Pony/Redundant Set-up

[lg56]

The man is only trying to educate himself with a particular piece of equipment. The only stupid question asked was from Wu, excuse me.. Dr. Wu. Must be a highly educated man.

 

[lg56]

Caveman,
I came to this discussion for the same reasons you did and can't imagine anyone offering such a dumb ass remark as Wu. I did see some very helpfull responses and I hope most of your questions were answered. I have been diving the Oriskany for a few years with singles and I have always thought perhaps some redundancy may be a good idea. I think I will look into a 19 cu.ft. bottle and attach in sidemount fashion. Good luck!

 

[drdaddy]

Here, I will offer my 2 cents. I don't mean to pick on Elan, but I think we can discuss differences of opinion without pissing on each other as it tends to happen with some others zealots on pony bottles.



If you assume the diver stressed and consuming 1 cu/ft per minute and wants time to work things out on the bottom and do all deep and safety stops, then you are correct that a 19 is not big enough at 100'. This is a big issue with pony bottles, unless you know your SAC and have a pony ascent plan in place, then the size increases insanely as you add all the extra buffers such as fumbling around at depth for a minute to "work things out".

However, if you know your SAC and practice with the pony on a regular bases, the amount of air needed is much less. I personally can do all my stops from 100' on a 6 cu ft bottle, now don't read this as an endorsement of 6cu ft for a 100' dive as that is under ideal conditions and no tolerance and could get you killed, just saying that a 30 may be overkill IF YOU PRACTICE AND KNOW YOUR AIR USE FOR ASCENT.




First, if I bail out on a pony, my diving is done for the day, maybe a lot longer. A major issues happened and I will not continue to dive until I understand why it happened and have some serious soul searching. No reason to plan a pony big enough to allow me to screw up 2 sequential dives.

The is some logic to buying a 40 for use as a stage, as long as you don't plan on traveling by air with it. I own 3 pony tanks including a 40, different sizes for different uses.



I agree, its not a cost issue. If the 40 works for you (meaning you don't travel by air and don't mind the extra size and weight (topside) fine. Once you set up one size to sling, you can add another bottle cheap enough later if you want more flexibility.



Not always true, many systems connect to the tank bands with quick releases. So if you need to swap tanks, its 30 seconds or so. Plus many larger boats have compressors depending in your location, so the whole tank switch becomes moot. My mounting hardware for back mount was about $25, so the cost is about the same as stage rigging.

GrumpyOldGuy - 19cf is enough for 100ft bailout.

I was just going to write, but you said everything I was going to say. Especially the part about having to use the pony as a bailout once - and not going down again until there was a serious analysis and self-talk/chewing out about what in the heck happened down there - and how it will never happen again!

thank you for saying it all,
drdaddy

 

[elan]

You might be bailing out another person not yourself. I once bailed out my friend, I gave him my primary on a 5' hose and used the pony his diving was done for the day. I could have got back to the water again if I had other buddies

 

[GrumpyOldGuy]

You might be bailing out another person not yourself. I once bailed out my friend, I gave him my primary on a 5' hose and used the pony his diving was done for the day. I could have got back to the water again if I had other buddies

I guess if you goal is to never miss a dive despite having buddy's run OOG then maybe you should have an AL40. That goal is not on my radar, but then again I tend to dive solo so its not an issue for me.

 

[turnerjd]

With all due respect to Dr Bill, in my very own personal and humble opinion, this would be an entanglement hazard.

I don't agree. I quite like drbill's setup, it looks good. The pony is tucked away by the left kidneys, upside down, hose coming up on the RHS. It looks to be nicely out of the way, and well held in place. The risk of entanglement is far lower than for normal side by side pony attachment. This for me is one of the better tank mounted pony setups I have seen. If I was to go back to diving with a pony I would seriously think about setting things up like this.

What depths do you dive to drbill? If you are doing long research dives not too deep than I can see that the AL19 is probably ok, but is it not a bit small for deeper dives? What is that in metric? 3L? I would of thought that a 5 or 7 L pony would be better, I think that most of the Faber steel pony tanks sold in europe are this size. What is that in cuft? 30 or 40?

Jon

 

[markmantei]

GrumpyOldGuy - 19cf is enough for 100ft bailout.

I was just going to write, but you said everything I was going to say. Especially the part about having to use the pony as a bailout once - and not going down again until there was a serious analysis and self-talk/chewing out about what in the heck happened down there - and how it will never happen again!

thank you for saying it all,
drdaddy

Is a 19cf large enough for 100ft dive in an overhead (ice)? That is the environment the OP is speaking too. I agree that a slung 40cf would be the better choice.

 

[nimoh]

I would go for the 40 over the 19. There is a small discomfort added by carrying a stage bottle (a little heaver, more time to assemble gear, etc), however the difference between a 19 and a 40 in this respect is negligible, so why not carry double the air.

When I first started carrying a stage, I used an 80 and got used to it. Now, when I use a 40, I sometimes forget I am carrying it (unless I want to use it).

For what its worth, I have mine rigged with a DIR stage rigging that can be cut off quickly with a knife if necessary, and mounted on my left chest D-ring, and left hip d-ring. I'd like to post a picture of my setup, but I don't have one around, and I'll probably forget to do it later

 

[GrumpyOldGuy]

Is a 19cf large enough for 100ft dive in an overhead (ice)? That is the environment the OP is speaking too. I agree that a slung 40cf would be the better choice.

You do realize this is a zombie thread, over a year old?

Anyway, the OP never said anything about an overhead environment, much less ice. That would change things.

The reply I made was in the context of someone claiming you needed a 40 so you could continue your dive day if you had to donate gas to buddy, a weak argument at bast. Personally I have 3 different sizes of pony bottles, there are too many types of environments and needs to lock yourself into a one size fits all mindset.