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TRACI
09-12-2007, 13:37
I really like the idea of having a pony tank instead of spare air, What is the best size pony tank for recreational warm water diving? I generally never dive over 100 ft, I am still relativly a new diver.

GONEHAWKN
09-12-2007, 14:48
this will open all kinds of answers which all will feel is the right answer. me personally, i use a 30cf pony which i sling on my right side.

GONEHAWKN
09-12-2007, 14:49
you might also want to check out this thread:

http://forum.scubatoys.com/showthread.php?t=675

TRACI
09-12-2007, 15:00
Thanks for the info, attaching to my tank or sling was going to be my next question. Too many decisions!

CompuDude
09-12-2007, 15:04
You can go as small as 19cf, but I think 30 is probably the sweet spot. If you think you may ever go down the technical route, save some money just buy a 40cf tank.

In either case, slinging it to the left if probably one of the better carrying options.

Of course, most of these points were covered in the thread linked above, so this is redundant if you read that already...

fire diver
09-12-2007, 15:05
In order to correctly answer your question, you need to know what you SAC rate is. That number is used to compute gas needs to SAFELY ascend from depth. Without it, it's nothing but a guess as to what you need.

FD

Capt Hook
09-12-2007, 15:19
As stated previously a 19 or 30 is best for most recreational dives.Stay away from the Spare Air.

wxboy911
09-12-2007, 15:24
I have a 30cf pony-19 did not have enough air and the 40 was physically bigger than I wanted to go...although it would have worked OK.

Hollywood703
09-12-2007, 17:15
I agree with a 30cf, not how you carry it is personal preference...I have mine mounted on my tank.....

subsur
09-12-2007, 19:20
from 19 to 40 cuft as many folks pointed out. depends on your diving environment, skills, equipment.

meesier42
09-12-2007, 19:50
wow you can go with anything that you want. technically, if you stay within your recreational dive limits you always have the option to do an emergency free swimming ascent and you don't even NEED a pony bottle

CompuDude
09-12-2007, 20:06
wow you can go with anything that you want. technically, if you stay within your recreational dive limits you always have the option to do an emergency free swimming ascent and you don't even NEED a pony bottle

So you think it's a good idea to have "do a CESA" as your backup plan should the proverb hit the spinny thing at 100'?

fire diver
09-13-2007, 08:15
I have seen a lot of members here saying what size pony they carry. I'm always in favor of redundency, safety and redundency. But how many of you that carry a pony, have actually done the math? Can that tank get you up from depth, not exceeding 30ft/min with a safety stop?

FD

fire diver
09-13-2007, 08:19
wow you can go with anything that you want. technically, if you stay within your recreational dive limits you always have the option to do an emergency free swimming ascent and you don't even NEED a pony bottle

The entire premise of carrying a pony is that you WON'T have to do a CESA. CESA may keep you alive, but may get you bent. They are an absolute last resort that I should never have to perform since I carry an alternate air source.

FD

mwhities
09-13-2007, 08:19
I dive al100s and I have a al40 slung (now). I don't dive deeper than 100' right now and I'll still carry th al40 with me. Why? I might need it or someone else might. My al100 is just big enough for me. Not me and someone else. ;)

Michael

K-Valve
09-13-2007, 12:34
As stated previously a 19 or 30 is best for most recreational dives. Stay away from the Spare Air.


In order to correctly answer your question, you need to know what you SAC rate is. That number is used to compute gas needs to SAFELY ascend from depth. Without it, it's nothing but a guess as to what you need.

Most divers can find the surface safely from 100' with a 19cf pony, using a 30cf pony is super conservative if you never go deeper than 100'.

There are several factors you'll want to consider if you really want to figure out what size pony you'll need to make it back from 100' safely though. It's not as simple as it seems at first glace, but it is worth the effort.

First, you should heed Fire Diver's advice and find out what your true SAC rate is. This is going to be different from what your computer tells you because your true SAC rate is your average air consumption per minute, at sea level, at rest. Obviously, when you're diving you're not resting or at sea level, and your computer calculates it for your average overall depth.

To determine your true SAC rate grab your tank, reg & gauges, and mask. Note the starting psi in the tank. Next, make yourself comfortable, and turn on the TV or grab something else to do or read. Put your mask on so you're not breathing through your nose, and skewing the results, then start breathing through the reg. Continue breathing normally off the reg for ten minutes non-stop. Note the ending psi in the tank.

Now comes a little math. Use the following formula to figure out your SAC rate (e.g. how many cf of air you normally breath at the surface per minute): ((PSI used * (Tank volume rating / Tank pressure rating)) / 10 minutes).

As an example, let's say you're using a standard aluminum 80 tank. The total tank volume is actually 77.4 cf and the pressure rating is 3000 psi. Let's also say you used 250 psi while breathing normally from the tank for 10 minutes. Your equation would look like this:
((250 * (77.4 / 3000)) / 10)

Which breaks down like this:
77.4 / 3000 = 0.0258 cf/psi
250 * 0.0258 = 6.45 cf used in 10 minutes
6.45 / 10 = .645 (your SAC rate or cf used per minute)

So, in this example the numbers are pretty average and you'd be breathing .645 cf of gas per minute at the surface, at rest.

Now figure you are at 100' and things go sideways. How many cf of air will you need to surface at a safe rate of ascent of 30'/minute and include a minimum 3 minute safety stop?

From 100' it will take you just over 6 minutes to ascend and conduct your safety stop. For the first minute you'll be breathing at approximately 4 atmospheres of pressure so you'll use 2.58 cf of air (.645 cf * 4). For the second minute you'll breath at approx. 3 atm so you'll use 1.935 cf of air. For the last minute of your ascent you'll use another 1.29 cf of air during your ascent and 2.9025 cf during a safety stop of 3 minutes at 15'. That's a total of just over 8.7 cf of air, which we'll round up to 9 cf.

Of course, your SAC rate was determined while you were calm and at rest. Since you have to work a little to get to the surface and you are probably a little stressed from the surprise out of air situation with your primary tank/reg you'll need more air than your SAC rate suggests. So, to be conservative let's add about a 50% increase to your SAC rate and call it 1.0, or 1 cf of gas used per minute at the surface. When you do the same calculations with that number you'll use about 14 cf of air to surface safely. That totally rules out a spare air of any size and it's cutting it too close for a 13 cf pony as you probably ought to add 4 or 5 cf of contingency air in case you get lost, disoriented, etc.

All said, an average diver can make it to the surface safely from 100' with a 19 cf pony bottle. Unless someone really gets themselves into a jam, 30 cf is overkill at a max depth of 100'.

However, you should calculate your own SAC rate and plug in your numbers to figure out what size pony you really need.

Dive Safe!!

CompuDude
09-13-2007, 12:36
I have seen a lot of members here saying what size pony they carry. I'm always in favor of redundency, safety and redundency. But how many of you that carry a pony, have actually done the math? Can that tank get you up from depth, not exceeding 30ft/min with a safety stop?

FD

I don't carry a pony, I dive doubles instead. But a 19cf pony will get most people to the surface at a safe rate (with safety stop) from any reasonable depth. A 30cf pony might just get two people up. Might.

Figure RMVs in the 1.0cf/m range due to stress... note I have seen stressed RMVs closer to 1.5cf/m, however, which would change these numbers quite a bit!

100 fsw starting depth (4 ATA)
Average depth during direct ascent is 50 fsw, or ~2.5 ATA)
Ascent is 30 fpm. (3.3 min total ascent time)
3 min safety stop at 15' (.45 ATA)

Generally prudent to factor in at least one minute at depth to resolve issue (deploy pony, share air, whatever).

4.0 ATA x 1.0cf/m = 4.0cf/m x 1.0 min = 4.0 cf needed to resolve issue within 1 minute at depth

2.5 ATA x 1.0cf/m = 2.5cf/m x 3.3 min = 8.25 cf needed for trip from 100'.

.45 ATA x 1.0cf/m = .45cf/m x 3 min = 1.35 cf needed for safety stop.

Total air needed thus far: 13.6 cf. ZERO margin for error, here, of course... especially if you end up so stressed you exceed 1.0 cf/m.

It's pretty clear the 19cf pony recommendation is an acceptable working minimum for most people. A 30cf pony, however, might just get both you and your buddy up safely... or give you extra cushion against longer time to resolve issues at depth, somewhat deeper depth, etc.

CompuDude
09-13-2007, 12:38
LOL K-Valve beat me to the punch by 2 minutes!

(I claim work distractions! LOL)

K-Valve
09-13-2007, 12:41
I have seen a lot of members here saying what size pony they carry. I'm always in favor of redundency, safety and redundency. But how many of you that carry a pony, have actually done the math? Can that tank get you up from depth, not exceeding 30ft/min with a safety stop?

FD

I have. :icon_cool:

K-Valve
09-13-2007, 12:43
LOL K-Valve beat me to the punch by 2 minutes!

(I claim work distractions! LOL)

True, but I like the way you wrote it all out better. :smiley1:

fire diver
09-13-2007, 13:15
K-valve and Compu both gave excellent responses for the math portion. Great job guys!

So now all the info is right here for aspiring pony users.

I use 1.0 as my stress air rate. My normal SAC is usually close to .33
I know divers whos normal SAC is closer to 1.0, thier stress level would probably be closer to 3.0 sac.

One more tip for you SAC newbies.... Want to calc your true working sac? Get to something with a stable depth such as a platform, large rock, etc. Note your depth, and starting PSI and starting time. Now spend several minutes swimming down against the stable object. swim hard, try to push that thing! After several minute have passed (or you just get exhausted) stop. record the time and new tank pressure. Then plug these into your equation to see your working sac. Then use that number for your pony calcs. It's also a good idea to have a buddy close at hand for this.

FD

JCAT
09-13-2007, 13:57
I nominate K-value, compuDude, and Fire divers posts as one sticky to be included in this section.

Pretty much sums up the pony sizes question spot on!

meesier42
09-13-2007, 14:29
wow you can go with anything that you want. technically, if you stay within your recreational dive limits you always have the option to do an emergency free swimming ascent and you don't even NEED a pony bottle

So you think it's a good idea to have "do a CESA" as your backup plan should the proverb hit the spinny thing at 100'?

No, I don't think it is a good idea to do a CESA. Just pointing out the fact that one of the principles of the RDP is that a CESA will get you to the surface without getting bent. The NEED for a pony bottle technically is excempted by proper dive planning and staying within the RDL.

That doesn't mean that I recommend using a CESA as a unless you are really out of options.

RonFrank
09-13-2007, 14:44
I purchased a pony setup at the beginning of the summer. I did so because I read about two different incidents where divers in Coz had complete first stage failures resulting from Alum Oxidation both at depths GT 80fsw. Scary. Another reason is because I generally dive deep wrecks while in FL, and end up with insta buddies.

I wanted my pony for travel. My SAC rate is on the good side, better in warm water, and I determined a 19cf tank would get me to the surface from any recreation depth with a SS and air to spare.

As I want this for travel a 30CF was a bit bigger than I wanted to carry. 19CF was a good compromise between size, and gas. My buddy went with a 14CF tank for the same reasons, but his decision was biased more on size, and not so much gas. His reasoning is that he is rarely at max recreation depth, and from most depths he could surface with a SS with that size tank, but depending on the depth, he would likely breath it close to dry.

I don't always dive with the pony. If I have a good buddy that is an experienced diver, I generally leave the pony behind.

RonFrank
09-13-2007, 14:53
No, I don't think it is a good idea to do a CESA. Just pointing out the fact that one of the principles of the RDP is that a CESA will get you to the surface without getting bent. The NEED for a pony bottle technically is excempted by proper dive planning and staying within the RDL.

That doesn't mean that I recommend using a CESA as a unless you are really out of options.

So at 125fsw, one has a first stage failure, your buddy is narced, and up current. Would you rather

A) do a CESA because there is no need for a pony when it is technically exempted by proper dive planning, or
B) Grab you octo, signal your buddy, and have plenty of air to do a proper ascent with a SS?

I personally think the answer is B, and I GUARANTEE if that is you down there sucking water the answer becomes painfully obvious even if folks love the theorize about how unnecessary they are. My replacement for a pony is a good buddy, but I don't always have one when on vacation.

texdiveguy
09-13-2007, 15:12
A 19cf will fill the average needs of most recreational divers needs.

JCAT
09-13-2007, 15:26
Speaking of travel and a pony. If you follow the TSA regs concerning a pony and airlines, what needs to be done at the distant end? A new vis? ect?

I don't own a pony, but have thought about it for some time.

CompuDude
09-13-2007, 15:40
Speaking of travel and a pony. If you follow the TSA regs concerning a pony and airlines, what needs to be done at the distant end? A new vis? ect?

I don't own a pony, but have thought about it for some time.

If you fly with a tank, yes, you have to take the valve off. This does leave you with an empty bottle.

I'm not sure how you would deal with it at the other end... I've never had to travel with one. Perhaps just screw the valve on and hope no one notices it was completely empty? Worst case, pay your $10 and let them give it a vis. Perhaps that's a small price to pay.

RonFrank
09-13-2007, 15:46
Speaking of travel and a pony. If you follow the TSA regs concerning a pony and airlines, what needs to be done at the distant end? A new vis? ect?

I don't own a pony, but have thought about it for some time.

I've only traveled with a pony once to FL. I had no issue getting it filled. Most shops ignore the empty rule on pony's with traveling divers as they understand the value must be removed. A Friend of mine was diving with us in Coz last January, and he had no issue getting it filled their either.

I would attach the valve upon arriving to your destination, and make sure it's on good. When in FL, I got it filled, and it had a good slow 3000psi fill. What it did NOT have was a tech that made sure the valve was tight! I was only loosing about 250psi a week, but I discovered after a month that it was down to just below 2000psi. I emptied it when I went to get it filled again, and the valve was only hand tightened.

DevilDiver
09-13-2007, 15:47
It's not hte size of your pony, It's how you use it........ Yea, Right!

meesier42
09-13-2007, 16:09
No, I don't think it is a good idea to do a CESA. Just pointing out the fact that one of the principles of the RDP is that a CESA will get you to the surface without getting bent. The NEED for a pony bottle technically is excempted by proper dive planning and staying within the RDL.

That doesn't mean that I recommend using a CESA as a unless you are really out of options.

So at 125fsw, one has a first stage failure, your buddy is narced, and up current. Would you rather

A) do a CESA because there is no need for a pony when it is technically exempted by proper dive planning, or
B) Grab you octo, signal your buddy, and have plenty of air to do a proper ascent with a SS?

I personally think the answer is B, and I GUARANTEE if that is you down there sucking water the answer becomes painfully obvious even if folks love the theorize about how unnecessary they are. My replacement for a pony is a good buddy, but I don't always have one when on vacation.

So, you have entered the world simulataneous mulitple independant failures.
Your scenario-
failure 1, 1st stage failue
failure 2, you were swimming too far from your buddy, beyond the range he is useful and no longer a buddy.
failure 3, your buddy is narced out and you continued the dive without changing your dive plan.

seems to me that Darwin should win this scenario everytime. as the precept of being within recreational limits was violated more than once.

I never said that I wouldn't dive with a Pony, as I will dive one when either solo or with an instabuddy, and a few other circumstances. My point is this, when speaking about a pony bottle, newer divers will tend to start to think they are part of a basic recreational diving rig and that they should carry one. Which is completely false. As we all know over-tasking, often due to unfimilar gear, is a leading cause to diver accidents. A pony bottle is a major addition to the basic gear package and should be trained with frequently and used rarely. As many divers will dive them with the bottle off and when a situation occurs, they either grab the wrong regulator or grab the pony reg which is shut off.

texdiveguy
09-13-2007, 16:50
A pony bottle is a major addition to the basic gear package and should be trained with frequently and used rarely.

** They are easy to use...and should ONLY be used as a contingency gas supply!

As many divers will dive them with the bottle off and when a situation occurs, they either grab the wrong regulator or grab the pony reg which is shut off.

** I dive my pony bottle shut off after I charge the line at the surface...then simply feather it a few times during the dive.



........... :-)

quasimoto
09-18-2007, 12:26
Boy this one went south in a hurry. Personally for less than 100' a thirteen will get you back with a safety stop.

coralcrazed
09-18-2007, 13:06
if you take a look at most calculations that show you how much air you actually need you will realize that you need a 13 or 19 cu ft for most divers to do a safty stop from around 100 feet.

crpntr133
09-18-2007, 23:56
I do have to agree that a 40 would be the best choice IF you are thinking about doing deco diving. 13 or 19 if under 100' for rec.

cummings66
09-19-2007, 11:43
I use a 40 cf myself, but in my future is technical diving and I didn't want to end up with tanks I wouldn't use.

I've done the calc's myself and posted the math and reasons here long ago for others to chew on, and they did too.

Flatliner
09-19-2007, 12:08
Thanks for the info. I am also considering getting a "pony" but I wan't to be able to use it in the future for tech. Is a 40 considered the "normal" deco bottle? If so, why?

charlesml3
09-19-2007, 13:54
For a new diver, no pony at all. It's too much to deal with right away. Stay close to your buddy or DM. When you have a hundred or so dives, reevaluate the situation and see where you stand. I cannot see any reason you'd need a 40 foot slung bottle for warm, clear, Carribbean diving. That is really more for cave and technical diving.

Personally, I use the Zeagle Razor/Envoy combination. The Razor is a tank valve and first stage all in one. Makes things simpler. Most of my diving is in the 60-70' range and I have a very, very good SAC rate so I use a 6 foot tank. It attaches on the right side of my BC just in front of the wing. It's a small tank but I always use Nitrox so if the fit hits the shan I'm going to skip the safety stop. Actually, I'll probably head up to 15' watching the pressure gauge on the Razor. I'll stop there until the guage shows 100 pounds or so.

http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=ZeaglePonyBottleSystem

-Charles

CompuDude
09-19-2007, 14:54
For a new diver, no pony at all. It's too much to deal with right away. Stay close to your buddy or DM. When you have a hundred or so dives, reevaluate the situation and see where you stand. I cannot see any reason you'd need a 40 foot slung bottle for warm, clear, Carribbean diving. That is really more for cave and technical diving.

I agree in general, but there are a lot more kinds of diving than (1) cave and technical diving and (2) warm clear Caribbean diving.

A 40 is definitely overkill for most recreational use for the warm Caribbean scenario, yes. But not necessarily for some cold water wrecks in low vis, however, even without penetration and within recreational depths.

If I was only ever doing one type of diving, I'd make a different decision than if I really mix it up a lot. For warm water diving, I would certainly consider using something as small as a 19cf pony. I don't see the purpose of anything smaller, however, unless you only dive to a max of 60' or so, and then perhaps a 13cf pony would work... but a 19cf tank would still be more versatile.

crpntr133
09-19-2007, 21:49
I don't like the idea of skipping a safety stop even at 60-70'. Why take the chance? I will stick with the no smaller than a 13.

Flatliner, from what I am reading a 40 is the standard deco hang bottle. Why, I guess because most of the time a 40 is all that is needed for most deco. If you get into heavy deco, cave etc. then the ones that I have seen tote AL80's.

skdvr
09-19-2007, 21:58
You can go as small as 19cf, but I think 30 is probably the sweet spot. If you think you may ever go down the technical route, save some money just buy a 40cf tank.

In either case, slinging it to the left if probably one of the better carrying options.

Of course, most of these points were covered in the thread linked above, so this is redundant if you read that already...

I am goign to buy a pony sometime soon and I think that down the road a little ways I would like to get into some deco diving so I am thinking that the 40 would be what I am going to buy. Now when I get something that big is there anything else to consider to offset weight because I plan on slinging the bottle?

Thanks
Phil

CompuDude
09-19-2007, 23:28
You can go as small as 19cf, but I think 30 is probably the sweet spot. If you think you may ever go down the technical route, save some money just buy a 40cf tank.

In either case, slinging it to the left if probably one of the better carrying options.

Of course, most of these points were covered in the thread linked above, so this is redundant if you read that already...

I am goign to buy a pony sometime soon and I think that down the road a little ways I would like to get into some deco diving so I am thinking that the 40 would be what I am going to buy. Now when I get something that big is there anything else to consider to offset weight because I plan on slinging the bottle?

Thanks
Phil
They're surprisingly neutral in the water. You actually barely know it's there... until you go to check your gauges (clipped off on the left also)... then it's a bit of a PITA. But a good Luxfer Al.40 is barely noticeable when you're diving.

skdvr
09-20-2007, 07:18
so do you do anything different with your guages, becuase I do have mine cliped off on the left d-ring?

Phil

CompuDude
09-20-2007, 12:13
so do you do anything different with your guages, becuase I do have mine cliped off on the left d-ring?

Phil

No, it's just harder to get to. Just reach around the back of the cylinder(s) and pull it out from between the cylinder(s) and your body (and then back, of course). You'll learn to work around it, and it gets easier with practice. This is more of an issue with a slung 40 or 80 than smaller cylinders, of course.

crpntr133
09-20-2007, 19:49
I have heard of guys clipping theirs off to a chest d-ring when diving a 40 or bigger. The idea behind it was that they could look down and see the gauge. Personally it looked too cluttered.

GONEHAWKN
09-20-2007, 20:45
put it on the right.....thats where mine goes for the exact reason that i was not happy about the way it interfered with my console.......

ccarter
09-20-2007, 21:02
This has actually remained a pretty civil discussion about ponies compared to other threads I've read.. very surprising! :smiley20:

I run a 19 but I only do the warm tropics diving at less than 100 ft. if you plan on doing stuff deeper or in murkier/more dangerous waters then I might consider something a little bigger.

I got mine for the reasons RonFrank outlined above.. Rental Tanks.. just about every tank I had when I went to Bonaire had pretty f'ed up O-rings.. and I've heard similar stories at other resorty type places. Also photography and insta buddies..

frankc420
10-25-2007, 20:01
I have a 30, I guess I'm going against the grain... 19 would have been my ideal size, but I purchased the 30 w/ tank mount for $40 or so... No brainer :) Too bad I'll probably never use the tank mount =\

charlesml3
10-26-2007, 09:31
I don't like the idea of skipping a safety stop even at 60-70'

I don't think anyone LIKES the idea of skipping a safety stop, but it's just that. A safety stop. In an OOA or severely short on air situation, a safety stop becomes completely skippable.

We can always make the argument that a bigger pony is a better pony but they just become troublesome over 19 cubic feet or so. They're heavy and tend to push you over your weight limit on the airline.

It really is best to look at the type of diving you do, where you dive and then match the pony size to that. If all your diving is local, deep and technical then go for the 40. If you're flying around the world to dive in warm, tropical water and rarely hit 100' then a 13 is fine.

-Charles

Scubastud16
10-28-2007, 23:47
So the general conclusion is that >100 feet, recreational diving, normal-ish SAC, a 19 cu/ft tank would suffice?

Does everyone use a homemade or store-bought (OMS/DR/etc.) stage "sling" kit?

Lastly....I know I can use a "cheapo" (not cheap, but not a brand new Apeks, etc.) reg. Wrap the hose up with hose retainers, and get a small SPG hose?

Thanks!

Danny

chace_nicole
10-29-2007, 00:01
So the general conclusion is that >100 feet, recreational diving, normal-ish SAC, a 19 cu/ft tank would suffice?

Does everyone use a homemade or store-bought (OMS/DR/etc.) stage "sling" kit?

Lastly....I know I can use a "cheapo" (not cheap, but not a brand new Apeks, etc.) reg. Wrap the hose up with hose retainers, and get a small SPG hose?

Thanks!

Danny

Heres a thread on DIY pony sling...it may help:)
http://forum.scubatoys.com/diy/4711-pony-sling.html

cyclone
10-29-2007, 03:12
I carry a HP130 as my pony. My regular tank is AL80. I love it, I sucked air too much on my safety stop. Couldn't help it when I am stressed out for doing the deep dive.:smilie39::smilie39::smilie39:

Seriously, I also have 30. And agree that it is safe enough and the size is decent enough as your support.:smiley20: I usually strapped it on my main tank.:smiley2:

bubble-head
10-29-2007, 06:23
I like the 30, for the minimal extra expense and size. It is barely noticible when slung. I'd rather have more than I, or someone else, needs than not enough.

CompuDude
10-29-2007, 12:33
So the general conclusion is that >100 feet, recreational diving, normal-ish SAC, a 19 cu/ft tank would suffice?

Does everyone use a homemade or store-bought (OMS/DR/etc.) stage "sling" kit?

Lastly....I know I can use a "cheapo" (not cheap, but not a brand new Apeks, etc.) reg. Wrap the hose up with hose retainers, and get a small SPG hose?

Thanks!

Danny
Pretty much, yeah. Specific situations can result in wishing you had more, of course... no such thing as too much air unless you can't carry it! But in general, within the limitations you describe, that all sounds fine.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-02-2007, 12:25
I do not yet use a pony, but I know that for the type of diving I am considering, I need an independent and redundant air source: either doubles or a large tank with a pony.

Think about it.

Can you do a CESA from 33 ft? Likely.
Can you do a CESA from 66 ft? Perhaps. Are you in top shape?
Can you do a CESA from 99 ft? Unlikely.
Can you do a CESA from 132 ft? No %?#$ing way.

Catastrophic gas failures happen, but normal OOA is the main concern. Normal OOA at depth will tend to occur near or perhaps even beyond the NDL. You are asking for trouble if you ascend at 60 ft/min with no stops.

Do you really think your buddy will have enough gas for both of you to ascend safely?

When an OOA happens down there you better believe you will have a heavy SAC rate. According to my calcs, for 99 ft a 13ft pony is barely sufficient, for 132 ft a 19 is barely sufficient.

True story: a student swims up to his instructor at 120ft with eyes as big as saucers and an SPG reading 200psi. The instructor is wearing double 100s, so he gives him his extra secondary. The sudent is so panicked that on the way up, the two of them breath 60 cu ft of gas! Even a 40 cu ft pony wouldn't have been big enough for this guy under these circumstances.

WaScubaDude
11-02-2007, 13:00
A couple more thoughts on Pony descisions:

1) Size needed depends on what kind of diver you are. Do you already suck thru air? Will you freak when your primary air fails and Really suck air from your pony? Could you keep your head and do a CESA from what ever depth your pony gets you to?

2) What kind of dive will you be on? 40ft in warm water with an experienced DB? Quick drop on a wreck in 100ft of water? Solo dive today to take pictures at 60ft? On to Tech diving to 145ft into a cave on a UPV.
Each require different gear based on 1) above, along with your well thought thru risk tolerance.

Other consideration; Are you strong as an OX and don't mind carring more weight, or frail and feel weighted down carring Alum80 already? Do you feel overwhelmed just carring and dealing with other gear like bc, octo, lights, etc.

Make sure YOU are prepaired and comfortable doing any given dive, don't think that the gear will save you. Carry a large bottle of knowledge, and comfort in your head and a pony that fits the situation.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-02-2007, 13:10
A couple more thoughts on Pony descisions:

1) Size needed depends on what kind of diver you are. Do you already suck thru air? Will you freak when your primary air fails and Really suck air from your pony? Could you keep your head and do a CESA from what ever depth your pony gets you to?

2) What kind of dive will you be on? 40ft in warm water with an experienced DB? Quick drop on a wreck in 100ft of water? Solo dive today to take pictures at 60ft? On to Tech diving to 145ft into a cave on a UPV.
Each require different gear based on 1) above, along with your well thought thru risk tolerance.

Other consideration; Are you strong as an OX and don't mind carring more weight, or frail and feel weighted down carring Alum80 already? Do you feel overwhelmed just carring and dealing with other gear like bc, octo, lights, etc.

Make sure YOU are prepaired and comfortable doing any given dive, don't think that the gear will save you. Carry a large bottle of knowledge, and comfort in your head and a pony that fits the situation.

Very well put!

Tableleg
11-02-2007, 14:40
I'd like to bump the suggestion to make this thread a sticky. Especially because of the explanation of the math and everyone's wonderfully different points of view.

WaScubaDude
11-03-2007, 14:01
I'd like to bump the suggestion to make this thread a sticky. Especially because of the explanation of the math and everyone's wonderfully different points of view.

Sounds good. How do you do that?

Puffer Fish
11-03-2007, 14:35
I do not yet use a pony, but I know that for the type of diving I am considering, I need an independent and redundant air source: either doubles or a large tank with a pony.

Think about it.

Can you do a CESA from 33 ft? Likely.
Can you do a CESA from 66 ft? Perhaps. Are you in top shape?
Can you do a CESA from 99 ft? Unlikely.
Can you do a CESA from 132 ft? No %?#$ing way.

Catastrophic gas failures happen, but normal OOA is the main concern. Normal OOA at depth will tend to occur near or perhaps even beyond the NDL. You are asking for trouble if you ascend at 60 ft/min with no stops.

Do you really think your buddy will have enough gas for both of you to ascend safely?

When an OOA happens down there you better believe you will have a heavy SAC rate. According to my calcs, for 99 ft a 13ft pony is barely sufficient, for 132 ft a 19 is barely sufficient.

True story: a student swims up to his instructor at 120ft with eyes as big as saucers and an SPG reading 200psi. The instructor is wearing double 100s, so he gives him his extra secondary. The sudent is so panicked that on the way up, the two of them breath 60 cu ft of gas! Even a 40 cu ft pony wouldn't have been big enough for this guy under these circumstances.
I have to admit a certain humor in your CESA numbers.. it used to be part of OW training to do a safe CESA from more than 60 ft... everyone (I know... what were you thinking).

I've seen someone do one from over 130 ft, without any issue...but I think that is past my limit. 90 ft... I could still do that... although I don't think it is a safe thing to do. A lot of that depends on your ability to hold your breath... I'm still good for 2 minutes, but I know people that are, at best 1 minute, so I'm betting they are at best 45 ft people.

Your pony size numbers (depending on the person) are spot on....and should be taken into consideration when getting one or more bottles.

WaScubaDude
11-06-2007, 15:14
I do not yet use a pony, but I know that for the type of diving I am considering, I need an independent and redundant air source: either doubles or a large tank with a pony.

Think about it.

Can you do a CESA from 33 ft? Likely.
Can you do a CESA from 66 ft? Perhaps. Are you in top shape?
Can you do a CESA from 99 ft? Unlikely.
Can you do a CESA from 132 ft? No %?#$ing way.

Catastrophic gas failures happen, but normal OOA is the main concern. Normal OOA at depth will tend to occur near or perhaps even beyond the NDL. You are asking for trouble if you ascend at 60 ft/min with no stops.

Do you really think your buddy will have enough gas for both of you to ascend safely?

When an OOA happens down there you better believe you will have a heavy SAC rate. According to my calcs, for 99 ft a 13ft pony is barely sufficient, for 132 ft a 19 is barely sufficient.

True story: a student swims up to his instructor at 120ft with eyes as big as saucers and an SPG reading 200psi. The instructor is wearing double 100s, so he gives him his extra secondary. The sudent is so panicked that on the way up, the two of them breath 60 cu ft of gas! Even a 40 cu ft pony wouldn't have been big enough for this guy under these circumstances.
I have to admit a certain humor in your CESA numbers.. it used to be part of OW training to do a safe CESA from more than 60 ft... everyone (I know... what were you thinking).

I've seen someone do one from over 130 ft, without any issue...but I think that is past my limit. 90 ft... I could still do that... although I don't think it is a safe thing to do. A lot of that depends on your ability to hold your breath... I'm still good for 2 minutes, but I know people that are, at best 1 minute, so I'm betting they are at best 45 ft people.

Your pony size numbers (depending on the person) are spot on....and should be taken into consideration when getting one or more bottles.

DANGER, DANGER, DANGER...It has to do with being able to keep your air way open, ie:let a little air out all the way up. Never hold your breath while ascending = very bad.

CompuDude
11-06-2007, 15:29
DANGER, DANGER, DANGER...It has to do with being able to keep your air way open, ie:let a little air out all the way up. Never hold your breath while ascending = very bad.

I'm 99% sure that's not what he meant.

But yes, naturally, your statement is correct: never hold your breath while ascending.

Jipps
11-06-2007, 20:51
The best size is the one that has enough air to get you up safely. Some say it should be enough for just you, others say to have a bigger one for you and buddy. I like diving a 40 because its plenty of air for me and a buddy to make a safe ascent

Puffer Fish
11-06-2007, 21:05
DANGER, DANGER, DANGER...It has to do with being able to keep your air way open, ie:let a little air out all the way up. Never hold your breath while ascending = very bad.

I'm 99% sure that's not what he meant.

But yes, naturally, your statement is correct: never hold your breath while ascending.
No, I'm sure I meant that you should blow your lungs up like a giant ballon... really.

Ok, who, as a diver, does not know not to hold your breath?

Having done several hundred from 60 to 90 ft, I think I would figure that out on... ummm... maybe the first one.

There is a bit of skill to doing it, as gas does not expand the same as you go up...and you have to actually make it to the surface.

Puffer Fish
11-06-2007, 21:06
The best size is the one that has enough air to get you up safely. Some say it should be enough for just you, others say to have a bigger one for you and buddy. I like diving a 40 because its plenty of air for me and a buddy to make a safe ascent
I mostly carry a 6 with me.. although I have a 20. but if I did any major deco diving.. it would be a 40...

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-09-2007, 11:57
Puffer,

Of course the CESA numbers are a SWAG (scientific wild-a**ed guess).

Were these deep CESAs bona fide emergencies or training exercizes?

I believe CESA as a training execrcise is not nearly as difficult as a real one. My assumption is that you are likely stressed at the time and that you do not begin with a full breath.

Can you go without breathing two minutes immediately on completion of a 100 yard sprint? I know I can't.

Puffer Fish
11-10-2007, 10:44
Puffer,

Of course the CESA numbers are a SWAG (scientific wild-a**ed guess).

Were these deep CESAs bona fide emergencies or training exercizes?

I believe CESA as a training execrcise is not nearly as difficult as a real one. My assumption is that you are likely stressed at the time and that you do not begin with a full breath.

Can you go without breathing two minutes immediately on completion of a 100 yard sprint? I know I can't.


Doing a CESA for real means lots of things have gone really, really wrong.. All I have done or seen were training (except two and I just saw them), to get the feeling, and timing and rules down.

You are very, very right about the difference between training and for real.

Being relaxed to know you can comfortably do it helps, but the truth is, if you pass out going up... you pass out.

Can you hold your breath for two minutes after a 100 yard dash?? No. Does being at depth help any - yes. You get to exhale, to get rid of some CO2, but if you run out of cellular O2, it sucks big time.

When I said I could easily do 60 ft, I was assuming it was for real, as I think I could do far greater with practice.. during practice. Just not stupid enough to try it now.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 09:18
Another point about CESA's from depth. Even when they are possible you really want to avoid them.

First, catastrophic gas failure is extremely rare. It does happen I'm told.

However, it routinely happens that inattentive or poorly trained divers nearly or completely exhaust their air supply at depth (>= 100ft). Most air depletions happen not at the beginning of the dive but generally at the end near the NDL. These divers are loaded up on nitrogen placing them at or near the tissue saturation point.

Rapid ascents, given the conditions above, are generally a bad idea from 100 plus feet and several hours from medical attention.

Out of air situations do happen and you should ample gas to handle a normal ascent and safety stop.

It may no be you who needs the ascent gas. It may be your dive buddy with who you may or may not be used to diving with on a regular basis.

Finally, any air is better than no air.


Here are numbers from a table in Alert Diver, Divers Alert Network, April 2001 Pg-13 showing the air required for different ascent and SAC rates. I have not double-checked these numbers but I consider the source pretty reliable.

Air required for ascent (standard cubic feet)

60'/min ascent rate:
Depth Normal Moderate Heavy
66 1.4 2.0 2.8
100 2.6 4.5 5.3
130 4.2 8.0 8.4

30'/min ascent rate:
Depth Normal Moderate Heavy
66 2.8 4.0 5.6
100 5.3 9.0 10.6
130 8.4 16.0 16.8

SAC rates:
Normal = 0.7 cf/min, Moderate = 1.0 cf/min, Heavy = 1.4 cf/min

If you experience a real air 'situation' the odds are that you will not be in the normal or moderate category.

mcc2318
11-27-2007, 13:13
whatever you do, stay away from spare air, its not worth it. save your money and get a pony bottle, I just replaced my spare air with a 13 cuff, the spare air is not a bad idea, but its upkeep cost and lack of air just makes it a pool toy.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 14:01
I disagree. I think your statement is way too strong here.
:smilie40:

A Spare Air might not work for me and my diving but it might be just the ticket for some. IMO, a Spare Air is better for travel and is just fine if your diving is predominantly avove 60 ft.

CompuDude
11-27-2007, 14:19
I disagree. I think your statement is way too strong here.
:smilie40:

A Spare Air might not work for me and my diving but it might be just the ticket for some. IMO, a Spare Air is better for travel and is just fine if your diving is predominantly avove 60 ft.

Actually, I agree it may be good for some, but the problem is few of the people buying them fall into that category. Too many use them as a safety net to protect themselves from, well, themselves, rather than learning good situational awareness. Instead, knowing you have a spare air can breed complacency, and a lack of good skills. And THAT is far more likely to get you killed than a random gear failure. And that complacency is far more likely to get you into a situation that a spare air is not going to get you out of.

Note that the same issue exists with regard to pony bottles, but at least the larger air supply there is going to be more tolerant of mistakes.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-27-2007, 14:28
Of course you are right that there is a risk that a diver taking a pony thinks he has covered the bases and becomes less attentive to other risks.

To me it seems the diver who chooses not to carry a pony or Spare Air is more likely to be the complacent diver. The fact that someone carries one at least shows they realize that sh*t happens.

WD8CDH
12-05-2007, 19:55
If you go with a 30, remember the Luxfur 30 is slimmer than the Catalina 30. The Catalina is fatter but shorter. To me, the Luxfur 30 is less bulky. Before going to a Catalina 30, I would jump up to a 40 which is the same diameter but only a few inches longer.

Of the many ponys that I have, the 19 and the Luxfur 30 are the ones I use the most.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
12-05-2007, 21:15
I picked up a luxfer 40. Probably overkill for the dives I am doing. But it seemed about as easy to sling a 40 as a 30 or 19. And more gas is, well, more gas.

wheelman
12-05-2007, 21:26
I picked up a luxfer 40. Probably overkill for the dives I am doing. But it seemed about as easy to sling a 40 as a 30 or 19. And more gas is, well, more gas.


Sounds like you are on your way to doubles with some isolation... :smiley2:

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
12-05-2007, 21:29
Touche! I now dive a 120 single and cary a 40 pony. My buddy dives double AL80s so I actually have more gas than he does. He has a pair of doubled 130s sitting in his garage though. Maybe he'll pull 'em out just to show me who's boss.