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sterlinghe92
01-03-2010, 22:22
When would you suggest getting a pony bottle and what Size?

I have almost 20 dives and im diving almost every weekend with 2-3 or more dives each time

I almost have my AOW and want to continue my edu. and get into tech?

Thanks!!

navyhmc
01-03-2010, 23:04
Rather than the 20 dives, the better question is what type of diving are you doing? Deeper than 60'? might be a good idea. Deeper than 90'? for me, it's a definite to have a back up system. If you're diving in an area that has some snags and the like, it would be a good idea as well.

The best way to think about a pony is that it's a back up nothing more. It's not there to extend you bottom time, it's an emergency escape system. Keeps a deep CESA away, and that's a good thing. Better a fully controlled ascent in a crisis than a relatively uncontrolled one.

Tech has stage and deco bottles, but that's different than a pony. A tank mount is a good way to start-easy to put on, it's where you expect it to be and for most diving it's out of the way.

As for size, I would go no smaller than a 19. depth depnding, a 30 or 40 is your best bet. for most rec, a 30 will do you for almost all you'ld need.

Do a search on the forum for pony system and you'll find a lot of good info on the subject.

skdvr
01-04-2010, 05:15
I agree with Navy on this, that it really depends on what kind of diving you are doing. When I bought a pony I had started doing more diving around 100' and if I had a problem I did not want to have to shoot to the surface from there. The best thing to do is to figure out your SAC rate to see how much air you use and then you can figure out how much air you need to get you safely from depth to teh surface with a safety stop. for most people a 19 is a good size. For me personally I went with a 40 because I knew that I wanted to get into tech diving down the road and the 40 is a great size for a deco bottle, plus I could get plenty of practice carrying it.

I sling my bottle in front of me and really do not even notice that it is there anymore. I never tried to tank mount one, but lots of people do...

Phil

Grin
01-04-2010, 07:12
A pony has to be picked by you to accomplish the goal you intend it to.
Everyone seems to have a different idea of what it needs to accomplish. I have read many say if they have a problem they want their pony to have enough capacity to go get their buddy and then accend. Many realize they might be paniking and suck gas like a freight train if they end up on their pony. Some need capacity to get out of a wreck, or who knows what, and then accend. You have to think out your situation and pick accordingly.
Personally I dive a 13 every dive for depths to a little over a 100 ft. I solo dive virtually all the time and if I go on my pony, I will instantly be on my way up. If I have to abort the safety stop then that's fine with me. I also have a 19 and a 30, both, which I rarly use. As someone else stated, many use their ponies for a little extra bottom time. I don't, but my buddies do it quite often. They use 19s, which actually gives them a little time. My 13 is pretty much good for no extra bottom time and only good for a accent. So it kind of eliminates the temptaion to use it for extended bottom time by not being enough to be worth your while.
There are alot of things you need to think out for yourself on a pony settup. Size, sling or backmount, valve on or off during dives to mention a few.

skdvr
01-04-2010, 08:28
Navy said it is NOT to be used for bottom time extension, which I totally agree with. A pony bottle is there only for emergency's and nothing else. Also using it as an ascent bottle is also silly in my opinion, especially if you are solo. I am not sure if you meant it that way or not but it sounded like you use your backgas and then switch to your pony for the ascent. That leaves you with NO backup in case of a failure or any sort of emergency. Skipping the Safety Stop is not the smartest of things to do on any dives especially dives over 100'. If it is a true emergency and you do not have enough air then by all means continue up at a nice slow rate but I would not be making a habit of skipping safety stops. I do them on all dives if noting else just for practice and so that the people diving with me get some practice.

Put the Pony bottle on and do not use it unless you really have to.

Phil

navyhmc
01-04-2010, 08:48
I also sling mine. Like skdvr, I really don't even notice it. I hesitate to suggest slinging to a newer diver due to additional task loading. Not diising you Sterling, just saying. 20 dives is a good start, keep it going! :smiley20:

The only time I've used mine is when I've practiced a OOA incident at depth. I also want to see what restrictions I'm going to have with the OOA crisis I simulate. I can get from 110' to the surface on a 19 IF I don't do a deep stop but I can make it with a safety stop only.

If you really want to try a practice event, and you're deep/AOW cert or equivalent: Go to 130'. OH CARP!!! You're out of air and you're a little negative. Try to start to the surface with that little bit of negative bouyancy. See how hard you're breathing by the time you get to shallower water. You don't need a pony for this drill, just make sure you havea buddy standing by with you that's not partaking in the drill. :smiley20:

scubadiver888
01-04-2010, 08:56
sterlinghe92,

You've dropped yourself into a topic prime for information overload. A lot of agencies, PADI in particular, don't teach 'proper' gas management. Some divers feel that you need to have enough air (gas) to handle the worst case scenario.

Your SAC rate is your Surface Air Consumption rate. You have to figure out how much air you would typically consume on the surface. What you can do is go to 33 feet (10 metres) then do a typical dive staying at that depth. Note how much air you have when you start, how much you have when you end and how long you went for. Next, convert the PSI (or bar) into cubic feet (or cubic litres). Divide the cubic feet used by the number of minutes to come up with cu.ft./min @ 2 ATA (33' or 10m). Divide the number by 2 to get cu.ft/min @ 1 ATA or your SAC rate.

Now you can calculate your gas consumption for any dive. If you dive to a wreck at 107 feet, this is 107/33 + 1 ATA or 4.25 ATA (round up). If your SAC rate is 0.78 cu.ft./min then at 4.25 ATA it would be 3.315 cu.ft./min. If your tank is an AL80 it holds approximately 77 cu.ft. of air. So the cylinder will be empty in 23 minutes. You obviously don't want the cylinder to be empty. If you use the '500 PSI' rule then 500 PSI / 3000 PSI * 77 cu.ft. = 13 cu.ft. So you can use 77 - 13 or 64 cu.ft. of the air. 64 / 3.315 = 19 minutes. You need air for a safety stop. You need air to get down, air to get back up. What about emergency situations?

This is typical gas management. Now lets flip things. Rather than figuring out how much time you have with your AL80, fix the time and figure out how much air to bring down. If I figure out that I want 20 minutes on the wreck I might decide to use an HP80 (it is really 80 cu.ft. rather than 77 cu.ft.) and then a 13 cu.ft. pony bottle for safety.

If I'm penetrating the wreck, worst case is I get lost or trapped. I'd probably consider an HP100 and a 19 cu.ft. pony bottle. If it is a deep penetration I might even skip the pony and dive double HP100s.

A lot of the tech guys I know tend to have a mix of cylinders. They might have: HP130, HP119, double HP100 plus 13, 19 and 40 pony bottles.

Grin
01-05-2010, 09:12
[quote=skdvr;356484]Navy said it is NOT to be used for bottom time extension, which I totally agree with. A pony bottle is there only for emergency's and nothing else."

While I agree with you, and I don't use mine for extended bottom time, it is something that many do. So to not discuss it would be foolish. I must also aggree that done correctly it is no big deal. But I still don't do it. It is a discussion in itself, but since I don't do it, I'll leave that for those who find themselves doing it to justify. Personally I think using your pony to go get your buddy for a emergency accent is foolish, but many prepare that way and to each thier own. Done right, it is not that terrible of a idea.

"Also using it as an ascent bottle is also silly in my opinion, especially if you are solo. I am not sure if you meant it that way or not but it sounded like you use your backgas and then switch to your pony for the ascent. That leaves you with NO backup in case of a failure or any sort of emergency."

My pony bottle is actually 100% for a emergency accent. I do not use it the way you described. You read my post wrong, or I wrote it bad. I have only had to use it twice for emergency accents.

"Skipping the Safety Stop is not the smartest of things to do on any dives especially dives over 100'. If it is a true emergency and you do not have enough air then by all means continue up at a nice slow rate but I would not be making a habit of skipping safety stops. I do them on all dives if noting else just for practice and so that the people diving with me get some practice.

If you dive enough one day you will find yourself in a situation where you either blow your safety stop or use your pony. It's a no brainer to me that if I have the pony avilable to complete my safety stop I'm using it. When I have done this I always switch to my pony before my main tank runs out, to complete a perfect accent. Safety stops are called safety stops becasue they are not required, so if you find yourself in a situation where you need to blow the safety stop, you need not worry. In a true emergency you are better off coming up fast to around 30 ft and then slowing your accent to use whatever gas you have more effectivly than blowing it worrying about trying to complete a safety stop. getting up to around 30 ft fast you will make your gas last alot longer and the expansion of bubbles is much more that last 30 ft. So it's alot more important to go slow the last 30 ft than down deeper for multiple reasons if your trying to get the most out of what you know is a insufficient gas supply.
I am not condoning any of this, it is just fact, that with enough dives you will need to make due with what you have the best you can some day. The first thing you should do in a low gas emergency is cross the safety stop out of your problem.
I have used my pony to not blow a safety stop only a very a few times. I can't remember blowing a safety stop ever. I have never used my pony for extended bottom time. I have only used my pony for accents twice in emergencies, and a few times for practice with plenty of gas in my main tank.
If you choose to use a 13cf pony and have a problem at 100ft, your first computation should be to eliminate the safety stop worries. My 2nd computation would be to get out of 100 ft fast. I would raise to 40ft semifast, and then slowly accend from there to the top trying to use my gas as effectivly as possible from there up. Anyone can swim up from 15-20 ft on one breath if that happens. Hopefully you could blow the safety stop, and slow accend all the way from 40 to 5-10ft on a 13. That is much better than sitting at 15-20ft until your out of air and then bursting to the surface. Once again, so you understand, I'm just spelling out considerations. Of course a 19cf would be optimal at 100ft. But it isn't necessary, and a 13 will work if you know what your doing.

"Put the Pony bottle on and do not use it unless you really have to."

I say yes and no. Of course you don't want to use it. But using it wisly and for any reason at all is better then not using it unless you really need to. As in if you need a little extra to complete your safety stop and a super conservative accent. Or you think you might be cutting your accent short to make it up on your back gas alone. If you think this for any reason you need to go on the pony now, and not wait for the back gas to run out. It's superior to be on the pony with gas left in your main tank than to run the main tank out, trusting switching to your pony settup will go smoothly.
Of course in a perfect world everyone would accend from 50 ft with 1000 lbs of gas left, as they teach you in class. Reality is that is not the norm for most divers. You may not do it, but if you have dove much you don't need to be very observant to realize many come up with nothing in their tanks. I have done it, but I rarly do it these days. But I am not perfect and have found my self on the pony a few times instead of having to do a compromised accent. I've seen many rapid accents by others. Most think noone else saw them do it. A pony is only as good as the person using it. These pony discussions show many have, many different ideas of how to use them, and what they want to do with them. To each their own! Mine is a bail bottle, and if I have to go on it, I'm going up.

skdvr
01-05-2010, 10:36
I do not see myself ever running out of air on a dive unless it happened because of an emergency like entanglement, O-Ring or hose burst. There is no excuse to just all of a sudden to not have enough air. Your dive should be planned so that you have plenty of backgas for your buddy to use for a safe ascent incase they run into trouble. Yeah a good portion of people do not do this which I think is not the best of ideas. They say once I hit 1000 psi I am going to start heading to the surface, without thinking about what depth they may be or where in the water they may be. There is more that goes into planning a dive than saying "I want to get out with 500psi". I do not think I will ever find myself needing to use a pony to complete a safety stop because I did not have enough backgas to do it, unless I encountered some sort of a problem on the dive. If so then that is a very poorly planned dive. I agree that safety stops are not required but they are a very good idea, especially if you are doing multiple dives. I also would not use a pony that allowed me to from 100' to 40' at say 90 fpm and then slow down from there. I would want to have enough gas to make a 30fpm ascent. Is easier on your body to do the fast ascent deeper and slow your ascent as you get closer to the surface? Yes. But that is definitely not a proper way to think about gas planning.

As far as using the pony only when I have to, yes I definitely think you need to use it every once in a while for practice. It does not do you any good if you do not know how to use it.

Phil

Chilkie
01-05-2010, 15:22
Obviously there are lots of schools of thought on this. I always have mine with me. As I often am paired up on dive boats with "insta-buddies", you never know how someone will react in an emergency and having extra air (and an extra reg) could potentially come in very handy.

Tassie Diver
01-05-2010, 15:37
The best time to get a pony bottle is before the start of a dive where you run out of gas!

inventor
01-05-2010, 15:43
The best time to get a pony bottle is before the start of a dive where you run out of gas!:smilie39:

Nah, just get one of those scuba cell phones. And when you run out, order one from Scuba Toys. Just kidding, I'm intending on buying one as soon as the financial situation improves.:smiley20:

navyhmc
01-05-2010, 16:37
The best time to get a pony bottle is before the start of a dive where you run out of gas!:smilie39:

Nah, just get one of those scuba cell phones. And when you run out, order one from Scuba Toys. Just kidding, I'm intending on buying one as soon as the financial situation improves.:smiley20:

Yeah! sounds good...oh wait, no. My cellphone provider doesn't have a underwater coverage. :smiley36:

sterlinghe92
01-05-2010, 17:35
What about sizes? It seams 13 would make since but 19 and 30 is also popular?

Luxfer as a brand also seems good? is that true?

navyhmc
01-05-2010, 17:52
What about sizes? It seams 13 would make since but 19 and 30 is also popular?

Luxfer as a brand also seems good? is that true?

As far as size, I would go with at least a 19.

Look at this thread: http://forum.scubatoys.com/tanks/10435-problems-spare-air.html?highlight=pony+calculator

More specifically a wise post by No Misses:

Spare Air or Pony?
The question that you need to ask yourself is, "What do I need/want this for"?
IMHO, If you are worried about having an OOA (Out Of Air) situation in less than 60 fsw. You can easily do a CESA (Controlled Emergency Swimming Ascent). If, on the other hand, you are planning on doing dives where entanglement, overhead environments, and/or depth might be an issue; a spare air does not give you a lot of time to resolve these situations.

There is some simple math that you can use to figure out what capacity is needed for emergencies.

Let's say that your SAC (Surface Air Consumption) is .6 cf/min (cubic feet per minute)
Your planned dive is 66 fsw (3 ATA) on a wreck where entanglement in monofilament fishing line might be an issue. How many minutes of "Spare Air" will you need to get free of the entanglement and surface?

SAC .6 cf = 1.8 cf at 66 fsw (Gas at depth of 3 ATA is more dense than at 1 ATA)

Small Spare Air is 1.7 cf
1.7/1.8= 0.9 minutes to get untangled and surface

Large Spare Air is 3 cf
3/1.8 = 1.7 minutes to get untangled and surface

13 cf pony bottle
13/1.8 = 7.2 minutes to get untangled and surface

19 cf pony bottle
19/1.8 = 10.5 minutes to get untangled and surface

How much time do you need/want?

Please note that I rounded off some of these numbers. Your Air Consumption will not stay at 1.8 cf/min. When you ascend to 33 fsw your consumption will be lowered to 1.2 cf/min. Also I used .6 SAC as a common reference. Your SAC may be higher or lower. Keep in mind that if you are stressed and strugling, your SAC will be higher than normal. I used 66 fsw for this example. You can put in any depth that you want. At 130 fsw your consumption will be ~5x SAC. SAC is calculated for the surface or 1 ATA - to calculate consumption at depth just multiply by your ATA.

I hope this helps with your decision.

Granted, you may not have an entanglement on a wreck, but it gives you and idea of your time per tank.

A 13 cu ft is indeed small and compact, but for me, the 19 is my minimum. As for manufacturer, Luxfer is the biggest, followed by Catalina and if you want a little wieght, that are a few steel pony/stage bottles out there as well.

workhorse
01-14-2010, 10:34
Im starting to get into Tech as well. I bought a Al 40 with rigging for a deco bottle. The Al 40 has good buoyancy characteristics, near neutral at 500 psi. it is also large enough to get you out of trouble if a failure occurs at depth. I take it long on solo dive as a redundant air source.