6cuft pony how negative??
- Thread starter domino22
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You use an octo-length hose and tuck it into an elastic band on the bottle.
To deploy, you pull the second stage out and put it behind your neck. The reg goes right in your mouth and feeds "from the right" as is usual; this works fine with an octo-length hose if you are slinging the bottle like a stage.
When diving, you charge the reg before splashing and then TURN IT OFF. This way if it freeflows on entry you've lost almost nothing. Check it before decent; if it freeflowed out the gas, re-charge it and again, turn it OFF. You will get or maybe two breaths if you grab it and haven't (yet) turned it on this way, and the positive pressure keeps water out of the first stage.
To deploy, you pull the second stage out and put it behind your neck. The reg goes right in your mouth and feeds "from the right" as is usual; this works fine with an octo-length hose if you are slinging the bottle like a stage.
When diving, you charge the reg before splashing and then TURN IT OFF. This way if it freeflows on entry you've lost almost nothing. Check it before decent; if it freeflowed out the gas, re-charge it and again, turn it OFF. You will get or maybe two breaths if you grab it and haven't (yet) turned it on this way, and the positive pressure keeps water out of the first stage.
Genesis I agree it is marginal. But this 6cuft is for out of the country travel and the size works good for that. I have a 19cuft also but it is rather large for what I wanted to travel with. With that said I also bought a BP&Wing for travel and will leave the Zeagle Ranger at home although I do like to dive with it. I am trying to get more compact and lighter for trips. As for depth maybe 100ft for a very short time.Most of my time is spent around 40 to 60ft for shooting photos. One other thought to think about is on boat dives that 6cuft of air could get you to another diver were as a total OOA the other divers may be to far away to make it to them and the only choice is up.Ya I know stay with your buddy. I think on my next trip I will do a test run. Dive to 80ft when the computer says it is time to go I will switch to the 6cuft pony for the acent and safety stop and see if I run out or if not I will put the gage on it and see what I have left. If I do run out I will still have my main tank. What do you think? domino22
6cf is not near enough from 80fsw.
Assume you consume 0.7cf/min at sea level.
An ascent at 30fpm puts your "mean" depth at 47 feet (you're going to stop at 15', remember) and requires 2.17 minutes. You will need 3.7cf to reach 15'.
For the 3 minutes at 1.5atm, you will need 3.15cf more. The tank is empty before the 3 minutes are up.
Now, this assumes a few things, none of which will be true when you have a REAL emergency:
1. You will remain PERFECTLY calm and your SAC will not exceed 0.7cf/min @ sea level. Yeah, and I'm the tooth fairy
CONSERVATIVELY, your SAC will double under this kind of stress.
2. You will INSTANTLY begin your ascent upon grabbing the bottle. Ok, really? For every minute you delay, 2.3cf of gas is gone. Do the math.
A diving friend of mine nearly cacked himself this summer diving a small pony. I think his is either a 6 or 9cf; not sure which. Anyway, he was spearfishing near 130', noted that he was about out of time and getting low on gas, and went to unstick the anchor. He huffed and puffed a couple of times, and then drew NOTHING. Tank empty. He immediately drew the pony, yanked the anchor free and began his ascent.
At 60', ascending a bit faster than he should have
he ran out AGAIN. This time he was REALLY out of gas.
Fortunately another diver was on the anchor line at 30' and he was able to make a CESA to him and obtain a working regulator..... A "blow and go" ascent from 130 is a really bad idea.
He was ok, but had another diver not been on the line he might have bent the bejeezus out of himself this way, or possibly worse.
I haven't dove with him for a few months, but I do hope that he has invested in a larger pony bottle......
I have a 19cf and have tested it on an ascent from 130'. I was able to make the ascent, 3 minute safety stop, and still had some gas left. As a consequence I'm fairly confident (from my own testing) that I can indeed depend on the 19cf to get me back to the surface from any non-pentration, non-overhead recreational depth within the NDLs if the water turns brown on me.
I've become rather enamored with doubles of late though, as those have LOTS of extra gas, and really, the penalty for using them isn't that high. However, I'm filling my own tanks - if I was paying for two fills for every dive I might see it differently.
Also, doubles don't travel well
Assume you consume 0.7cf/min at sea level.
An ascent at 30fpm puts your "mean" depth at 47 feet (you're going to stop at 15', remember) and requires 2.17 minutes. You will need 3.7cf to reach 15'.
For the 3 minutes at 1.5atm, you will need 3.15cf more. The tank is empty before the 3 minutes are up.
Now, this assumes a few things, none of which will be true when you have a REAL emergency:
1. You will remain PERFECTLY calm and your SAC will not exceed 0.7cf/min @ sea level. Yeah, and I'm the tooth fairy
CONSERVATIVELY, your SAC will double under this kind of stress.2. You will INSTANTLY begin your ascent upon grabbing the bottle. Ok, really? For every minute you delay, 2.3cf of gas is gone. Do the math.
A diving friend of mine nearly cacked himself this summer diving a small pony. I think his is either a 6 or 9cf; not sure which. Anyway, he was spearfishing near 130', noted that he was about out of time and getting low on gas, and went to unstick the anchor. He huffed and puffed a couple of times, and then drew NOTHING. Tank empty. He immediately drew the pony, yanked the anchor free and began his ascent.
At 60', ascending a bit faster than he should have
he ran out AGAIN. This time he was REALLY out of gas.Fortunately another diver was on the anchor line at 30' and he was able to make a CESA to him and obtain a working regulator..... A "blow and go" ascent from 130 is a really bad idea.
He was ok, but had another diver not been on the line he might have bent the bejeezus out of himself this way, or possibly worse.
I haven't dove with him for a few months, but I do hope that he has invested in a larger pony bottle......
I have a 19cf and have tested it on an ascent from 130'. I was able to make the ascent, 3 minute safety stop, and still had some gas left. As a consequence I'm fairly confident (from my own testing) that I can indeed depend on the 19cf to get me back to the surface from any non-pentration, non-overhead recreational depth within the NDLs if the water turns brown on me.
I've become rather enamored with doubles of late though, as those have LOTS of extra gas, and really, the penalty for using them isn't that high. However, I'm filling my own tanks - if I was paying for two fills for every dive I might see it differently.
Also, doubles don't travel well
Domino22,
Genesis is correct, and I am guilty of assuming - e.g. that you wanted a drysuit inflation system.
A 6 cu ft tank is entirely inadequate for the purpose you describe.
Lets run some numbers:
Lets assume that you have some type of OOA situation in a recreational no-decompression-limit dive environment.
Furthermore, lets assume, for the sake of discussion, that you want a redundant air source because you might be at depths to, say, 100'. On a charter boat, with potentially an unknown buddy.
Because running out of air (which of course won't ever happen to you because you track your dives) tends to get divers excited, lets assume finally that your rate of air consumption (Respiratory Minute Volume - RMV) = 1.2 cubic feet per minute. Thats about double normal RMV for many divers, but in a really bad situation it may be just about right. Our respiration goes up significantly when we're anxious.
Assume you want:
3 minutes available to respond to the sudden situation (communicate with buddy, extract yourself from some situation you're in, untangle yourself, whatever);
3 minutes to ascend to 10' at a rate of 30 fpm (because if you've got a problem at 100' there is no need to compound it by ascending too fast from too deep for too long);
a 3 minute safety stop at 10'; and
a 1 minute ascent to surface from safety stop;
Thats 10 minutes of air you want to have available in an emergency situation when you're going through air at a rate of 1.2 cu ft per minute.
Thats also bare minimum, given the above assumptions.
10 minutes x 1.2 cu ft per min. = 12 cubic feet minimum
You can see that a 6 cu ft tank isn't adequate. While a 13 cu ft tank may be barely adequate, if you're going to carry a bailout bottle anyway, I might go with the 19 cu ft. Underwater emergencies don't tend to happen the way you planned for.
And Genesis is right that a bailout bottle should be slung, so that you can get at the valve and/or remove it to hand it to another diver if need be. Here are some instructions, etc.:
http://www.diverite.com/resource/stage/index.htm
You may not agree with my assumptions or my numbers. Other guys will offer their views as well. But I don't think you'll see anyone recommending you consider a 6 cf bottle for bailout purposes.
FWIW. Your mileage may vary.
Doc
Genesis is correct, and I am guilty of assuming - e.g. that you wanted a drysuit inflation system.
A 6 cu ft tank is entirely inadequate for the purpose you describe.
Lets run some numbers:
Lets assume that you have some type of OOA situation in a recreational no-decompression-limit dive environment.
Furthermore, lets assume, for the sake of discussion, that you want a redundant air source because you might be at depths to, say, 100'. On a charter boat, with potentially an unknown buddy.
Because running out of air (which of course won't ever happen to you because you track your dives) tends to get divers excited, lets assume finally that your rate of air consumption (Respiratory Minute Volume - RMV) = 1.2 cubic feet per minute. Thats about double normal RMV for many divers, but in a really bad situation it may be just about right. Our respiration goes up significantly when we're anxious.
Assume you want:
3 minutes available to respond to the sudden situation (communicate with buddy, extract yourself from some situation you're in, untangle yourself, whatever);
3 minutes to ascend to 10' at a rate of 30 fpm (because if you've got a problem at 100' there is no need to compound it by ascending too fast from too deep for too long);
a 3 minute safety stop at 10'; and
a 1 minute ascent to surface from safety stop;
Thats 10 minutes of air you want to have available in an emergency situation when you're going through air at a rate of 1.2 cu ft per minute.
Thats also bare minimum, given the above assumptions.
10 minutes x 1.2 cu ft per min. = 12 cubic feet minimum
You can see that a 6 cu ft tank isn't adequate. While a 13 cu ft tank may be barely adequate, if you're going to carry a bailout bottle anyway, I might go with the 19 cu ft. Underwater emergencies don't tend to happen the way you planned for.
And Genesis is right that a bailout bottle should be slung, so that you can get at the valve and/or remove it to hand it to another diver if need be. Here are some instructions, etc.:
http://www.diverite.com/resource/stage/index.htm
You may not agree with my assumptions or my numbers. Other guys will offer their views as well. But I don't think you'll see anyone recommending you consider a 6 cf bottle for bailout purposes.
FWIW. Your mileage may vary.
Doc
OK I follow your math and it makes sense. It will just be a shame to have to travel with the 19. But it and the bp&wing will still pack easier than the Ranger. But that little 6cuft mounted to the BP was sure compact and out of the way.I guess it will not be getting the frequent flyer miles. I will ck out the web site for mounting/carrying the 19 tomarrow I have a meeting tonight. Thanks for the answers and the numbers to make it understandable.Would have been a interesting test dive. domino22
Actually, taking pressure into account, with RMV of 1.2, just the ascent from 100ft and safety stop will take close to 15cf. So with a 19cf tank, you get only 1min at depth before you have to start ascending to have air for a safety stop. With a 13cf, you just barely have enough for a safe ascent, if you start the ascent immediately, and omit the safety stop.
I see a 19cf as the only rational compromise.
If you need bigger (and you might), you're better off with doubles.
Smaller, you might not get back to the surface.
So, I use a 19cf for single tank dives where I have a reason to think I might need an "aluminum buddy."
If you need bigger (and you might), you're better off with doubles.
Smaller, you might not get back to the surface.
So, I use a 19cf for single tank dives where I have a reason to think I might need an "aluminum buddy."
I love this board I ask a ? and get the answers I need and from more than one source. And on this post every one seems to agree more or less the 6cuft is not a good idea. Now I need to really figure out why I bought it before I posted "SIZE" and why I am sitting here looking at 6 sitting next to the 19 "SIZE". Anyone need a brand new 6cuft bottle never used only touched? OUCH!
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