View Full Version : Free Flow and Pony Advice
AllynCarter
03-02-2010, 15:56
Hi All,
I had a somewhat unenjoyable experience at Dosthill on Sunday when my regs free flowed at 18m. I switched to my Octo, but that, too free flowed after about 3 breaths. My buddy was a within sight, but a little deeper. I was unable to attract his attention (he was writing on a slate at the time and concentrating deeply), so I began my ascent, breathing from the free flowing octo. I was near a buoy line, so I used it to regulate my ascent and made it to the surface in about 90s, with no more damage than an iced up tongue and teeth - uncomfortable but nothing lasting.
This incident has, however, brought home to me the value of a truly independent air supply. I gather it's the 1st stage that has a problem in a free flow, so it's hardly surprising that both my regs suffered.
The upshot of this is that I am now looking at 3l Pony set ups - I can't afford, and nor do I think I am ready for, a twin set. Obviously, I need a pretty good reg -not some old cast-off - on the Pony, as, if I need it, I really will want it to work. I am slightly surprised that my initial glances at internet retailers suggest thats that A-Clamp regs are still very common for Ponys. Is there a reason for this? I though that DIN was taking over in most places.
Further to that, any recommendations would be welcome. I will be visiting my LDS for advice and to make the purchase, but I'd like to be au fait with some of the issues beforehand.
Thanks in advance,
Allyn
Richard Whitcombe
03-02-2010, 16:24
Seems you handled the situation well enough - cold water freeflows arent fun but are very common. As you say its usually first stage flowing (icing often) causing it so its going to affect both regs AND empty your tank quickly.
You also discovered that the nice warm fluffy theory of buddy diving vs the real world are completely different things.
Id always recommend to everyone that you go into water with the equipment needed to get yourself out of trouble WITHOUT having to blindly rely on a 3rd party. Hence the redundant gas source.
There is no problem with a pony provided you know what it can do but more importantly what it cant do and dive within those limitations.
I know for example that for my gas consumption rate a full 3l pony should get me out of jail from the mid 30m range with a 3 min safety stop and normal speed ascent. Deeper than that or any deco it wont. So do the sums for yourself to set a max depth you should be prepared to dive with it.
Get a good reg. That doesn't have to be the latest model by any means but get a good reg. Usual suspects such as Apeks, scubapro etc are recommended. As for "why a-clamp" mainly because the UK is still fairly in the dark ages when it comes to connections, like the USA it really does refuse to modernise (especially in clubs where dinosaurs lurk...) so there is still a market for them so they are still sold. Buy DIN though..You know it makes sense! Also get an SPG for it - nothing guaranteed to stress you out more than breathing a tank and not knowing how much gas it has in it and wondering if each breath could be the last one it gives.
Give some thought to how you want to mount the pony as well (back on the tank vs side mount like a stage etc). Id recommend side.
If you're doing no-stop diving and shallower than 30m you dont really need the extra expense or complications a twinset brings. A pony will do the job nicely.
I am slightly surprised that my initial glances at internet retailers suggest thats that A-Clamp regs are still very common for Ponys. Is there a reason for this?
Shops will stock what they can sell at a profit. That doesn't mean that it's any good...
I though that DIN was taking over in most places.
*Has* taken over. A-clamp regs are a legacy we'd be better off without.
Further to that, any recommendations would be welcome.
Buy DIN.
I'd like to be au fait with some of the issues beforehand.
Take a look at the UKRS page (http://www.ukrecscuba.org.uk/ukdiver/dinyoke.htm) on DIN fittings. That's ten years old now, but it's still right.
Vic.
Richard Whitcombe
03-02-2010, 16:39
Every time someone turns up here with A-clamp regs (and 99% of them are british) we groan as it usually takes 30 minutes to find a combination of tank valve and DIN insert adaptor that actually seals on their regs, especially scuba pros.
And by day 2 they've lost it or forgotten to bring the insert....
Hi All,
I had a somewhat unenjoyable experience at Dosthill on Sunday when my regs free flowed at 18m. I switched to my Octo, but that, too free flowed after about 3 breaths. My buddy was a within sight, but a little deeper. I was unable to attract his attention (he was writing on a slate at the time and concentrating deeply), so I began my ascent, breathing from the free flowing octo. I was near a buoy line, so I used it to regulate my ascent and made it to the surface in about 90s, with no more damage than an iced up tongue and teeth - uncomfortable but nothing lasting.
This incident has, however, brought home to me the value of a truly independent air supply. I gather it's the 1st stage that has a problem in a free flow, so it's hardly surprising that both my regs suffered.
The upshot of this is that I am now looking at 3l Pony set ups - I can't afford, and nor do I think I am ready for, a twin set. Obviously, I need a pretty good reg -not some old cast-off - on the Pony, as, if I need it, I really will want it to work. I am slightly surprised that my initial glances at internet retailers suggest thats that A-Clamp regs are still very common for Ponys. Is there a reason for this? I though that DIN was taking over in most places.
Further to that, any recommendations would be welcome. I will be visiting my LDS for advice and to make the purchase, but I'd like to be au fait with some of the issues beforehand.
Thanks in advance,
Allyn
Allyn
Have a look at this thread, discussion about freeflows & prevention
http://www.bsacforum.co.uk/forums/showthread.php?p=124192#post124192
A truely independent alternate gas source is always a better solution that relying on 1 cylinder as the gas source.
Gareth
XTX40/DS4 for £110
Button gauge £20
Ally pony cylinder £100
2 90mm boltsnaps £10
Jubilee clip £3
Bit o string £free
Bit o hosepipe £free
Bit o electrical tape over the jubilee £free
2 snoopy loops £free
Top bit of kit, cold water reg, ally cyl so it doesn't upset your balance and... you're away with a neat little side-slung unit that is nice and flexible. If you can get over to Nottingham I'll even rig it and if it's a pool night, show you how to sling and use it.
Woz,
have you got any piccies of this?
I think that Woz may mean ATX40/DS4, not XTX40/DS4 for £110. From what I've heard should still be just as good a reg - sealed first stage for cold water etc.
http://www.sdswatersports.co.uk/apeks-atx40ds4-552-p.asp
I think that Woz may mean ATX40/DS4, not XTX40/DS4 for £110. From what I've heard should still be just as good a reg - sealed first stage for cold water etc.
http://www.sdswatersports.co.uk/apeks-atx40ds4-552-p.aspThey're identical. I think Divelife are doing the xtx for £110
Woz,
have you got any piccies of this?http://www.divelife.co.uk/images/large/HalcyonBrushedAliStageCylinder.jpg
As nice it would be, afraid not - £175 http://www.divelife.co.uk/product_info.php?products_id=1551
I’d run with pretty much all of the above advice, bar the Button Gauge. As you pointed out, you will be bailing out onto the Pony when it’s all gone pearshaped. Trying to read a gauge that’s the size of your Thumb Nail (if you’re diving it side slung) is challenging when you are under pressure. And impossible to read if you have it back mounted. Choose a nice clear gauge that you can understand on the surface, so that when you are stressed out of your box, you can still read and understand it. Knowing how much gas you really have left in your tank can be a huge comfort sometimes.
The other thing to consider is putting a different mouthpiece on your Pony Reg. It has been known for people to jump in with their Pony Reg in their mouth and then wondering why they run out of gas when their gauge (on their main cylinder) is still reading 232 bar. The better course of action would be to fit a Comfi Bite, or a SeaCure mouthpiece to your main regulator, and have a bog standard mouthpiece on the Pony. That way if you do put it in your mouth you have a physical reminder “is this the right reg” and in times of great stress, the diver using the Pony (which might not be you), won’t have to suffer from the added complication of a bespoke mouthpiece.
I’d run with pretty much all of the above advice, bar the Button Gauge. As you pointed out, you will be bailing out onto the Pony when it’s all gone pearshaped. Trying to read a gauge that’s the size of your Thumb Nail (if you’re diving it side slung) is challenging when you are under pressure. And impossible to read if you have it back mounted. Choose a nice clear gauge that you can understand on the surface, so that when you are stressed out of your box, you can still read and understand it. Knowing how much gas you really have left in your tank can be a huge comfort sometimes.
The other thing to consider is putting a different mouthpiece on your Pony Reg. It has been known for people to jump in with their Pony Reg in their mouth and then wondering why they run out of gas when their gauge (on their main cylinder) is still reading 232 bar. The better course of action would be to fit a Comfi Bite, or a SeaCure mouthpiece to your main regulator, and have a bog standard mouthpiece on the Pony. That way if you do put it in your mouth you have a physical reminder “is this the right reg” and in times of great stress, the diver using the Pony (which might not be you), won’t have to suffer from the added complication of a bespoke mouthpiece.Button gauges are only any good to see if it's full or not. I wouldn't use one underwater!
If you don't want to change a mouthpiece, stick a small rubber loop over the hole in the mouthpiece and over the fromt of the reg (over the purge button). Then you can stick it in your mouth and breathe but you immediately know it's not the correct one.
As nice it would be, afraid not - £175 http://www.divelife.co.uk/product_info.php?products_id=1551You need to pick up the phone and talk to Brett. Or was it GoDive going them at the NEC for that price? I forget.
SDS ATX40/DS4 £109 +pp
http://www.sdswatersports.co.uk/apeks-atx40ds4-552-p.asp
Nigel N
Paul Burgess
04-02-2010, 16:03
All the points raised regarding equipment are all valid enough. A redundant gas source is a good thing however you go about it.
The one thing you acknowledge but may not be addressing is that your buddy failed you when you needed him and you are fortunate that the consequences were not more serious. It may be hard to raise, but you shouldn't dodge the discussion that he failed you on this dive through inattentiveness. He should really be taking a hard look at his level of situational awareness and team positioning.
If there is one equipment recommendation that helps with this, it is for a HID torch with a tightly focused beam. This helps no end with underwater cohesiveness and communication.
The way I dive, I build in multiple layers of redundancy. Redundant equipment for one, but also another one or two redundant brains. I make sure I buy quality equipment. I also dive with buddies I trust.
When I'm teaching, a good guide is: "if you can reach out and hold hands with your buddy, your positioning is spot-on"
ChristianG
04-02-2010, 16:27
When I'm teaching, a good guide is: "if you can reach out and hold hands with your buddy, your positioning is spot-on"
True.
Then again I don't teach and my own attitude, except when I'm actually in buddy mode, when I tend to stick like glue never expecting that the buddy is going to get me out of the hole, is that I have to look after #1, that's me to dispel any doubt out there, all on my ownsome.
Self-sufficiency (by way of a pony tank) is a good thing.
Nigel Hewitt
04-02-2010, 16:43
While it's nice and cosy to trot out all the mantras about good buddy skills I don't want to spend the whole dive eagerly watching some bod, who may be far more competent than I am, in case he needs something. I am going to take my eyes off him and look at all this stuff I've come to see for a good part of the time.
If your problem management plan involves me hanging round your neck we are in a pupil/instructor relationship and, although it has its place and I'm happy to be on either end, I don't want to do it all the time on every dive.
Worse still: If I have a camera in my hands and you want an instant response be within range to hit me. Don't be thirty feet away and expect me to be on watch.
my buddy is normaly at least 4 meters away, even in bad vis, just reel them in witht eh buddy line. tho the 6 meter one is a little excessive
johnskerry
04-02-2010, 20:30
Personally I would go for 3L steel on a Northern diver quick release clamp, with a Poseidon Reg, I would also use the Pony to inflate the jacket if you are using your dry suit for buoyancy. I would also invest in a whip so I could keep it toped up from the main cylinder after each fill (saves on paying out for a few bar in a 3 fill). I would dispense with the octopus from the main cylinder as well, no need to clutter yourself up with three regs. Simple!
John
Nigel Hewitt
04-02-2010, 20:52
I would dispense with the octopus from the main cylinder as well, no need to clutter yourself up with three regs. Simple!
I really can't agree with that one.
The octo and the pony are for different purposes.
The octo is for you.
The pony is for me.
johnskerry
04-02-2010, 21:11
I really can't agree with that one.
The octo and the pony are for different purposes.
The octo is for you.
The pony is for me.
I know what you are saying however consider this. The original problem was a free flow to some extent caused by cold water diving, as you know two divers breathing off of one cylinder valve are more likely to cause a free flow, hence why you see so many Y valve cylinders in colder climates.
If you have the Octopus on the Pony it’s there for you and me and it has no detrimental effect on the other reg.
If either you or your buddy need an alternate air source, in both cases the dive is aborted and the accent must be commenced.
It’s a matter of how you look at it, but what would you do if your buddy needed your Octopus , and this caused a free flow, would you give your buddy the pony reg or take it for yourself?
johnskerry
04-02-2010, 21:18
I really can't agree with that one.
The octo and the pony are for different purposes.
The octo is for you.
The pony is for me.
I know what you are saying however consider this. The original problem was a free flow to some extent caused by cold water diving, as you know two divers breathing off of one cylinder valve are more likely to cause a free flow, hence why you see so many Y valve cylinders in colder climates.
If you have the Octopus on the Pony it’s there for you and me and it has no detrimental effect on the other reg.
If either you or your buddy need an alternate air source, in both cases the dive is aborted and the accent must be commenced.
It’s a matter of how you look at it, but what would you do if your buddy needed your Octopus , and this caused a free flow, would you give your buddy the pony reg or take it for yourself?
And when you don't take the pony?
I'd say an AS is mandatory and the pony is an extra.
Personally I would go for 3L steel on a Northern diver quick release clamp
The problem with clamps like that is that one part is fairly firmly fixed to the main cylinder; this makes swapping out the cylinder quite time-intensive.
There are clamps that fit under the cam band - this makes changing the cylinder much easier, but there are variable qualities around. Some will hold the pony very well, some will not.
I would also use the Pony to inflate the jacket if you are using your dry suit for buoyancy.
No, I wouldn't agree with that either. Using thepony means it will tend to get depleted. It's all very well saying that it will be topped up - but that's exactly the sort of thing that gets forgotten.
BCs all have oral inflation. It's a good skill to practice...
I would dispense with the octopus from the main cylinder as well, no need to clutter yourself up with three regs.
No, absolutely not. This approach means that an OOG diver only gets a small reserve. Get OOA divers on the big source to start with, and move to the pony if necessary.
Vic.
Personally I would go for 3L steel on a Northern diver quick release clamp, with a Poseidon Reg, I would also use the Pony to inflate the jacket if you are using your dry suit for buoyancy. I would also invest in a whip so I could keep it toped up from the main cylinder after each fill (saves on paying out for a few bar in a 3 fill). I would dispense with the octopus from the main cylinder as well, no need to clutter yourself up with three regs. Simple!
John
your thinking its a kind of lopsided twinset which it isnt.
i feel alot of people are not that good at understanding what a pony is. its an oh**** get me out of trouble backup. to run anything other than a single reg and guage off of it is pointless.
micromouse
04-02-2010, 23:56
The problem with clamps like that is that one part is fairly firmly fixed to the main cylinder; this makes swapping out the cylinder quite time-intensive.
The Northern Diver version is threaded onto the cam band, with the rest of it clipped onto the pony with jubilee clips. No problems in swapping main tanks, and quite happy to dive without the pony attached.
MM
northern_diver
05-02-2010, 01:13
A ND clamp isnt really much of a hinderance in replacing a bottle, especially if you have dual bands (i do) or a cylinder hight hanger thingy (again i do).
They are simple to take off/thread on, especially if you learn to thread the cam band or look at the picture that lots of BCD's have sown into the bands.
Personally however, as often than not, i sling the pony..i can hand it off/monitor it/make sure in breathing the right source/etc etc and i think its a better option in many situations. PERSONALLY
My 3l has a contents guage(on hose) and a balanced, cold water reg on, the mouth peice is different, as is the reg to my main regs (DV and octo) It's A-clamp...but only as i havent replaced it yet due to money/time.
Works well and it has both a clamp attachment and p-clips, so is versitile in its application.
Fluid kit, to allow good suitabiliy for the dive.
John
davebarber
05-02-2010, 08:13
They're identical. I think Divelife are doing the xtx for £110
Woz
I recently bought the ATX40, it could do with a bit of detuning especially for use as pony. Do I wind in the allen key way to increase the cracking resistance? How much would you recommend? half a turn? More? Less?
I have also have dispensed with the Octopus when I am using the pony.
Cheers
Nick Argue
05-02-2010, 09:48
<snip>
I have also have dispensed with the Octopus when I am using the pony.
<snip>
I really don't like this setup. If your buddy goes OOG and you put them on the big bottle then you're on the pony. You've just removed your access to your nice big bottle of gas. If you rig it so the OOG diver get the pony they're now on the small bottle with no access to the big one. Either way all that air in the big bottle can't be shared.
IMHO just two regs only works with two equal sized bottles. As other have said a pony's not for sharing.
davebarber
05-02-2010, 10:01
I've donated twice in practice. both times I donated my primary and switched to the pony. The OOG was stressed and needed the big bottle, I wasn't. I am very comfortable abhorting the dive and relying on the pony for the ascent.
Nigel Hewitt
05-02-2010, 10:06
I am very comfortable aborting the dive and relying on the pony for the ascent.
Fair call.
If you're happy that it matches your diving it works for you.
We'd better not make too much noise or the NDC will do some tests 500 meters into a cave, decide it's dangerous and ban it.
Woz
I recently bought the ATX40, it could do with a bit of detuning especially for use as pony. Do I wind in the allen key way to increase the cracking resistance? How much would you recommend? half a turn? More? Less?
I have also have dispensed with the Octopus when I am using the pony.
CheersNot telling you unless you put your octo back on :)
(Set lever to -, hit the purge button and release. It should stop. Set to +ve and repeat. It should freeflow on a properly set up Apeks 2nd. Turn allen key thingy clockwise 1/2 turn and repeat until it's tricky to get it to freeflow on + without really giving the purge a proper hard clonk. Caveat- don't try this unless you're totally confident you know what you're doing. If you're not- take to your local shop who can pretend they know what they're doing and ar$e it up properly.)
I really don't like this setup.I really don't like the idea of having a stressed diver on the same 1st stage as me when I really need that 1st stage to keep working. The HSE take a similar view.
If your buddy goes OOG and you put them on the big bottle then you're on the pony. You've just removed your access to your nice big bottle of gas.If you have planned your bailout properly, you should not need access to the big bottle.
If you rig it so the OOG diver get the pony they're now on the small bottle with no access to the big one.It is not ideal as the OOA's breathing rate may be elevated so it would be better to have them on the bigger cylinder. The stressful bit is establishing the air share, once the diver is breathing safely, you could always suggest they switch to the regulator you would prefer them to use.
IMHO just two regs only works with two equal sized bottles. As other have said a pony's not for sharing.All comes down to the gas planning IMVHO. As a KISS fan, one AAS is enough for every other config I dive, so it's enough for a pony.
What I will add is, if you are going to drive a jacket from your pony do not neglect to check the pony contents before each dive and preferably refill.
Nick Argue
05-02-2010, 10:31
I've donated twice in practice. both times I donated my primary and switched to the pony. The OOG was stressed and needed the big bottle, I wasn't. I am very comfortable abhorting the dive and relying on the pony for the ascent.
Fair enough; I assume your setup is primary donate with a longer primary hose then? The only other diver I've seen who dives like this has a standard length primary with a slightly longer hose on the pony.
Fair enough; I assume your setup is primary donate with a longer primary hose then? The only other diver I've seen who dives like this has a standard length primary with a slightly longer hose on the pony.Would you like a tin opener for that particular can of worms?
We'd better not make too much noise or the NDC will do some tests 500 meters into a cave, decide it's dangerous and ban it.Is it Friday ;)
You remember they changed the reserve from 50bar to 1/3. Well if you ask an OD to plan a dive to 20m, using the 25lpm rate we teach them, and a 12ltr cylinder...You don't have time to teach them anything.
As an exercise I calculated how much gas you need to get a diver safely back to the surface when they are breathing at the maximum rate an average human is likely to maintain through a regulator (100 lpm - 150 lpm). Forget twinsets and rebreathers, the only safe option is surface supply :)
24lpm is much easier to teach... answers on a postcard as to why?
Nick Argue
05-02-2010, 10:40
I really don't like the idea of having a stressed diver on the same 1st stage as me when I really need that 1st stage to keep working. The HSE take a similar view.
If you have planned your bailout properly, you should not need access to the big bottle.
It is not ideal as the OOA's breathing rate may be elevated so it would be better to have them on the bigger cylinder. The stressful bit is establishing the air share, once the diver is breathing safely, you could always suggest they switch to the regulator you would prefer them to use.
All comes down to the gas planning IMVHO. As a KISS fan, one AAS is enough for every other config I dive, so it's enough for a pony.
What I will add is, if you are going to drive a jacket from your pony do not neglect to check the pony contents before each dive and preferably refill.
Point taken about two divers on one first stage; though a modern first stage that shouldn't be an issue after all it's the standard OOG setup for 95% of the worlds divers.
Agreed; it all comes down to gas planning.
Nick Argue
05-02-2010, 10:52
Would you like a tin opener for that particular can of worms?
but at least I refrained from asking whether it was Stuffed or Looped
but at least I refrained from asking whether it was Stuffed or Looped[JACK BAUER MODE]
Put the can down.
Step away from the can, lie on the ground with your hands behind your head.
Now!
Nigel Hewitt
05-02-2010, 11:41
24lpm is much easier to teach... answers on a postcard as to why?
12L tanks?
Some people can't do mental arithmetic.
You remember they changed the reserve from 50bar to 1/3.
Don't get me started on that one.
davebarber
05-02-2010, 11:57
Fair enough; I assume your setup is primary donate with a longer primary hose then? The only other diver I've seen who dives like this has a standard length primary with a slightly longer hose on the pony.
Nope all standard hoses. I'm old school I'm afraid, we were taught to share air on a single DV. Just doing what comes naturally to me. In practice once you go to a divers aid you are trusting to luck they don't drown you. You grab them, keeping close contact. Short hose is fine. You want to keep eye contact.
I'm not promoting this, just telling what happened to me.
graham nurse
05-02-2010, 13:19
Point taken about two divers on one first stage; though a modern first stage that shouldn't be an issue after all it's the standard OOG setup for 95% of the worlds divers.
Agreed; it all comes down to gas planning.
95% of the worlds divers do not dive in water less than 6 degrees, most free flows happen during the winter while diving in quarries. This is one of the reasons an AS running from a second second stage is recccomened.
Graham.
I have also have dispensed with the Octopus when I am using the pony.
This is a joke, right?
This is a joke, right?Take it up with the HSE Terry. See whether they laugh about it.
johnskerry
05-02-2010, 22:19
And when you don't take the pony?
I'd say an AS is mandatory and the pony is an extra.
Clearly if you were to configure your kit as I suggested, you must take the pony and it must be full. When I dived on a single plus pony that’s how I configured my kit. How you configure your kit is down to personal preference, as long as it works and achieves its purpose does it matter. You suggest side slinging a 3, and that may work for you, personally I find a 3 to small to side sling, and I have front slung the cylinder which I personally found much easier. Only trial and error will find what works best for the kit you have at the time.
John
This is a joke, right?
Is it prohibited by BSAC?
Janos
When I was OC I had a 12L and a 3L. The 3L was held on with twin cam bands. I was was taught to always have redundancy in all things life dependant. The twin cam bands held the 3L solid and it was easy to change the 12s. I had a scubapro airII for emergencys. If my buddy needed gas I knew he would take the one from my mouth or I would donate the one I was using as I and he knew it was working and had the right gas. The AirII was always in the same place and was easy to find. The second stages had flow stops on them, I found a 12L would empty very fast at 30m and bending the hose between the first and second stage did not work at this depth. A flow stop is easy to use and works....£20 well spent.
http://www.apdiving.com/rebreathers/components/flowstop/
I also use this on the YBOD.
davebarber
06-02-2010, 08:50
This is a joke, right?
Don't laugh at my kit its not polite.
This isn't my can of worms I was just agreeing with an earlier poster. johnskerry.
I strongly suspect that the primary function of a lot of kit these days is to remove money from divers wallets.
ChristianG
06-02-2010, 13:58
You suggest side slinging a 3, and that may work for you, personally I find a 3 to small to side sling, and I have front slung the cylinder which I personally found much easier
I agree with you that front slung would be my choice nowadays except that it's well nigh useless for me because I mostly happen to often carry a rather large camera system which means that front slung gets seriously in the way of my photography. So does a conventional second reg which is necklaced, as JB is often wont to point out, quite correctly I might add.
Now if I'm diving with someone I almost never take the camera which changes things somewhat. It follows that if I'm taking the camera I tend to dive self sufficient which, again like JB, means an AIR2. I don't front sling the pony if I'm diving buddied if only because it's set up at my left side and I couldn't be bothered to change the config for these fairly rare occasions. Depending on depth I either dive twins or a single and a 3l pony, but never a single by itself. Not for a long time now anyway.
terencecooper65
03-04-2010, 15:05
As other people have mentioned, welcome to the real world of diving. When people say to me that you dont need a pony, I just tend to cringe inside. While BSAC teach buddy diving, I feel we all need to be self sifficient to a point. A pony doesnt weigh that much, may cost a few quid but its always there, unlike your buddy at times. And as you discovered, its the first stage that starts the problem. So if yours has played up due to the cold, your buddies is near too, so having two divers breathing off it, might just be enough to push it over the edge too.
As an experiment, me and a friend, tried coming up from the bottom of stoney (35m) on a pony. we did two deep stops, of two mins a piece and a three min safety stop. Total asscent time 10 mins and we both surfaced with 70bar remaining. Now i know if you have had a problem, you will be breathing heavier but you wouldnt do deep stops either, so there should be sufficient for a safe asscent down to 35m.
Im now on twins but my daughter has my pony setup and i wouldnt have her dive without one.
iainmsmith
05-04-2010, 17:01
As an experiment, me and a friend, tried coming up from the bottom of stoney (35m) on a pony. we did two deep stops, of two mins a piece and a three min safety stop. Total asscent time 10 mins and we both surfaced with 70bar remaining. Now i know if you have had a problem, you will be breathing heavier but you wouldnt do deep stops either, so there should be sufficient for a safe asscent down to 35m.
Im now on twins but my daughter has my pony setup and i wouldnt have her dive without one.
A contrary experience, for balance:
On one occasion I lifted someone out of 30m after an inflator failure. Downloading their AI computer afterwards, showed that their peak SAC was 96 lpm. That's just over 7 min at the surface on a 3L pony or less than 1min 40s at 35m. How long to get the ascent going? Other agencies teach 1 min to sort your life out at depth for gas planning purposes. That leaves about 40s of gas left...
That dive was the one that taught me what people meant when they said "If you think you need a pony, you need twins."
Iain
I have to agree with Iain.
Early last year I was diving with a friend in Wastwater when he had a brown stuff in spinney thing moment – a free flow at 28m which then got a little worse; let me explain.
I normally dive with a twin set (12’s @ 232bar) and donated a reg – lets not go down the rights and wrongs of primary donation (as that discussion has got seriously out of hand), buts that’s what I did and we survived.
Now, I normally have a good gas consumption rate, usually around 15L/min (even in the dark and cold) and when the moment happened I had 190bar across the two cylinders. When we arrived at the surface just over 2 frantic minutes later (as he became inverted as well – don’t ask, but when it goes wrong, it really goes wrong…) the contents of my cylinders had dropped to 110bar. So if we do the maths, the average SAC on that is around 200L/min EACH.
Would a pony have got us out of that little predicament – maybe if it was just me breathing from it – if we had any mandatory compression - I don’t think so….
Don’t take this out of context, I’m not saying everybody should ditch their ponies, rush out and buy a twin set – but you have to seriously consider the equipment you’re using for the type of diving your undertaking.
And the reality check - when it goes really wrong the 25L/min breathing rate doesn’t even come close.
Andy
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