Pony Recommendations
- Thread starter Curly
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
evad:
I have a 40 inch hose on the primary and a 6 inch hose on the SPG. The 2nd stage is deployed and routed from the left around the back of the neck to the right just like my primary which is clipped off to the right shoulder when not in use. This system doesn't work as well with a standard yoke with 36 inch hose.
evad:
Two hoses. Is that what you mean?
The size pony you need depends on your surface air consumption (SAC) rate and assumptions about your ascent with it. Since you'd be using the pony as a bailout bottle (analogous to a skydiver's reserve parachute), you can assume an emergency situation and plenty of stress.Curly:
It's conventional to assume a SAC rate of 1.0 cf/min in a stressful situation, or even more.
For the ascent, I'd assume a minute to get sorted out at depth, 30 fpm ascent rate, 5 minute safety stop, and 300 psi reserve at the surface. This reserve assumption accounts for the 3000 psi tank cooling off or having been breathed a bit for reg checks, plus a little left over for inflating and swimming at the surface.
If you calculate gas requirements for these assumptions, you find that a 13 cf pony would get you up from about 40 feet, a 19 cf pony from about 80 feet, and a 30 cf pony from about 145 feet.
These depths are sensitive to the assumed SAC rate. If you increase the assumed SAC rate just 10%, to 1.1 cf/min, these depths rise to 30 feet, 70 feet, and 130 feet for the 13, 19 and 30 cf pony bottles.
If you only have one pony, numbers like these tell me it should be 30 cf to cover any recreational dive. For "shallower" dives, a 19 cf bottle would probably be OK. A 13 cf bottle would only be reasonable for dives that are so shallow that you might not even take a pony along.
Darnold9999
Contributor
IMHO There is no "right" answer to this question. Some think that a spare air is enough to carry as a bailout, others demand a slung 40. Personally I think that if you think it through and figure out how you are going to use the redundant air, and practice with it, there are no wrong choices, just ones that will get you out of fewer bad situations.
SAC, dive profile, type of diving, age, fitness, tolerance for risk all figure in to the calculation you must make to figure out what size is right for you and your diving.
SAC under extreme stress will be much higher than your normal SAC.
5 dives a day or only one will determine if you need to figure in a long safety stop into your calculations. Only one most people can probably skip the safety stop in an emergency.
Vacation diving - a 30 is a bit hard to travel with, yes you can rent, but not everywhere.
Age - older means skipping safety stops and a faster rate of ascent are not a good idea so bigger is better.
Personally, if my calculations tell me that I am going to need a 40 it is time to look into diving doubles.
After all of this I went with a 6 - to be bailout bottle only. My thought process was mostly I dive shallow, I am comfortable with CESA as my final option, I will skip the safety stop, I rarely dive below 90 feet and if I do I don't stay there long, I will accept the risk of a minimal safety stop, I will accept the risk of a 60 foot a minute ascent. I am over 50, but in very good shape so carry few risk factors for such an ascent. The real decision point was travel. I travel quite a bit to dive and am not prepared to travel with a larger bottle. For local dives I am seriously contemplating a second larger bottle, but it will be a 13 or 19 not a 30 or 40. Risky - yes, bigger is almost always better and nobody died from having too much air, but end of the day travel convenience won out. I also dive cold with a dry suit so the weight of another tank is an issue. I am already carrying more than 75 # of gear into the water. Yes it is all neutral once I get to the water, but the hike to and from the water is not easy and adding another 30 pounds for a pony is just not going to happen.
Let the games begin
SAC, dive profile, type of diving, age, fitness, tolerance for risk all figure in to the calculation you must make to figure out what size is right for you and your diving.
SAC under extreme stress will be much higher than your normal SAC.
5 dives a day or only one will determine if you need to figure in a long safety stop into your calculations. Only one most people can probably skip the safety stop in an emergency.
Vacation diving - a 30 is a bit hard to travel with, yes you can rent, but not everywhere.
Age - older means skipping safety stops and a faster rate of ascent are not a good idea so bigger is better.
Personally, if my calculations tell me that I am going to need a 40 it is time to look into diving doubles.
After all of this I went with a 6 - to be bailout bottle only. My thought process was mostly I dive shallow, I am comfortable with CESA as my final option, I will skip the safety stop, I rarely dive below 90 feet and if I do I don't stay there long, I will accept the risk of a minimal safety stop, I will accept the risk of a 60 foot a minute ascent. I am over 50, but in very good shape so carry few risk factors for such an ascent. The real decision point was travel. I travel quite a bit to dive and am not prepared to travel with a larger bottle. For local dives I am seriously contemplating a second larger bottle, but it will be a 13 or 19 not a 30 or 40. Risky - yes, bigger is almost always better and nobody died from having too much air, but end of the day travel convenience won out. I also dive cold with a dry suit so the weight of another tank is an issue. I am already carrying more than 75 # of gear into the water. Yes it is all neutral once I get to the water, but the hike to and from the water is not easy and adding another 30 pounds for a pony is just not going to happen.
Let the games begin
OP
Curly
Contributor
Thanks for all the insightful responses. My initial thought, and the recommendation from a guy I know at one of my LDSs, was the AL 30. One of my regular buddies carries a 30, while another uses a 19. Better to have more, I suppose. My primary reg is all AquaLung, so I am considering the same for the pony.
Thanks again.
Thanks again.
hazmatmess
Contributor
I went with a 30 for a few reasons:
1) I'm not a small guy so I use a little more air so I want to make sure I have enough if needed.
2) My dives take me anywhere from 25' to 130' so I wanted to make sure that I can get out of any emergency situation.
3) You can never have enough air.
Thats just me, for each person its different. Some people told me that a 30 for them is too heavy and too big. For me, its a great size and after a couple of dives, I don't even know its there anymore.
Enjoy,
Tim
1) I'm not a small guy so I use a little more air so I want to make sure I have enough if needed.
2) My dives take me anywhere from 25' to 130' so I wanted to make sure that I can get out of any emergency situation.
3) You can never have enough air.
Thats just me, for each person its different. Some people told me that a 30 for them is too heavy and too big. For me, its a great size and after a couple of dives, I don't even know its there anymore.
Enjoy,
Tim
Similar threads
