the standard single tank reg setup. Keep the octo and inflator there. Also saves you the trouble of messing with things if you decide to dive without the pony.

If you want redundancy, add a pony with a backup reg on it (for just your use).


Also, I would use bigger than a 6 for your wife, at least a 13.

If you have time, you can run the math and see what you actually need. Calculate your SAC, expected depth, ascent rate, stops, etc.


There was a recent thread about slinging a pony or something. Might have some relevant content for you.

 

[guruboy]

As an example,

assume your SAC is 0.5. Let's double it for stress during OOA situation. SAC=1

Assume you are at 60 feet. Average pressure=2atm.

Assume you ascend at 30ft/min with no stop, with 1 minute to assess. time=2+1=3min

SAC * atm * time

1*2*3 = 6 cu ft

 

[Nemrod]

You do not want to run your BC on your pony if that is your plan, just no.

N

 

[Seand03]

I know a 6 isn't much but I ready have it. I'm not intending that for an emergancy assent, more if she has some sort of ooa situation - like clogged dip tube, broken air gauge, or weird stuck shut valve. Then she would have enough time to get to me, if I'm looking the other way taking a picture.

I did see the post about ponys.

I get its not good to deviate from the norm, but I'm not quite grasping why in this case. If I don't dive the pony I just have an extra octo not in the way. If I am diving the pony besides extra setup work, it just takes the extra task loading of dealing with the pony.

I guess my question is why specifically is this not beneficial?

 

[Jim Lapenta]

Simplicity. Deviation from the norm can complicate rescue situations. You also have to look at what happens if that bottle gets tangled up on something and has to be dropped.

Running your inflator off of a pony bottle is also going to make your hose routing a mess. You'll need to have a hose long enough to go to the inflator and at the same time be streamlined and not looping out in some weird way.

Tech divers will use a suit bottle (6 to 13 cu ft) for the drysuit inflation. I have never seen anyone run a BC off of it.

Giving your wife the 6 is also not something I would suggest. It's like a bigger spare air. Not much more. First of all unless she is practicing deploying it on a regular basis saying that if something happens she will have enough to get to you or get your attention is unlikely. More likely is she will head for the surface. The 19 is better for that.

I'd also suggest you leave the camera at home until you get completely comfortable in your set up and you and your wife have gotten your buddy emergency procedures down.

Here is what I would do if you insist on carrying extra gas.
First, get some training or mentoring on how to set up pony, stage, deco bottles.
Second sell one of those ten tanks and get another 19 and set them up identically for you and your wife.
Keep the six for pressurizing regs to soak and rinse them in the tub.
Do the calculations for your resting and working SAC Rates. Use RMV.
Make sure that her BC is actually set up to allow her to sling a pony.

Having a pony behind your back has been done for years. It does have some drawbacks.
1. You can't see the valve.
2. depending on how you check the pressure in it, you can't see the SPG for it unless you run yet another longer hose somewhere so she can monitor that.
3. Is there a place to stow the second so that if it gets bumped she'll see that it's losing air? If not sling it.

One of the biggest issues I have with pony bottles, and this is because it's what I did, was to just decide to start using one without any real input from someone experienced in all the ways of using them and why this set up was good and this one was not optimal.

It's why I now do that in the AOW classes I teach.

You also state your going to start diving doubles. That means, I hope, at least a good intro to tech class with a tech instructor. Before you start trying to put some kind of non standard set up together for a redundant air supply find that instructor and have a sit down with him/her.

Maybe even do a skills workshop with them designed specifically around the use of redundant air supplies. It does not have to be a formal class. I tailor workshops all the time for people.

I just did one last month where one area specifically addressed was redundant air supplies. No cert card just classroom, knowledge, and practice in the water.

 

[tbone1004]

my question is if you have doubles, and are diving doubles, why would you go back to a ranger of all things with singles and a pony? You're going to be more stable for pictures in doubles than you will be in singles, especially with a weird pony like a 19. The 6 imho is not a safe pony, they are suitable for inflation bottles only, not breathing. Someone did the math up top. Not good. 19's are my personal minimum and I think buying tanks like 13's and 19's is stupid except for rebreathers because they can't be used for anything else. Buy a 30 or 40 and use that which at least has the possibility of being a useful deco bottle if you go that route.

I absolutely wouldn't use a pony bottle as my inflator/AAS if using an Air2, that's sketchy on some insane order of magnitude.

Realistically I would sell the 6 and the 50 because they're basically useless and if you really want your wife diving a pony bottle, give her the 13 and you dive doubles. Nothing wrong with diving doubles all the time as long as whatever boats you are going out on will let you. No equipment changing between dives, same amount of room on the boat, redundancy, etc.

 

[guruboy]

I get its not good to deviate from the norm, but I'm not quite grasping why in this case. If I don't dive the pony I just have an extra octo not in the way. If I am diving the pony besides extra setup work, it just takes the extra task loading of dealing with the pony.

I missed the part where you are using a safe second on the inflator. I though your only octo was going to be on the pony.

Inflator off the main reg still though, for previous reason.

 

[2airishuman]

I was thinking about using the pony with my extra first stage as a bcd inflator (bcd has octo on it).

So, just to be sure I have this straight, you're thinking of diving a configuration like this:

• Backmounted primary cylinder (AL80 or similar) -> primary 1st stage -> SPG & primary second stage

• Backmounted AL19 pony cylinder -> Air2 or similar combined 2nd stage inflator

Is that correct?

Would a 19 throw off my balance significantly?

If I have a slung AL19, I carry six pounds more lead on the opposite hip to maintain trim. For a backmounted AL19 I would think you would need about a two pound difference.

Also would it be enough air for 2-3 dives and still have a reserve in case of emergancy?

I know the most correct response would be depends on how much I inflate... let's assume I'm not overweighted and don't use an excessive amount but some at depth.

Skill aside, it depends on the depth of the dive (because that affects the amount of reserve gas you need), the profile (because a sawtooth profile will involve more BC inflation), and the amount of compensation you need for the weight of gas and for suit compression.

You get a pound of buoyancy for every 0.017 cubic feet or air you put in your BC. If you were at, say, 90 feet, the compression effect would result in you needing about 0.06 cubic feet per pound of buoyancy. If you dove a square profile and ended up compensating for 20 pounds, you would use 1.2 cubic feet of gas. It would be relatively easy to use 2-3 cubic feet per dive with a combination of sawtooth profiles and the use of extra air to maintain buoyancy at the surface before and after the dive. It is hard for me to see how such an arrangement, with no SPG, would provide a dependable reserve after several dives, particularly since an AL19 is already marginal for deeper dives.

In concern to my buddy (wife) she will have the s6 so she has a pony as well. Hers would be on her back with a long hose and tucked somewhere out of the way.

Sticking to the capacity theme here, I do not believe that an AL6 provides an adequate reserve under most circumstances where a pony is necessary. For myself the smallest bottle I use is 13 cf and I only consider that suitable down to around 60 feet.

I dive with my kids and we all dive the same configuration for ease of understanding each other's situation in an emergency, and I recommend that you and your wife dive the same configuration for the same reason.

You should be aware that there have been fatalities involving back-mounted pony cylinders when divers inadvertently breathe the pony reg believing that it is the main reg. I have written elsewhere about the details. I believe that this is a general safety problem with back-mounted ponies that is difficult to overcome completely.

Is my whole though process here wrong? This seems like a great solution to have air redundancy with out any needless complications so I can focus on my diving, my buddy, then photos.

I wouldn't dive that configuration for these specific reasons:

1. I won't depend on any source of air that doesn't have an SPG visible to me during the dive.
   
2. I won't go on a deep dive without a secondary air source on my main dive cylinder(s) because of the possibility of a mouthpiece coming off, broken housing, or other second stage failures.
   
3. I don't believe that using a pony cylinder as a source of BC inflation gas is a safe configuration because there is no standard way of conducting gas planning
   
4. I don't believe an AL19 provides a sufficient reserve under the circumstances
5. I don't believe that your configuration provides a sufficient means of buddy rescue in an out of air situation.

The only possible problem I see besides using up the 19, is if another dive runs out of air that isn't my buddy. Obviously I would try to help them but I don't think I should plan on setting up my gear to better accommodate anyone besides myself and my buddy.

What if your wife needs help because she ran out of air due to a strong current, and doesn't have anything in her pony tank because the strong current caused a freeflow in her pony reg that she didn't notice?

I know a 6 isn't much but I ready have it. I'm not intending that for an emergancy assent, more if she has some sort of ooa situation - like clogged dip tube, broken air gauge, or weird stuck shut valve. Then she would have enough time to get to me, if I'm looking the other way taking a picture.

I don't get it. You posted upthread that you receognize that your own setup doesn't provide the means to rescue an ooa diver.

[various stuff]

I agree with everything that Jim wrote upthread.

The 6 imho is not a safe pony, they are suitable for inflation bottles only, not breathing. Someone did the math up top. Not good. 19's are my personal minimum and I think buying tanks like 13's and 19's is stupid except for rebreathers because they can't be used for anything else. Buy a 30 or 40 and use that which at least has the possibility of being a useful deco bottle if you go that route.

What most people find over time, if they start using a pony, is that there isn't any meaningful disadvantage to carrying a 40 vs. something smaller once you get used to it.