Adding a Pony

Reading the thread re: getting rid of a pony bottle, I am thinking about adding one. I am only interested in being self-sufficient for recreational, no-decompression diving. In other words, I can make a direct no-stop ascent to the surface.

So, I am thinking in terms of 13 cf or 19 cf cylinder but I am open to suggestions. I am too old to dive doubles and will primarily use a single HP 100. I MIGHT need to fill a 50# lift bag from the pony should I happen to have a complete wing failure.

I would appreciate thoughts on proper sizing. Weight is a serious consideration. The rig will be used with a DSS BP/W. If you have suggestions re: how to mount the pony to the BP/W (which specific parts to buy), I would certainly like to know.

Thanks!
Richard

Hi Richard. There are lots of opinions on pony use out there and here's mine. Take what you like and leave the rest

I side sling mine so I can see if it is leaking air, work the valve, read the button SPG and hand it off to another diver should the need arise. It sits very nicely, doesn't affect trim and I don't notice it is there when diving. Some brackets are made so you can hand off a back mounted pony in theory but I just did a pool session with someone who is side slinging theirs now because the back mounting bracket was too hard to manipulate in practice (something to test out if you go the back mount route). Here's a link to another thread where I posted a pic of how mine is mounted on page one
http://www.scubaboard.com/forums/advanced-scuba-discussions/258394-pony-bottle-mounting-options.html
You clip it to your left (or right) chest D ring and your hip D ring.

I debated the size of pony to use. Initially I was thinking smaller like you as I also only wanted it for emergency gas in a REC OW situation. After a lot of thinking and discussions though I went with a 30cuft. bottle. This gives a good amount of gas to work out problems UW if they occur (which might more than a straight forward bolt to the surface) and also it is a decent size to later be used as a small stage or deco bottle should one choose to go deeper.

Lastly, I dive with my valve open.

Hope some of this helps,
Dale.

Hi Richard,

I also sling mine for all of the reasons Dale described. I like having it be a "grab and go" item with no effect on my main cylinder set-up / changing routine.

It sounds like you may have a good idea of your typical dives and regardless of your typical buddy dives you may choose to set a more conservative limit for when you are alone. When it comes to sizing more is better but you still need to decide how much more. This old post shows the math behind a typical recovery and the air it could require. Running that exercise for your scenario may shed some light on what you should have.

My 19CF is about 4 pounds negative when full. When sling mounted up front the weight on land is hardly noticeable since it counterbalances some of the main cylinder weight. In general you do not remove lead for this since you may hand it off and would then be under weighted. If you are truly diving alone you may choose to do otherwise or split the difference.

Pete

Thanks for the advice and the link to the pics.

When you sling the bottle this way, what happens with the SPG for the main tank that was clipped to the left hip ring?

Richard

spectrum:

This old post [/URL]shows the math behind a typical recovery and the air it could require. Running that exercise for your scenario may shed some light on what you should have.

Click to expand...

I had seen that post before and forgotten about it. It looks like for that scenario I would need in excess of 22 cf and a 30 cf tank would be required.

I doubt very much that I will be diving beyond 60 feet any time soon as I am much too old to be diving deep. Given that, I think the 19 cf will be my first choice.

Where did you get the mounting system for the 19? Did you just use geared clamps like Dale? That would be pretty easy I suspect. I'll have to look at the dimensions of the harness and tank.

The nice thing about making a choice is that I can easily make a different choice when things change. In the near term 19 sounds right. If I start diving deeper then I'll use a larger pony and dive off of a boat. It's really the surface weight and beach entries that cause me concern.

Richard

rstofer:

Where did you get the mounting system for the 19? Did you just use geared clamps like Dale? That would be pretty easy I suspect. I'll have to look at the dimensions of the harness and tank.

Click to expand...

Assorted spare parts form the divbe ocker and workshop. Cave line, bolt snaps. tubing to make the bottom span a handle, big hose clamp, rubber roofing to keep the hose clamp from scratching, fin strap tubing for the hose clamp head to hide in. I passed on the brass ring for the little 19 and made 2 passes around the neck. maybe sometime I'll do a feature on it for Scuba Knowtes but it's nothing that special. Just as you are doing I looked at several online examples and cobbled things together. Do keep the bolt snaps as close to the cylinder as possible. Gravity will get it far enough away from you.

Whatever you choose to carry for weight do offset it to a side by the 4 pounds or you will notice it.

Pete

All good considerations Richard. In my case the only purchase I regret is my jacket BCD (which I bought before I'd even heard of BP/W's). It does the job but I now see the limited application of it compared to a BP/W. That was what I had in mind when I went with the 30cuft. I didn't want to buy another piece of equipment that would not be transferable down the road. If you know you won't vary your diving profile or if you have the extra cash to upgrade bottles then a 19 would probably do.

Good question about the SPG. Here's a link to just such a discussion.
http://www.scubaboard.com/forums/hogarthian-diving/176046-checking-spg-slung-bottle.html

Richard..... glad to hear an 'old' guy is still diving!!

You have been given some fine advice above.

When I used to dive a single cylinder I carried (slung) a 19cf pony bottle as a redundant gas source. I found this to be a fine size for recreational NDL profiles.

It actually takes very little gas to properly inflate a 50lbs. bag, and that gas should come from your back gas first in the event of a wing failure for several reasons.

I used to charge the line on my pony bottle and then shut off the valve just as I do today with my deco bottles.

Always remember to check your pony bottle reg and on occasion practice with deploying it and using it.

OK, now for the details: I am assuming I would have just a first stage, a single second stage and a small SPG, right?

In the older thread about reading the SPG, there is the comment by Kangy that he never has the pony clipped to his rig while walking on land. Hm... I am thinking specifically about beach entries, crossing parking lots, etc. Do you folks carry the cylinder under your arm with your fins in your other hand? That seems awkward.

Richard

rstofer:

OK, now for the details: I am assuming I would have just a first stage, a single second stage and a small SPG, right?

In the older thread about reading the SPG, there is the comment by Kangy that he never has the pony clipped to his rig while walking on land. Hm... I am thinking specifically about beach entries, crossing parking lots, etc. Do you folks carry the cylinder under your arm with your fins in your other hand? That seems awkward.

Richard

Click to expand...

Right. First stage, second stage and spg is all you need on the pony.

Thankfully, my al30 is mounted to my main, so my hands are free to carry my dive flag and handle, flounder spear and fins and sometimes more.... I'd at least clip the pony somewhere, if I were you....

Dave C