Pony questions

[grouchyturtle]

I'm getting a pair of pst tanks soon. Not sure exactly which ones yet. Anyway the plan is to eventually double them, but I don't have the cash for the tanks, a manifold, and a new wing, etc.

So for a while I'll be diving them as singles.

I'm also going to get a larger AL pony, that hopefully can become my shore diving tank, after I double up the steels.

1-What is the largest size tank you would recommend as a pony? Would a 60 be too big? I could probably get away with an AL40 for shore, dives, but figured a 60 would be playing it safe, just a little big as a pony. Do they even make 50s?
2-When diving a pony, do you need 3 regs (primary, backup, and pony), or can I have just my primary on my back tank and the backup on the pony?

 

[IndigoBlue]

I'm getting a pair of pst tanks soon. Not sure exactly which ones yet. Anyway the plan is to eventually double them, but I don't have the cash for the tanks, a manifold, and a new wing, etc.

So for a while I'll be diving them as singles.

I'm also going to get a larger AL pony, that hopefully can become my shore diving tank, after I double up the steels.

1-What is the largest size tank you would recommend as a pony? Would a 60 be too big? I could probably get away with an AL40 for shore, dives, but figured a 60 would be playing it safe, just a little big as a pony. Do they even make 50s?
2-When diving a pony, do you need 3 regs (primary, backup, and pony), or can I have just my primary on my back tank and the backup on the pony?

I have seen pony bottles in the following sizes:

6 cu ft
13 cu ft
20 cu ft
30 cu ft
40 cu ft
63 or 65 cu ft
80 cu ft

The big ones, the 63s, 65s, and 80s, are a huge pain to lug around in the water as pony bottles or as stage bottles. But I have seen it done.

For tech deco diving, the 40s, 30s, and 6s are quite common.

The 6s are usually used as argon bottles.

The 30s are usually used as a single-deco-mix stage bottle for relatively shallow and/or short deco dives, say around 150 ft.

The 40s are the most common sized deco stage bottles used. One to three of these are often imployed in a typical deep or long deco dive.

That leaves the 13s and the 20s as the least likely sized pony bottles that you would ever use for technical applications, in my experience.

The best overall tank for single-tank diving is still probably the steel 72. If you can get one of those, that would be your best bet after you link together your planned PSTs into doubles. The idea of using an aluminum 63 or 65 or 80 for both single-tank diving and also as a stage bottle is not that good of an idea, at least not comfort-wise.

When diving with a pony bottle, yes, you should have 3 second stages and 2 first stages for a single-tank dive. One of the 1st stages is for your main tank, and the other is for your pony. 2 of the 2nd stages are for your main tank, and the other is for your pony. It gets expensive fast.

Uncle Pug may possibly comment to the effect that he and some others believe that pony bottles are not a good idea, and that instead, you should properly manage your gas supply, and stick close to your buddy.

Uncle Pug is usually right. He has been diving for a long time. That would be especially true if you were considering compromising your primary reg system by splitting off the octo and putting it onto your pony. In that case I would agree with Uncle Pug, that a pony, for you, in that mode, would NOT be a good idea.

 

[grouchyturtle]

I wouldn't be using it as a stage bottle just as a pony (not for technical diving). Although I would rig it like a stage bottle.

Once I double my tanks it would be only used as a back tank (shore dives).

I know a lot of the guys here have that same opinion about ponies, but...
Off NJ and LI most of the boats require either doubles or the pony.

If only having the 2 second stages is considered compromising, I won't do it. I just wans't sure what the norm is.

 

[IndigoBlue]

I know a lot of the guys here have that same opinion about ponies, but...
Off NJ and LI most of the boats require either doubles or the pony.
.

Now you have brought up a different issue, the issue of air source redundancy.

Going back to my list of all the different sized stage and pony tanks I have seen, 4 of them make good candidates simply for use as a pony:

6 cu ft
13 cu ft
20 cu ft
30 cu ft

6 is on the small side, and 30 is on the big side. The best choices overall would be 13 or 20 cu ft, for a pony.

On a boat dive, you would simply bring along one of those. I cannot imagine a dive boat requiring it, however, UNLESS YOU WERE SOLO DIVING. In that case, take a look at Robert VonMaier's book on Solo Diving, and yes, he talks about some sort of alternate air source redundancy, such as twin tanks with a shut-off manifold, or a pony.

Even if you are solo diving, you should still have a normal octo on your reg unit. This is because someone else from the boat might swim up to you and demand your alternate air source.

Ergo (as Chickdiver would say), a pony should have its own 1st and 2nd stage, and your back-tank reg should also have an octo 2nd stage on it as well.

Hmmm, this is really getting scary. I am picking up Chickdiver's expressions and Uncle Pug's philosophies. I must be losing my mind?

 

[redacted]

Between you and your good buddy, you should each have enough gas in reserve to safely end the dive in the event of a problem with either diver's gas supply. Your buddy's reserve is usually on your back, and your reserve is on your buddy's back. If your diving solo or have doubts about the reliability of your buddy, same calculations but put your reserve gas in your yellow buddy.

Those who only dive with good buddies, often do not approve of alterative solutions.

I believe an Al 50 is also available, but still awfully big and ackward for a pony.

 

[DA Aquamaster]

Anything larger than a 40 can be really clumsy for use as a pony even if it is rigged as a stage bottle. The 30 and 40 cu ft ponies have the same 4.4 inch diameter - the 40 cu ft tank is just a few inches taller (about the same height as a steel 72.) The 40 will not be much more of a burden as a pony and will be more useful than a 30 for technical diving.

The next step up generally is the steel 72 or steel 50 in terms of diameter at 6.75 inches which is noticeably smaller than a 7.25 inch diameter AL80. An 1800 or 2015 psi steel 50 would be shorter and lighter than a steel 72 and could be rigged as a pony, but would still be a bit bulky in terms of diameter. The 2015's are shorter in lenght than the 1800 psi steel 50's and are a better choice if you go this route.

The bad news is that the 40 is a little small even for a shore dive and the small diameter would make mounting one a little odd. A steel 50 is still a bit small but fairly light and more normal in terms of diameter, but it is still too bulky (in my opinion) for an efficient pony or deco bottle.

One possible option is to buy a set of travel bands and rig your two steel tanks as independent doubles. Then add a manifold in the future when you can afford it. But if the issue is inadequate lift from too small a wing, I would consider postponing the purchase of new PST tanks.

You could instead buy some used steel 72's ($100 should buy a freshly hydro'd and VIP'd 72 in excellent condition and a serviceable steel 72 with a current hydro and VIP can often be had for around $50 to $60) and then invest the $300-$400 you'll potentially save in a suitable wing and either travel bands or bands and a manifold depending on your available cash.

I currently have 20 steel 72's and obviously like them. I have also never had one fail a hydro and you will never lose money reselling one as long as you buy smart. This will let you recover your purchase price on the 72's if you decide to move up to larger tanks. This is a substantial advantage over buying a new tank and having to eat the depreciation if you later change your mind and go with different tanks.

 

[Spectre]

I'm getting a pair of pst tanks soon. Not sure exactly which ones yet. Anyway the plan is to eventually double them, but I don't have the cash for the tanks, a manifold, and a new wing, etc.

You didn't say what size tanks you are talking about. But lets assume E8-130s. Double 130s'll hold about 20 lbs of gas when full. A single 130 and a 60cuft pony would be about 15 lbs.

If your wing is big enough for the single and a pony, why wouldn't it be big enough for your doubles?

For the cost of the pony, you can get a manifold.

 

[IndigoBlue]

You didn't say what size tanks you are talking about. But lets assume E8-130s. Double 130s'll hold about 20 lbs of gas when full. A single 130 and a 60cuft pony would be about 15 lbs.

If your wing is big enough for the single and a pony, why wouldn't it be big enough for your doubles?

For the cost of the pony, you can get a manifold.

Spectre is right on, for a different reason as well.

When I dive with my wife, I give her each of the two steel 72 Fabers, because I want her to have the best of everything, while I dive in my doubles, for both dives.

When you get doubles, it is good to dive with them as much as possible. It kicks your bootie to walk up and down a beach 4 times in one day, but that is good exercise as well.

 

[IzzyTahil]

gunz - With single tank use a 30cf pony slung like a stage. When you double adn do NDLs, get rid of the 30cf since your 2nd tank becomes redundant, and when you do sling, get a 40cf or larger stage tank when you do deep stuff. Anything smaller than a 30 might not be enough to bring you up from depth safely.

 

[grouchyturtle]

Probably 100s or 120s, I'm a little guy.

Spectre brought up another good point. I'm only diving a 30# wing. How much lift would I need with a single and a pony? Sounds like I may need a bigger wing anyway. Starting to sound like it will just be easier and more cost efficient to just go right to doubles.