Pony bottle setup/config

[docmartin]

to those who keep elaborating on why one should stay away from ponies: sometimes you don't have much of a choice if you want to dive. many if not most NJ dive boats require doubles or a pony. if you can't afford the doubles or have not had the training then you either use a pony or don't go diving. i had rather use the pony. the northeast boat captains who tend to cater to experienced divers apparently think it's safer than diving without a redundant air supply. ever wonder where they got that idea?

 

[docmartin]

forgot to ask if anyone had used the spg type that screws directly into the hp port without a hose. seems to me like this method would always be preferable to having an spg with a 7" hose bungeed to the first stage. fewer failure points, less entanglement hazard, more straemlined. however, according to all the pictures i have seen it does not seem to be DIR (of course, ponies never are but i am talking about the stage bottle setup you see on DIR web sites. as far as rigging the same logic should apply to stage bottles and ponies).

 

[Epinephelus]

docmartin once bubbled...
forgot to ask if anyone had used the spg type that screws directly into the hp port without a hose. seems to me like this method would always be preferable to having an spg with a 7" hose bungeed to the first stage. fewer failure points, less entanglement hazard, more straemlined. however, according to all the pictures i have seen it does not seem to be DIR (of course, ponies never are but i am talking about the stage bottle setup you see on DIR web sites. as far as rigging the same logic should apply to stage bottles and ponies).

I've used the peanut gauge - still have one and use it in certain very limited situations. But it has become difficult to read, so for most applications I use the full-sized SPG on a 7" hose - not because I need that level of accuracy - as in many of my diving decisions, I do it that way 'cause I want to.
E.

 

[Epinephelus]

ElectricZombie once bubbled...
The people who are insecure with their diving practices are the same ones who buy pony bottles. I'm not trying to sound mean, but this is just how it is.

Horse manure.
E.

 

[jepuskar]

Thanks for comments...both pro/con.

The person I am going to Bonaire with will be a relatively new diver..less than 30 dives by the time we go...I only have a 100 dives under my integrated weight pouches.

We will break 60 feet on the vast majority of dives and I concluded that if both of us each had a pony bottle that would just be 'safer'. As far as it not bring true redundancy..I dont understand that....separate tank, separate reg....that seems pretty redundant...granted it is not as much gas, but if it was ever needed it would be there.

I also dont understand why some people dive with the pony off.

Hey, let me branch off here for a sec....people talk about mounting their ponies upside down, but what about your main tank? I have never seen a diver with a single tank mounted upside down..why not?

 

[Epinephelus]

jepuskar once bubbled...
As far as it not bring true redundancy..I dont understand that....separate tank, separate reg....that seems pretty redundant...granted it is not as much gas, but if it was ever needed it would be there.

"True redundancy" implies equality. So a 13CF pony filled with back gas only becomes "truly" redundant when you hit 13CF in your 80 (500 psi). Likewise, a 19 is "redundant" for 725 psi and a 30 is redundant for 1200 psi etc.

I also dont understand why some people dive with the pony off.

This is just to prevent the accidental loss of the gas in the pony through an unnoticed freeflow.

Hey, let me branch off here for a sec....people talk about mounting their ponies upside down, but what about your main tank? I have never seen a diver with a single tank mounted upside down..why not?

The only real reason is that it's a potential disaster out of the water. In the water, bottoms up tanks are less likely to become entangled, can be positioned so that they don't bump your head, are *much* easier to reach for valve manipulation... in short, if you didn't have to deal with 'em topside it would make a lot of sense. BUT - they are such a major pain in the tail to rig, don, carry and doff above water - and have such high potential for equipment damage - that it just isn't worth it.
E.

 

[Spectre]

jepuskar once bubbled...
I also dont understand why some people dive with the pony off.

I do because it is good practice for the future; as far as switching to deco gasses and being in the habit of turning the tank on and taking the reg. Another reason, expecially with a smaller pony, is that you have very little precious air. If you have a freeflow when jumping in, or hitting a thermocline, or bumping something/someone and purging... you could loose a bit of air.

When I had the tank mounted on my back, I had the reg against the tank. If that reg freeflowed, I might not notice what was freeflowing right away to be able to stop the freeflow before I loose a good bit of gas.

Hey, let me branch off here for a sec....people talk about mounting their ponies upside down, but what about your main tank? I have never seen a diver with a single tank mounted upside down..why not?

Well, since your main tank is most likely going to be on when you are diving, and you should be able to reach the valve, you don't need it upside down to reach the valve. With a back mounted pony, you can have it up at the same level as the valve on your main tank, but most likely that won't be balanced on your rig and will flop around too much. You'll probably find that the balance point is low enough that you won't be able to reach the valve. Even if you can reach the valve, it will most likely be difficult. If you have a need for that bottle, you will want to deploy it quickly.

If you have it upside down, it's easy to reach to turn on the valve [if you dive with it off]. Think this one out... what happens if you have a problem and need to switch to your pony. What happens if it's in an inconvenient place to reach the valve? What happens if you forgot to turn it on?

Regardless of if you dive with it on or off, you'll still want the valve in a quickly accessible area in case you need to turn it on or off. The difference between this and a main tank is that a main tank that is off is noticed quickly... A pony isn't noticed to be off until you've already got serious problems.

So my full feeling is you want to have it in a conveniently reach place, and keep it off so that the deployment procedure is "grab reg, turn on tank, breathe", so you never have a surprise when you get to the breathe portion and you can't.

 

[Doc Intrepid]

Jason,

My .02 cents worth basically is a "me too" to Jeff and several others above.

This issue is a debate, and it is not a question of right or wrong - but rather which argument do you personally find more compelling?

"Pony bottles are not a real solution and that is simply a fact".

I respect Jonathan Mitchell's right to his opinion, but I disagree with him. Bail-out bottles or pony bottles can be a real solution. It depends a great deal on your circumstances.

I have a black Luxfer 30 cu ft bottle that I carry in the exact same manner as Rick Murchison, above. If technical diving it can be a (small) stage/deco bottle. Under different circumstances, e.g. when boat diving with a perfect stranger, you can call it anything you'd like. Its slung like a stage, with a 2nd on a 40" hose, with a nitrox mix good to maximum no-decompression depths. I don't plan to use it, but its available if something unforeseen happens. Very few divers go diving planning on enduring some crisis at depth. Crises have a way of occurring from time to time anyway. And with respect to buddies, what 'should' be isn't always the way things actually wind up being, for many different reasons. Personally I'd rather plan on my buddy being there but be prepared in the event that my buddy isn't; rather than only planning on my buddy being there.

Its a personal choice.

In my humble opinion, which way you decide depends on your personal philosophy. Some divers apparently dive in a utopian world, where they believe they have an element of control over events (above the surface and below it), their dive plan will always work precisely the way they planned it, emergencies occur the way they were practiced in the pool, and they do not dive if conditions are less than ideal. Other divers dive in the real world, where they realize they have very little control over anything and conditions are seldom anywhere near ideal - but the alternative is to not dive at all. On the expensive vacation you've been planning for months. Despite all the things you cannot control, one small thing you do have control over is how much gas you take down with you.

Before you purchase that 13 cu ft tank you've had your eye on, however, take a minute to calculate your Surface Air Consumption (SAC) rate or Respiratory Minute Volume (RMV) rate. Consider that under high anxiety, it might be a tad higher. Then figure out how many minutes of air that 13 offers. I suggest you then compare that to how many minutes of air that 19 offers. And, how many minutes it would require you to make a safe ascent from, say, 100'. With a safety stop at 10'. All said and done, if you're going to take a small tank at all with you to Bonaire, the 19 offers benefits the 13 doesn't. My opinion only.

Sorry for the diatribe. FWIW. YMMV.

Doc

edited for typos

 

[Rick Murchison]

Epinephelus once bubbled...
"True redundancy" implies equality. So a 13CF pony filled with back gas only becomes "truly" redundant when you hit 13CF in your 80 (500 psi). Likewise, a 19 is "redundant" for 725 psi and a 30 is redundant for 1200 psi etc.

The use of manifolded doubles or an "H" or "Y" valve with two independent regulators is considered true redundancy as well, because in the event of a regulator failure or freeflow you can shut down the bad one and still have access to all your gas - even better than independent doubles, which provide "true redundancy" for only half your total gas at best.
Rick

 

[jepuskar]

In a computing world, true redundancy would entail having an exact backup system to take control in real time in case of some catastrophic failure with no loss in performance.

In the diving world, I don't consider a true redundant backup source to have these same attributes.

If your main system fails, a redundant system would be a system that is totally independant of that failed system. Having a pony tank with a seperate regulator is a redundant system. Having a pony tank with ample air supply to safely make it to the surface is a TRUE redundant system.

I thought it was generally a good idea to abort your dive if your main system fails??

In this case, having another tank of the same size as your backup really does no good...that is unless you plan on continuing the dive. Having a seperate system with ample air supply to reach the surface safely is a redundant system