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chirodoc
10-29-2008, 17:58
What is a pony bottle? I get the spare air thing, but Ive seen it connected to the front of a BC where its easily reached. How is the pony different( I know it ha more air) but is it in back of you like your tank, or can you reach it really easy? I dont get where it goes

FishFood
10-29-2008, 18:00
It's just a smaller (Usually... Really you could call anything a pony.) tank with an independant reg setup.
Type "pony bottle" into Google Images and you can see some various ways to attach it to your tank.

pony bottle - Google Image Search (http://images.google.com/images?client=opera&rls=en&q=pony%20bottle&sourceid=opera&ie=UTF-8&oe=utf-8&um=1&sa=N&tab=wi)

Also, many people "sling" it, or attach it to their harness/BC via a couple clips to the Drings.

fire diver
10-29-2008, 19:24
If you want a fully redundant gas supply in case of emergencies, then get a pony and stay the hell away from "spare-death". Spare air is fine if you are within maybe 20' of the surface, but then you could just CESA that with ease. If you going to go below that, and want an adequate volume of gas to get you SAFELY back up to the surface with a normal safety stop (on most profiles) then get at least a 19cf pony.

ScubaDude
10-29-2008, 23:41
If you want a fully redundant gas supply in case of emergencies, then get a pony and stay the hell away from "spare-death". Spare air is fine if you are within maybe 20' of the surface, but then you could just CESA that with ease. If you going to go below that, and want an adequate volume of gas to get you SAFELY back up to the surface with a normal safety stop (on most profiles) then get at least a 19cf pony.

Chirodoc, as fire diver said, stay away from "spare-death", it's totally useless, ..... I'd get a 30 at the very least.

Be safe.

Duckydiver
10-30-2008, 09:33
I had a spare air. Shortly after I bought it, I sold it.. and bought a 30 cf pony and a used basic reg. All togather it was only a little more for the pony. If your trying to make a choice I wouold advise a pony of any size ( just not 3 cf).

As for "where does the pony go" It can be mounted to your main trank with the reg cliped to your bc. or you can sling it to your bc in the front. Some bc's (like mine) can not accomedate that. So I mount it to my tank.

I hoped that helped.

emcbride81
10-30-2008, 10:14
Yeah go with the 30. I got a 19cuft pony and I wish I would have just gotten the larger one. It would be better than a spare air in an emergency, but more air is more air....and more air is better...which you get with the 30.

Maybe I will turn it into a high percent 02 when I get into technical...

in_cavediver
10-30-2008, 11:32
Do a search for spair air, spair death etc and you'll get more than you ever wanted.

That said, here is a fairly honest appraisel of the equipment.

--- Observations -------
Before looking at a pony or spair air, look up gas management, rock bottom and understand quantitatively how air is used. IE - Surface consumption rates and how depth changes it. Once you see that, we can talk about Surface rates in cft/min. Mine is around .5cfm/min on average.

Now, lets talk depths. Spair air is rec so lets say our dive is to 100ft or 4 atms of pressure. 130ft is 5atm, 66ft is 3atm and 33ft is 2atm.

Now, this is the biggie. If a diver goes OOA, they will be stressed. When stressed, air consumption goes up 50-150% or 1.5x-2.5x the original. For me, I simply double my surface rate. This lasts between 1 and 2 minutes after getting on additional air before returning to normal. I plan for 2 minutes.

----- planning -------

Assume at 100', within NDL etc and go OOA with spair air. At this depth, my normal air consumption rate is around 2cft/min. By going OOA, I am not at around 4cft/min. With spair air, I cannot stay on the bottom 1 full minute. I need to start ascending immediately. If I go from 100ft to 33ft in 30sec, (average depth of 66ft and holding 120-130ft/min ascent rate) I will use 3cft of air and exhaust the spair air and go OOA again.

Do the same for a dive to 66ft. I go OOA and my consumption rate goes to 3cft/min at depth. My ascent will take 1 min @ 60ft/min and use 2cft. I can stay on the bottom at most 20 seconds to make it to the surface.

Now, using a 19cft pony:

100ft OOA - goto pony and stay at depth 2 minutes getting my buddy etc. I used 8cft of air doing that. I then do a standard ascent to 20ft @ 30ft/min. It should take 2.5 minutes with an average depth of 60ft (about 3atm) In this I used around 4cft. I still have 7cft in my pony to do a safety stop. I burn 0.8cft/min of air at 20ft so I can do 3-4 minutes if I want to. The final ascent should take 0.5 - 1cft of air.

------------ more observations -----------------------
From the above situations, you can clearly see the limitations. Spair air is a CESA aid and nothing more. Depending on the depth, you may go OOA again before reaching the surface.

Comparing that to a pony is simple, all it boils down to is the cft of the tank. A 13cft tank which is a small pony, offers a larger delay time and margin for error for roughly the same cost as spair air (so is the 19).

Now, one thing spair air is really good for is this. Its very small and its likely that you'd carry it and have it to use. A bigger pony is just that, bigger. It's one of those questions of whether you'd really carry it. It does no good on the boat.

----------------- My Biases ------------------

At this point, I am beyond a pony. If I think I need a pony, I am taking true redundant air and if solo, a buddy bottle. (full 1/3rd of my bottom gas or more). If you are doing deep rec dives - IE 70ft or deeper, a pony is a good idea. 70ft is the depth where I personally decide I need redundant gas.

Spair air does have its place but its not with *MOST* scuba divers.

Navy OnStar
10-30-2008, 11:47
Spare air does have its place but its not with scuba divers.

This place USED to be with military helicopter crews but even we got rid of them due to some peculiar quirks. We now use the HABD system made by U.S. Divers which is very similar to a Zeagle Razor with a smaller tank. We only use them to give us a few breaths incase we crash in the water. Helicopters are top heavy and tend to flip over on impact and sink. They give us enough air to undo the seatbelt ditch the door and ascend to the surface from about 30ft.

fire diver
10-30-2008, 15:58
I found a spaire air in the MRAP I was in last month. I wished I had my camera with me at the time. It would be the only time you'd ever see me with one in my hand.

It was there for the same reason as listed above. If the vehicle rolled over into water, a person in the back could use it to find thier way out of the vehicle.

ScubaToys Larry
10-30-2008, 16:06
Obviously, I'd much rather sell someone a pony bottle, another reg, gauge, pony attachments, etc - than a spare air. It will cost much more! But that being said - I have taken a 1.7 spare air from 100 feet to the surface. And when I travel - these days, carrying an extra 30 lbs of gear is pretty much impossible - so I do carry a small spare air with me. I'd much rather have a few cubic feet of air with me than 30 cubic feet in my closet. And I know, have tested that it is enough air to get me up to the surface.

In a real emergency, will I breathe harder?? Sure - but I'll probably swim faster too. Will I have enough air to do a deco stop? Probably not - but people recover from the bends... drowning... not so much. Would I rather have 19, or 30, or 40, or 80 or 120 cubic feet of extra air... sure.... but it's not practical for the traveling and diving I do.

Just another take on it...

emcbride81
10-30-2008, 17:17
You are right Larry, to have that extra bit of air is better than nothing at all. I know I am looking at it from the perspective of local diving, which is what I do most of the time. That allows me to bring whatever I want. Now, like you said, if you travel you aren't going to take a 19-30cft pony...at least not the majority of us.

That is a different perspective than I have had before, I guess I may stop knocking Spare Air now. I can see the benefit with traveling.

Are there any restrictions on carrying Spare Air in luggage like there are for cylinders?

fire diver
10-30-2008, 17:28
You are right Larry, to have that extra bit of air is better than nothing at all. I know I am looking at it from the perspective of local diving, which is what I do most of the time. That allows me to bring whatever I want. Now, like you said, if you travel you aren't going to take a 19-30cft pony...at least not the majority of us.

That is a different perspective than I have had before, I guess I may stop knocking Spare Air now. I can see the benefit with traveling.

Are there any restrictions on carrying Spare Air in luggage like there are for cylinders?

Yes, the same rules apply. But you can get a cross-fill whip and fill off you dive tank at the destination. The SA wont sap your main tank like trying that with a 19 or 40.

Deep VI
10-30-2008, 20:21
My pesonal set up is a 19cf mounted inverted to a Quick Draw pony bracket from ST. I have the reg clipped to the bottle and a rubber band keeping the hose tucked against the tank. The reg sits right where my hand naturally rests when I reach behind my back. This leaves the whole rig one piece to make changing tanks or handing off the bottle a snap. Personally I think 19cf is enough for rec limits. Anything bigger than that and it might become a hassle and you might not take it. I've accended from 110' did a 3min safety stop and still had about 500lbs left.

in_cavediver
10-30-2008, 21:36
Obviously, I'd much rather sell someone a pony bottle, another reg, gauge, pony attachments, etc - than a spare air. It will cost much more! But that being said - I have taken a 1.7 spare air from 100 feet to the surface. And when I travel - these days, carrying an extra 30 lbs of gear is pretty much impossible - so I do carry a small spare air with me. I'd much rather have a few cubic feet of air with me than 30 cubic feet in my closet. And I know, have tested that it is enough air to get me up to the surface.

In a real emergency, will I breathe harder?? Sure - but I'll probably swim faster too. Will I have enough air to do a deco stop? Probably not - but people recover from the bends... drowning... not so much. Would I rather have 19, or 30, or 40, or 80 or 120 cubic feet of extra air... sure.... but it's not practical for the traveling and diving I do.

Just another take on it...

If you know and understand its limitations, then its just another piece of gear. I do clearly see your point traveling and that goes well with the point I made about carrying it. Small makes it convenient and convenient means it likely will be with you if you need it. With that, given the choice of something or nothing, I'll always take something, even if its only an aid to a CESA.

I am reminded of what one of my Cave instructors told me. In diving, air is life. If you have air, you can solve pretty much everything else.

emcbride81
10-30-2008, 21:47
[quote=ScubaToys Larry;240415]

I am reminded of what one of my Cave instructors told me. In diving, air is life. If you have air, you can solve pretty much everything else.


wise words right there!

ScubaToys Larry
10-30-2008, 22:04
.

Are there any restrictions on carrying Spare Air in luggage like there are for cylinders?

You simply remove the reg (which you can by hand) and pack it in your luggage... that's it!

ScubaDude
10-30-2008, 23:51
Do a search for spair air, spair death etc and you'll get more than you ever wanted.

That said, here is a fairly honest appraisel of the equipment.

--- Observations -------
Before looking at a pony or spair air, look up gas management, rock bottom and understand quantitatively how air is used. IE - Surface consumption rates and how depth changes it. Once you see that, we can talk about Surface rates in cft/min. Mine is around .5cfm/min on average.

Now, lets talk depths. Spair air is rec so lets say our dive is to 100ft or 4 atms of pressure. 130ft is 5atm, 66ft is 3atm and 33ft is 2atm.

Now, this is the biggie. If a diver goes OOA, they will be stressed. When stressed, air consumption goes up 50-150% or 1.5x-2.5x the original. For me, I simply double my surface rate. This lasts between 1 and 2 minutes after getting on additional air before returning to normal. I plan for 2 minutes.

----- planning -------

Assume at 100', within NDL etc and go OOA with spair air. At this depth, my normal air consumption rate is around 2cft/min. By going OOA, I am not at around 4cft/min. With spair air, I cannot stay on the bottom 1 full minute. I need to start ascending immediately. If I go from 100ft to 33ft in 30sec, (average depth of 66ft and holding 120-130ft/min ascent rate) I will use 3cft of air and exhaust the spair air and go OOA again.

Do the same for a dive to 66ft. I go OOA and my consumption rate goes to 3cft/min at depth. My ascent will take 1 min @ 60ft/min and use 2cft. I can stay on the bottom at most 20 seconds to make it to the surface.

Now, using a 19cft pony:

100ft OOA - goto pony and stay at depth 2 minutes getting my buddy etc. I used 8cft of air doing that. I then do a standard ascent to 20ft @ 30ft/min. It should take 2.5 minutes with an average depth of 60ft (about 3atm) In this I used around 4cft. I still have 7cft in my pony to do a safety stop. I burn 0.8cft/min of air at 20ft so I can do 3-4 minutes if I want to. The final ascent should take 0.5 - 1cft of air.

------------ more observations -----------------------
From the above situations, you can clearly see the limitations. Spair air is a CESA aid and nothing more. Depending on the depth, you may go OOA again before reaching the surface.

Comparing that to a pony is simple, all it boils down to is the cft of the tank. A 13cft tank which is a small pony, offers a larger delay time and margin for error for roughly the same cost as spair air (so is the 19).

Now, one thing spair air is really good for is this. Its very small and its likely that you'd carry it and have it to use. A bigger pony is just that, bigger. It's one of those questions of whether you'd really carry it. It does no good on the boat.

----------------- My Biases ------------------

At this point, I am beyond a pony. If I think I need a pony, I am taking true redundant air and if solo, a buddy bottle. (full 1/3rd of my bottom gas or more). If you are doing deep rec dives - IE 70ft or deeper, a pony is a good idea. 70ft is the depth where I personally decide I need redundant gas.

Spair air does have its place but its not with scuba divers.

Very good piece of info, but I'm not so sure that Chirodoc is gonna grasp it.

Hopefully he has focused on your conclusion of Spare Air and it's usefullness.

Largo
10-31-2008, 19:39
Larry,
Thank you! I don't see what is so bad about spare-air. I've gotten into free-diving lately, and I'm down to 50 feet (no big deal for some of the guys on this site). But, if I can swim down to 50' and then back up with one breath of surface air, then I figure a spare air would get me comfortably to the surface from 100'.

Please, no flaming about the safety stop. It's just a precaution.

OH-JJ
11-01-2008, 17:00
Yes the spare air will give you maybe a minute or so extra air. and that's it.

I only have one problem with in_cavediver's post and that is while some experienced divers have SAC rates of .5 and lower the Average diver will be closer to .6- .8 and for new divers 1.0 is not usual. Which makes it even worse than what is described.

I now dive mostly doubles. I also Sling a 40, if I am not doing Deco, I have it as a pony bottle. But I also have my 19cf that I used before.

I am now debating on leaving my 19 in FL with Family for when I dive there. I already have a AL80 that I keep there, So that when I fly down instead of driving, I Know I have good tanks there.

Defman
11-01-2008, 18:54
Obviously, I'd much rather sell someone a pony bottle, another reg, gauge, pony attachments, etc - than a spare air. It will cost much more! But that being said - I have taken a 1.7 spare air from 100 feet to the surface. And when I travel - these days, carrying an extra 30 lbs of gear is pretty much impossible - so I do carry a small spare air with me. I'd much rather have a few cubic feet of air with me than 30 cubic feet in my closet. And I know, have tested that it is enough air to get me up to the surface.

In a real emergency, will I breathe harder?? Sure - but I'll probably swim faster too. Will I have enough air to do a deco stop? Probably not - but people recover from the bends... drowning... not so much. Would I rather have 19, or 30, or 40, or 80 or 120 cubic feet of extra air... sure.... but it's not practical for the traveling and diving I do.

Just another take on it...




Ditto. I don't dive solo/alone, but I don't dive with a buddy either and I sometimes wander away from the group. Do I need enough air to get to the surface? Not really, but I do need enough air to get me back to the group so I can share with the DM and do a safe accent. To that end, I'm seriously looking at the Zeagle Pony Bottle kit. It'll probably get me to the surface in a pinch.


Edit: Hehe, this was my Devil Post, 666 :smiley15:

OH-JJ
11-01-2008, 22:53
Obviously, I'd much rather sell someone a pony bottle, another reg, gauge, pony attachments, etc - than a spare air. It will cost much more! But that being said - I have taken a 1.7 spare air from 100 feet to the surface. And when I travel - these days, carrying an extra 30 lbs of gear is pretty much impossible - so I do carry a small spare air with me. I'd much rather have a few cubic feet of air with me than 30 cubic feet in my closet. And I know, have tested that it is enough air to get me up to the surface.

In a real emergency, will I breathe harder?? Sure - but I'll probably swim faster too. Will I have enough air to do a deco stop? Probably not - but people recover from the bends... drowning... not so much. Would I rather have 19, or 30, or 40, or 80 or 120 cubic feet of extra air... sure.... but it's not practical for the traveling and diving I do.

Just another take on it...




Ditto. I don't dive solo/alone, but I don't dive with a buddy either and I sometimes wander away from the group. Do I need enough air to get to the surface? Not really, but I do need enough air to get me back to the group so I can share with the DM and do a safe accent. To that end, I'm seriously looking at the Zeagle Pony Bottle kit. It'll probably get me to the surface in a pinch.


Edit: Hehe, this was my Devil Post, 666 :smiley15:

So you are sure that you can always be a minute away from the group? are you always with a DM?

When the SHTF, which is safer, depending on someone else being within one minute of you when you are swimming hard, or having enough gas to safely reach the surface?

I have been on many Drift dives when we have gotten spread out. some one looks in a hole, or under a ledge, or gets in flow with a different speed.
it happens.
Then you better know your gas, and not have a loss of gas failure.

Defman
11-02-2008, 06:21
So you are sure that you can always be a minute away from the group?

Yes. And I'm sure a 6cf tank is going to last significantly longer than 1 min.


are you always with a DM?

Yes.

in_cavediver
11-02-2008, 09:54
So you are sure that you can always be a minute away from the group?

Yes. And I'm sure a 6cf tank is going to last significantly longer than 1 min.


Not to nitpick - but do the math. It might be shorter than you think. Also realize you can't breathe the tank to zero. I figure 150psi is the limit which is 5% of a 3000psi tank. See my post earlier for a much clearer explanation of gas use. For me, a 1.7cft spare aid would last, stressed with a sac of 1.0cft/min which double my normal sac, at 66ft (3atm), around 30 seconds. The 3cft model would hit around a minute. Your 6cft model is only 2 minutes - not what I would call 'significantly more'. If you go to 100ft, you won't even make 2 minutes with that 6cft system.

That said - we are discussing gear. Gear is designed to fill a specific need, the questions to ask are what need am I filling, does this choice meet it and is there a better choice.

Spare air does have one very big undeniable advantage and that is size. Its small and likely to be with you. It also only really fills the need of a CESA aid. Its not really a redundant air source in my opinion due to its very low capacity. It will give you some breaths but you need to get moving and start the CESA or you'll be OOA again. Redundant air to me allows you to complete the dive in a controlled manner, with your buddy and doing and safety stops along the way. Spare Air can't do that.

To each they own. I only hope divers understand the limitations of their equipment, be it spare air, pony, doubles or whatnot. Everything is a trade off.

Wetnurse28
11-02-2008, 13:23
Cave Diver,

You seem to have vast knowledge,

So I plan at this point to make no deeper dives that the rec. limit

Would a 19 work or should I go with 30?
Keep in mind that I plan to wear the pony on ever single dive

CompuDude
11-02-2008, 16:10
So you are sure that you can always be a minute away from the group?

Yes. And I'm sure a 6cf tank is going to last significantly longer than 1 min.


are you always with a DM?

Yes.

That depends entirely on your depth, and what your stressed SAC is. Even those with the best stressed SAC rates are going to be not much longer than a minute once you get to the 100' and lower range.

in_cavediver
11-02-2008, 19:44
Cave Diver,

You seem to have vast knowledge,

So I plan at this point to make no deeper dives that the rec. limit

Would a 19 work or should I go with 30?
Keep in mind that I plan to wear the pony on ever single dive

I could say many things but the best answer is to let you figure it out yourself. (I'll tell you how though). Either would likely work just fine for you. One thing to consider is size. Below is the synopsis on pure theoretical gas requirements but if the thing is too big, you won't carry it. Make sure it is something you would carry.

Capacity Planning:
Step 1 - get your surface air consumption rate. If you don't know how, I can post a few methods.

Step 2 - Determine your max depth. You have stated rec limits so its 130ft or 5atms of pressure. You could limit this to 100ft or 4atms its all up to you and how you dive.

Step 3 - Determine you ascent profile. I like to plan to have a couple minutes at depth to get with my buddy, sort things out and start my ascent on my terms. I also like 30ft/min but some use 60ft/min. I also like to plan for a stop @20ft for 3 minutes or so. This could be omitted, moved to 15ft or lenghtened. Again, this is how you want to dive, not me.

Step 4 - Put it all together to figure out how much air you really need to do what you want.

Example:
SAC rate is 0.75 which is a decent estimate. It may be on the high side.

Max depth is 130ft so 5atm.

We assume our SAC doubles due to stress for 2 minutes when we change over to the pony.

Now, how much air and when

Depth, 130ft (5atm) - 2 minutes. SAC is 0.75, doubled for stress and mulplipled due to depth. 0.75 * 2 * 5 or 7.5cft/min. We are here 2 minutes so we use 15cft.

Ascent to 20ft. This is a two part process. First we figure out the time. We are going up 110ft at 30ft/min so it takes almost 4 minutes. The second part we need is the average depth. Its easy, just the average of 130 and 20 or 75ft (3.3atm). We then use our SAC to figure air consumed. 0.75cft/min * 3.3atm = 2.5cft/min For the 4 minute ascent, we'd use 10cft.

Stop @ 20ft. Consumtion rate = 0.75*1.6 = 1.2cft/min. We stay 3 minutes which means we use around 4cft.

Ascent to the surface. We can calculate this as well a good rule of thumb is 1-2 cft.

So we do we have on the very conservitive ascent from 130: 15+10+4+2 or 31cft. This is also with a little padded numbers from rounding.

Repeated for 100ft max depth:
100: 12+7+4+2=25cft

Repeated at 130cft with my SAC 0.5cft/min:
130: 10+7+3+1 = 21cft

In real life, you would adjust on the fly what your profile would look like based on the gas you had. You likely wouldn't stay at depth the full 2 minutes, your SAC may not double for 2 minutes and you likely would go faster than 30ft/min. This is a worst case type of planning. If you say 1 min at depth rather than 2, 60ft/min rathen than 30ft/min then your needs for the 130ft dive with a SAC of 0.75 is only 18cft or so.

Its all in how you want to ascend and surface.

texdiveguy
11-02-2008, 20:02
Wetnurse28...... consider the info. layed out by in-cave above, solid data.

If I were doing this all over knowing what I know today and knowing the popularity of the resale option an Al40 has in the market I would go that route (plenty of contingency gas for rec. diving//opt. for tech deco bottle//great resale item). BUT-- at the minimum and still a good choice is an Al19.....for a good diver in most o/w setting were a pony is needed it can fill the bill. They are also popular as a resale item if later you want to. My persl. recreational pony is a 19cf slung bottle, I also have never had to use it in an OOG situation :) ,,,, so plan your gas needs and stick to your pre-planned dive profile.

ScubaDude
11-02-2008, 20:03
Cave Diver,

You seem to have vast knowledge,

So I plan at this point to make no deeper dives that the rec. limit

Would a 19 work or should I go with 30?
Keep in mind that I plan to wear the pony on ever single dive

I could say many things but the best answer is to let you figure it out yourself. (I'll tell you how though). Either would likely work just fine for you. One thing to consider is size. Below is the synopsis on pure theoretical gas requirements but if the thing is too big, you won't carry it. Make sure it is something you would carry.

Capacity Planning:
Step 1 - get your surface air consumption rate. If you don't know how, I can post a few methods.

Step 2 - Determine your max depth. You have stated rec limits so its 130ft or 5atms of pressure. You could limit this to 100ft or 4atms its all up to you and how you dive.

Step 3 - Determine you ascent profile. I like to plan to have a couple minutes at depth to get with my buddy, sort things out and start my ascent on my terms. I also like 30ft/min but some use 60ft/min. I also like to plan for a stop @20ft for 3 minutes or so. This could be omitted, moved to 15ft or lenghtened. Again, this is how you want to dive, not me.

Step 4 - Put it all together to figure out how much air you really need to do what you want.

Example:
SAC rate is 0.75 which is a decent estimate. It may be on the high side.

Max depth is 130ft so 5atm.

We assume our SAC doubles due to stress for 2 minutes when we change over to the pony.

Now, how much air and when

Depth, 130ft (5atm) - 2 minutes. SAC is 0.75, doubled for stress and mulplipled due to depth. 0.75 * 2 * 5 or 7.5cft/min. We are here 2 minutes so we use 15cft.

Ascent to 20ft. This is a two part process. First we figure out the time. We are going up 110ft at 30ft/min so it takes almost 4 minutes. The second part we need is the average depth. Its easy, just the average of 130 and 20 or 75ft (3.3atm). We then use our SAC to figure air consumed. 0.75cft/min * 3.3atm = 2.5cft/min For the 4 minute ascent, we'd use 10cft.

Stop @ 20ft. Consumtion rate = 0.75*1.6 = 1.2cft/min. We stay 3 minutes which means we use around 4cft.

Ascent to the surface. We can calculate this as well a good rule of thumb is 1-2 cft.

So we do we have on the very conservitive ascent from 130: 15+10+4+2 or 31cft. This is also with a little padded numbers from rounding.

Repeated for 100ft max depth:
100: 12+7+4+2=25cft

Repeated at 130cft with my SAC 0.5cft/min:
130: 10+7+3+1 = 21cft

In real life, you would adjust on the fly what your profile would look like based on the gas you had. You likely wouldn't stay at depth the full 2 minutes, your SAC may not double for 2 minutes and you likely would go faster than 30ft/min. This is a worst case type of planning. If you say 1 min at depth rather than 2, 60ft/min rathen than 30ft/min then your needs for the 130ft dive with a SAC of 0.75 is only 18cft or so.

Its all in how you want to ascend and surface.

In_cavediver,

Although I understand the gas consumption rates that you have posted, where did you learn this? Advanced Decompression Course?

FishFood
11-02-2008, 20:22
LOL!

The OP didn't even ask which was better...

This is good :smilie39:

OH-JJ
11-02-2008, 21:43
Wetnurse28...... consider the info. layed out by in-cave above, solid data.

If I were doing this all over knowing what I know today and knowing the popularity of the resale option an Al40 has in the market I would go that route (plenty of contingency gas for rec. diving//opt. for tech deco bottle//great resale item). BUT-- at the minimum and still a good choice is an Al19.....for a good diver in most o/w setting were a pony is needed it can fill the bill. They are also popular as a resale item if later you want to. My persl. recreational pony is a 19cf slung bottle, I also have never had to use it in an OOG situation :) ,,,, so plan your gas needs and stick to your pre-planned dive profile.

I'd second the AL40. the cost is not that different. and when rig it as a stag bottle and sling it. Underwater, you really don't notice it is there.
As an added bonus, it is easy to handle on multi tank dives, as opposed to the clamps that attach to your tank or cam band.
I would recommend that you set yours up just like a stage / deco bottle. complete with the 6 inch hp hose and 2 inch brass and glass SPG. this is much easier to read than the little button gauges.

in_cavediver
11-03-2008, 05:12
In_cavediver,

Although I understand the gas consumption rates that you have posted, where did you learn this? Advanced Decompression Course?

To be honest, I don't know if I could pin it to a specific class. Probably a combination of Advanced Nitrox, Trimix and Cave classes plus some online reads about Rock Bottom gas planning.

Personally, I think its a crime this concept isn't introduced at the OW level. Its really not that hard to understand and you don't have to delve into the details like I did to be useful.

Jack Hammer
11-03-2008, 09:03
Cave Diver,

You seem to have vast knowledge,

So I plan at this point to make no deeper dives that the rec. limit

Would a 19 work or should I go with 30?
Keep in mind that I plan to wear the pony on ever single dive

Perhaps you should ask yourself which size bottle you are likely to actually carry on each and every dive. As mentioned, a smaller sized pony that you actually take with you does more good than a larger sized pony sitting topside on the boat.

Try asking other divers you know what they have and see if someone can let you dive with different sized ponies to see what you're willing to carry on everydive.

Jack

Jack Hammer
11-03-2008, 09:35
Just remembered, another way you can get an idea on your next dive of how much air is availible in the different pony tanks compared to an AL80. I rounded the numbers off to make it easier.

1.7cf is 66psi used in an AL80
3cf is a little over 100psi used in an AL80
6cf is a little over 225psi used in an AL80
13cf is about 500psi used in an AL80
19cf is about 750psi used in an AL80
30cf is a little over 1150psi used in an AL80
40cf is 1550 psi used in an AL80

Watch your spg and you can get an idea of how fast you can go through each of those amounts (then double those, at minimum, to get an idea of how long it'll last if you're stressed).

Jack
**extra info pertaining to AL80 tank: capacity=77.4cf@3000psi. 1 psi=0.0258cf. 1cf=38.76psi.

russp
11-03-2008, 11:44
I've been giving this some thought for a while. I'm just looking for something to get me out of a bind if I have a regulator failure or am dumb enough to run out of air. I prefer to be my own buddy rather than rely on someone else. I've been looking at the 3cf Spare Air and the 6cf H2Odyssey setup; just something easy to carry and get to.

texdiveguy
11-03-2008, 12:16
I've been giving this some thought for a while. I'm just looking for something to get me out of a bind if I have a regulator failure or am dumb enough to run out of air. I prefer to be my own buddy rather than rely on someone else. I've been looking at the 3cf Spare Air and the 6cf H2Odyssey setup; just something easy to carry and get to.

Russ....neither really offer much benefit IMHO....but if you are only going to dive CSSP than either will work better than a CESA.

huvrr
11-03-2008, 18:35
Yesterday I had to switch to my 19 cu ft pony at 82 feet when my reg freeflowed. We headed up to 40ft then 25ft and restored my primary there. I used 1800psi in those 7 or eight minutes. People sometimes poke fun at me for carrying it on buddy dives but, personally I feel naked without it.

texdiveguy
11-03-2008, 20:07
Yesterday I had to switch to my 19 cu ft pony at 82 feet when my reg freeflowed. We headed up to 40ft then 25ft and restored my primary there. I used 1800psi in those 7 or eight minutes. People sometimes poke fun at me for carrying it on buddy dives but, personally I feel naked without it.

Contingency gas bottles rock!

bsktcase93
11-06-2008, 23:12
I had a spare air. Shortly after I bought it, I sold it.. and bought a 30 cf pony and a used basic reg. All togather it was only a little more for the pony. If your trying to make a choice I wouold advise a pony of any size ( just not 3 cf).

As for "where does the pony go" It can be mounted to your main trank with the reg cliped to your bc. or you can sling it to your bc in the front. Some bc's (like mine) can not accomedate that. So I mount it to my tank.

I hoped that helped.


thanks duckydiver you really helped me make up my mind. im going for the 30cf pony

russp
11-07-2008, 13:32
Yesterday I had to switch to my 19 cu ft pony at 82 feet when my reg freeflowed. We headed up to 40ft then 25ft and restored my primary there. I used 1800psi in those 7 or eight minutes. People sometimes poke fun at me for carrying it on buddy dives but, personally I feel naked without it.

If I'm doing the math correctly, you used about 10 or 11 cu ft of air then; this was making two stops trying to correct the problem. If someone is just wanting to make the surface with some air to breathe; even from 100', it seems maybe a 9 cu ft would do the trick. I'm not talking anything extreme like running out of air while getting untangled from fishing line, just making the surface after a reg failure or OOA situation.

OH-JJ
11-07-2008, 17:23
Yesterday I had to switch to my 19 cu ft pony at 82 feet when my reg freeflowed. We headed up to 40ft then 25ft and restored my primary there. I used 1800psi in those 7 or eight minutes. People sometimes poke fun at me for carrying it on buddy dives but, personally I feel naked without it.

If I'm doing the math correctly, you used about 10 or 11 cu ft of air then; this was making two stops trying to correct the problem. If someone is just wanting to make the surface with some air to breathe; even from 100', it seems maybe a 9 cu ft would do the trick. I'm not talking anything extreme like running out of air while getting untangled from fishing line, just making the surface after a reg failure or OOA situation.

you know to me it does not matter if I am designing Computer systems that handles millions of dollars an hour, or things that can kill me....
I am A firm Believer that Murphy was an optimist!

Fireplug
11-09-2008, 10:11
I just did 4 dives with the new love of my diving life, a 120 CF STEEL NITROX tank. I am 5' 9" and 260 lbs, non-smoker, fairly good shape but fat. I am usually one of the first back on the boat but now with a 120, WOW!! 47 minutes and still had 1100 psi left. I usually wear 16 lbs. with a 80 AL so went down to 6 lbs with the 120 steel. I was just a little light on my safety stop so will need to keep tuning on that. I realize the larger tank does weigh more, someone said 47 lbs., but what the hay, it's on your back and once you're in the water, you don't feel any difference. Be interested to know what the weight difference is between a single steel 120 and 80 doubles.
Coupled with my new Compumask and I'm feeling lots more comfortable in the water and hate to get back on the boat.
I'm definitly starting to shop around for a bigger tank. Just the relaxing feeling of having lots of gas on my back is worth a few bucks!!!

fisheater
11-09-2008, 20:04
Love my 120, too.

Jack Hammer
11-10-2008, 12:56
Half the reason to carry a pony tank is the extra air if you go OOA. The other half is redundant gas and regulator if you have an issue with your main rig. Carrying a larger capacity tank only helps if you to lessen the chance of running OOA as early, it does little, other than buy you more time, if you have an o-ring go, hose blow, freeflow or some sort of reg malfunction, etc.

FTR, I saw a diver run his 120 tank dry on the same dive I was using an AL80, I had plenty left. The extra capacity is nice, just be aware that there is no definitive answer for all dives and divers when considering your options.

Jack

sabbath999
11-18-2008, 12:04
Love my 120, too.

I got an AL80 as a starter tank, I am wondering if I should move up to a 120 as well.

I am a big guy (6'3, 275) but very fit aerobically (I cycle 30 miles a day on average, or spend 2 hours a day on the cycling trainer in the winter) and I use a lot of air. I am also a NOOB which means I am an unskilled air hog.

My wife uses an AL63, she is a 5'4 uber-fit 115 pound performance cyclist and uses... ummm... NO air. She can go at 30 feet for an hour and come back with 1500 pounds left in her AL63... I usually call the dive at 1100 and use the rest of my air in shallow depths (5-10 feet) doing skills like hovering and buoyancy control until my gas is down to 500. Heaven help me if I get a short fill.

I have about 24 LB's of weight on (cold water, thick suit)... I am thinking a 120 (and learning how to not be such a stinkin air hog by increasing my breathing and gas management skills through experience and training) might be my answer... I just hate calling a dive when she has 1500+ left.

James1010
11-18-2008, 12:09
All the pony bottles is, is for spare air for emergencies. I am pretty sure that it is diver prefference to where it is positioned on the diver. Most dive masters who take out discovery divers will carry those also some cave divers will use them also.

in_cavediver
11-18-2008, 19:31
.....will carry those also some cave divers will use them also.

In tec diving circles, these are either Deco bottles, stage bottles or buddy bottles. The distinction is based on the intended use. A stage is bottom gas planned to be used during the dive, a buddy bottle is 1/3rd or so of your planned bottom gas to be used only in an emergency. Deco bottles have mixes other than your bottom gas.

I only say this because for me, a 'pony' used as a buddy bottle is an AL80.

Splitlip
11-18-2008, 20:13
Half the reason to carry a pony tank is the extra air if you go OOA. Jack

Respectfully, disagree.

Don't want to go scubaboard on you, but they are not for going out of air.
The other half of your answere is correct. An equpment failure if no buddy is available.
OOG should never happen if one plans a little and dives heads up.

IMHO, a diver who goes OOG w/o some kind of equipment failure probably will not be on the ball enough to bring his back up on line.

Grin
11-19-2008, 07:39
The bouyancy factor of a AL 80 vs a Steel 120 goes something like this.
A empty AL80 is about 4 lbs positive bouyant.
A empty steel 120 is about 2 lbs negative.
So when going from a single AL 80 settup to your new single steel tank you should be able to remove about 6 lbs of weight.

I can do an hour + at 70-80 ft on a HP120 (normally do about 50 minutes). I have 4 of them and lots of air is nice. I still wear a pony for bail possibilities. I use a 13cf to about 100 ft. I just aquired a 19cf, for free, so now I have that for up to around 130ft. I also have a 30cf for the deep stuff(used to be for 120+, but now I have the 19 in the mix).

Jack Hammer
11-19-2008, 11:03
Half the reason to carry a pony tank is the extra air if you go OOA. Jack

Respectfully, disagree.

Don't want to go scubaboard on you, but they are not for going out of air.
The other half of your answere is correct. An equpment failure if no buddy is available.
OOG should never happen if one plans a little and dives heads up.

IMHO, a diver who goes OOG w/o some kind of equipment failure probably will not be on the ball enough to bring his back up on line.
No offense taken, most of the reasons I've personally heard people asking about using a pony tank is "for a backup in case I run out of air." The intended proper usage of them becomes less rellevant to the discussion if people are buying them simply in case they "run out of air," and don't really consider the reallity of equipment failure as applying to them. I was just trying to word it in a non-SB way instead of saying something along the lines of "for people to stupid to properly monitor their gas supply..."

As far as OOG should never happen, I couldn't agree more, however it does. And unfortuneately it seems to happen far too frequently. I think better training and not diving beyond your training/abilities is a better solution for people than just strapping on some extra air. But if strapping on some extra air saves lifes, then I'd rather have a few live idiots around than a bunch of dead divers.

Jack:smiley20:

Mitch200
01-23-2009, 16:39
Any opinions on the Zeagle quick deploy pony systems - 6 and 20 cubic foot models?

CompuDude
01-23-2009, 17:29
Any opinions on the Zeagle quick deploy pony systems - 6 and 20 cubic foot models?

All of the arguments against the Spare Air can apply to the 6cf Zeagle unit as well. It's just too dang small to be worth much. 20cf is certainly an adequate size for a pony, in most circumstances, and Zeagle is a respectable company, so if you must carry a pony, I suppose that would work. I'd still be inclined to prefer a standard pony, slung, however.

RoyN
01-23-2009, 18:00
I use the 6cuft pony by Zeagle as my inflation bottle. I think thats about as good as it gets, as for tanks being carried, I'm with CompuDude on this, slung is the alot easier for me. Saw someone on the boat carrying the a pony that is connected to their main tank and it was a big BIG hassle especially the guy took too much room in order to get his gear together. Just my 2 cents opinion.

Black-Gorrilla
01-26-2009, 13:54
That goes more for personal opinion rather than how it actually works... (the pony on the main tank that is)
I know people that do it like that, and it stays out of the way, but if needed is easy to reach and use... just a matter of having space on a boat for it or not.
I like the "slung" 30 or 40cf bottle... but it gets in the way of spearing and lobstering etc... so it's more about how convenient it is on the situation your gonna be in.

kjvander
01-26-2009, 14:31
i don't know what you guys are talking about....don't you remember Baywatch....they could swim for hours on a spare air....and everything you see on tv is real.....

chicken
01-26-2009, 16:25
That was real? I knew it.

kjvander
01-26-2009, 17:21
yes....there is no way that anyone can not tell me that hasselhoff can't swim underwater on a spare air for at least 15 min while doing tasks....it's just unpossible.

RoyN
01-27-2009, 16:59
That was real? I knew it.

Well, the lifeguard's boobs were real. :smiley20:

Rainer
01-27-2009, 17:02
Well, the lifeguard's boobs were real. :smiley20:

Really expensive.

kjvander
01-28-2009, 07:26
they were almost like real PFD's....but i don't know the bouyancy characteristics of silicone or saline....

UCFKnightDiver
01-28-2009, 08:59
Double Spare Airs they're awesome!!!! :D

navyhmc
01-28-2009, 17:06
Well, silicone is heavier than water, saline is neurtal-no floatation bennies from either. (saw this on Mansers.)