View Full Version : Survey: use of long-hoses?
Turtle Dude
08-07-2008, 14:37
Am interested to know how many people are diving with primary or secondary long-hoses (typically 5-7ft), as advocated by a number of diving groups for out-of-air situations.
Neither.
Id give them the pony reg, clip the cylinder off to their jacket and we'd ascend.
I dive a normal size reg hose on each side when doing the indy 12s, and carry 3L of bailout gas, matched as near to the MOD of the dive, but sometimes a little more upto 1.5.
Have practiced it with my buddy a few times, but we've never used it so far. I'd say its more likely to happen from an external source than him, as we dive a specific profile, that will leave us more than enough gas in either cylinder to get us back to the surface.
Where's the option for both on long hoses?
And you'll need 'sorry, I don;t understand, I have a rebreather'
:D
Turtle Dude
08-07-2008, 14:50
Where's the option for both on long hoses?
And you'll need 'sorry, I don;t understand, I have a rebreather'
:D
Apologies. Good point!
Just realised the form cuts short the question text.
Richard Whitcombe
08-07-2008, 15:15
Am interested to know how many people are diving with primary or secondary long-hoses (typically 5-7ft), as advocated by a number of diving groups for out-of-air situations.
I use a long hose and primary donation as i think its a simple effective means. BSAC disagree.
Im not allowed to teach it to entry level but every single dive i do that isnt teaching entry level i use it.
Nigel Hewitt
08-07-2008, 15:44
Used to have a 5 foot hose starting at my left hip.
These days if we're shallow diving I have a pony of air on a normal hose for you cliped to my right side but if we're deep I will pass you my bailout stage and take your part empty one when you signal you are half way down.
Where's the option for both on long hoses?
Why would you dive both long hoses ?
There was an thread a while back (one of those long primary donate arguments that go on and on and on..)
Anyway, it was suggested that two long hoses was useful then it really doesn't matter which reg someone goes for, especially for indi-twins when you'll be breathing from both alternately..
I use a long hose and primary donation as i think its a simple effective means. BSAC disagree.
Im not allowed to teach it to entry level but every single dive i do that isnt teaching entry level i use it.
Just to clarify, but BSAC disagree with primary donation for inexperienced divers. Experienced divers it's fine, and was discussed (pros and cons) when I attended the SMG instructor workshop, with two instructor trainers arguin both sides.
---
Personally, my own order of preference is:
Primary-take
Secondary-take
Primary-donation
Secondary-donation.
For inexperienced divers, I can see why secondary-take is much better than primary-take.
Janos
peterpan
08-07-2008, 23:24
i was taught to donate my octo, but i was already a qualified OD before i ever got to dive with anyone who also donated their octo. before that i
had only dived with people on twins who would donate a long hose or with rebreather divers who would donate a bail out. still on singles now but use a long hose config cause thats what i know and most of the people i dive with usually use the same only with twins. also i find it much simpler and cleaner, but thats prob cause im a product of my teaching. although now i also carry a pony side slung ala stage which i could pass off but in the buddy check i emphasise that its for my use only!
pp
Turtle Dude
08-07-2008, 23:40
Interesting that the majority (so far) are long-hose primary folk. .... I wonder if there is something in it....
Tristan Green
09-07-2008, 02:11
Interesting that the majority (so far) are long-hose primary folk. .... I wonder if there is something in it....
Yeah,
The folks that regularly post on this forum are a very skewed data set when it comes to the real world diving demographic.
Maybe if you could ascertain how many of the option 1 and option 4 voters dive twins, single configuration or rebreather that would show a clear split one way or the other.
Cheers,
Tristan
So, my octopus has a l/h entry reg, which increases the effective length of the hose (since you don't have to put a bend in it to get it the right way round for the receipient) and others have the side vented valves that don't mid which way up they are - so do those count as 'long' hoses for the purpose of this poll?
So, my octopus has a l/h entry reg, which increases the effective length of the hose (since you don't have to put a bend in it to get it the right way round for the receipient) and others have the side vented valves that don't mid which way up they are - so do those count as 'long' hoses for the purpose of this poll?
Probably not. Most people use the term "long hose" to refer to a 2m hose.
Janos
Interesting that the majority (so far) are long-hose primary folk. .... I wonder if there is something in it....
Absolutely nothing.
Most fora have a core of regulars and in the dive world this is dominated
by more experinced divers leaning towards the technical.
To give you an idea a recent poll on YD of "what was the last course you did",
had an almost 50/50 split of standard agencies vs technical.
So any response here will be misleading, as it does not reflect the true
demographic of diving.
To give you an idea a commonly used guesstimate is that 90%+ of diving is
in the recreational range with the use of a standard octopus.
So if this fora was representative, you should have a 90/10 split, not a
majority in favor.
Turtle Dude
11-07-2008, 14:33
I can see that on here we don't have a typical diving sample set, it is probably skewed. I can see and appreciate the advantage/thought behind long-hose primary donation (originally typed "detonation"!).
As I dive however most of the time with lots of different buddies just about all taught with conventional octopus, I will stick to a more conventional set-up for now....
ChristianG
11-07-2008, 14:41
My conventional hoses are octopus length at least, in fact I don't think I own a conventional hose. As well I use a long hose to my primary first stage. Moreover the other/s are always routed underarm.
Electricgahs
25-08-2008, 07:47
I have my primary on a standard hose length, and an octopus on a 2 mt hose...prior to the dive I usually suggest my buddy to grab whichever reg he feels like ( even the one in my mouth) if he is in emergency...
Once we are both cool and relaxed, if he took my primary, I ask him to swap reg so we can ascent easily together.
edwardholmes91
11-03-2012, 06:46
I'm a sports diver and only heard about this hog loop configuration the other week. My configuration is as follows:
BCD hose comes over my left shoulder and drysuit house under my right arm strap to a swivel valve. My gauge come down my right hand side and is clipped in place to my BCD. My main reg comes over my right shoulder (right hand feed) and my octo comes over my left shoulder (right hand feed). The octo is identified by fluorescent yellow Spiro wrap on the hose and it held in place with a florescent yellow holder on one of my BCD d-loops. The reason for the octo configuration is to use it effectively it should be used the correct way up. If someone grabs it from my kit and it is facing the wrong way as soon as its swivelled 180 degrees it should in theory be facing the correct way up.
I have also started using a pony bailout which is for my use only and held round my neck on a bungee.
katyjinny
11-03-2012, 08:16
I have also started using a pony bailout which is for my use only and held round my neck on a bungee
If your buddy takes your octopus do you switch to your pony? Why not do away with the octopus (unless you think you might need 3 of you to be breathing from your cylinders) and just say that the pony is your AAS for your buddy?
Hickdive
11-03-2012, 09:55
If your buddy takes your octopus do you switch to your pony? Why not do away with the octopus (unless you think you might need 3 of you to be breathing from your cylinders) and just say that the pony is your AAS for your buddy?
Because if your buddy needs your AAS they must have been out of air at some point and it is probable they'll be anxious with a much higher SAC. Putting them onto a relatively limited air source when they are puffing away is simply inviting them to have yet another out of air situation on the way to the surface.
Your pony is great for getting you to the next air source, whether that be your buddy's octopus or the surface without any stress or panic but they are less useful for assisting an already-stressed diver because of the limited amount of air they contain.
edwardholmes91
11-03-2012, 11:11
@Hickdive Thanks for your comments, I agree with you there... however you probably explained it a lot better than I would of done! :D I've not had a huge amount of practise with the pony yet, but it is nice to know that that extra bit of bailout gas is there if something were to fail or I was stupid enough to run out of air!
I went diving last weekend at Vivian Quarry in Wales and was quite pleased with my air consumption. Usually I tend to breathe a lot, but I managed an 18m dive for 30 minutes... with 200 bar in 15L and came up with 70 bar! I try to stick to the rule of thirds if I can.
katyjinny
11-03-2012, 11:39
Hickdive Thanks for your comments, I agree with you there... however you probably explained it a lot better than I would of done! I've not had a huge amount of practise with the pony yet, but it is nice to know that that extra bit of bailout gas is there if something were to fail or I was stupid enough to run out of air!
So you're not carrying anything in reserve for your buddy then? Your pony is in case you run out of air? My pony carries 700 litres of totally independent reserve air which is for my buddy. More than enough to bring a sports diver to the surface safely without both of us trying to swap regs.
Have a read of this HSE report on what happens when an octopus is used, http://www.hse.gov.uk/research/rrpdf/rr341.pdf
...and this from your BSAC Safe Diving booklet
Alternate (gas) sources (Air and nitrox diving)
BSAC strongly recommends that all divers carry an Alternate (gas) Source (AS) in the event that they may need to share gas underwater.
Suitable AS include an 'Octopus Rig' (a second 2nd stage fitted to the same 1st stage of the regulator, which includes the type fitted to a direct feed). In this case divers should be aware that a first stage failure on their regulator will affect both second stages and may render them in-operative.
(The HSE report explains why this is more likely to happen with 2 divers breathing from one cylinder.Not in the BSAC doc I've put this in :) )
A more strongly recommended alternative, however, is a totally independent gas supply such as a 'Pony cylinder' (a small 2-7 litre auxiliary cylinder attached to the main cylinder with its own regulator assembly) or separate regulators attached to each cylinder of a matched p
Memory Skills.
You dive a single with octopus, the protocol in a jam is that the OOG
diver will grap the octopus. At best it will be a full cylinder available,
at worse reserve.
You dive a single with octopus & pony, the protocol in a jam is that the
OOG diver will grap the octopus. At best it will be a full cylinder
available, at worse reserve.
If YOU need more gas, you have access to the pony. If YOU have a failure
of your primary, your buddy is nowhere around or are seperated, then YOU
have access to that 3lt pony. Point here is that the pony is NEVER for your
buddy it is always YOUR bailout.
Basic Calcs.
For calculation purposes we usually use 25lt a min as a surface breathing
rate. A seriously stressed diver that has recently been OOG will use
considerably more than that, with factors of x2 to x4 reported.
A pony is rarely used at 20m, more commonly on 30m dives, so working
on that depth assumption the pony would last:
Normal = 9.28 min
x2 = 4.64 min
x4 = 1.74 min
Fastest ascent time from 30m to surface, with no stops = 2 min,
we have no idea as to what the faff time is prior to the ascent.
Looking at the above figures, it makes little sense to put the OOG diver on
the smallest available gas supply.
The bottom line, keep your rig the same and have the same protocols
whether you have the pony or not. The pony is always YOUR bailout,
whether that's when your own system goes bad or if you need to use
it yourself when donating the main to your buddy, either way its for you
alone.
katyjinny
11-03-2012, 13:16
The bottom line, keep your rig the same and have the same protocols
whether you have the pony or not. The pony is always YOUR bailout,
whether that's when your own system goes bad or if you need to use
it yourself when donating the main to your buddy, either way its for you
alone.
BSAC Safe Diving ...
"..allow for the potential need for the buddy to use the diver’s alternate gas source throughout the ascent."
BSAC Safe Diving ...
"..allow for the potential need for the buddy to use the diver’s alternate gas source throughout the ascent."
"..allow for the potential need for the buddy to use the diver’s alternate gas source throughout the ascent."
Yep I can highlight as well ;)
The fubar response in Safe Diving is about picking a range of options
starting with the most common response to the most common scenario and
progressing down the line to less favored and possibly more risky options.
So as an example if your buddy had exhausted the primary, then even
though BSAC no longer teach it, there would be the potential for
Buddy Breathing off the pony. BSAC dont want to highlight these worse case
practices, but then they dont want to create an enviroment where any
option no matter how risky is is dissmissed when it comes down to the wire.
So yes you do need to recognise that there is the potential for
using the donor's AS, but the SDP doesnt say thats its the primary
method, just be aware that it might be a possibility.
Hickdive
11-03-2012, 14:51
It's really very simple;
If YOU have a problem with YOUR gas supply then YOUR pony is to get YOU to the nearest available air. That could be the surface or it could be your buddy's octopus.
If you've planned the dive correctly then your buddy will have enough in their main cylinder to get you both to the surface in a safe, controlled manner.
If your gear is set up so that your buddy uses your pony if they have a problem with their gas supply then the chances are they will use up all of the available air in the pony very quickly. If you do not then have an octopus then they will have the choice of swimming for the surface or sharing (more likely grabbing) your primary.
On the other hand if you have your pony set up for your own use and an octopus off your main cylinder then for your buddy then if you find that your main is getting too low or your first stage is struggling to supply you both then you, as the rescuer, have the option of calmly swapping to your pony; reducing the stress on the first stage and freeing up more gas in your main for your buddy's use.
It's all about avoiding painting yourself into a corner; planning for an OOG buddy to use your pony and not having an octopus on your main supply can leave you without any further options, so I would avoid doing that.
If both divers have ponies set up for their own use and octopusses for their buddy and a gas plan that allows for assisting their buddy to the surface with both divers breathing off the main cylinder then that, IMO, is a safe a set up as you can get without getting into the realms of twinsets, long-hoses, manifolds and such.
Mike Halligan
11-03-2012, 15:03
BSAC Safe Diving ...
"..allow for the potential need for the buddy to use the diver’s alternate gas source throughout the ascent."
I'm afraid that (for me) the pony does not qualify as "the diver's alternate gas source" because it may well not last "throughout the ascent" when feeding an OOA buddy.
Before you ask, yes I have made an emergency ascent from around 20m on my own pony (banging in a 3-minute safety stop on the way) and no I wouldn't offer my pony to an out-of-air buddy. I'd offer my primary, go onto my pony while (s)he settles then as like as not revert to Air2 as we ascend - but only if in so doing I'd not compromise the buddy relying on the remaining gas in my main cylinder.
/ Tin hat ON :D
edwardholmes91
11-03-2012, 16:08
So you're not carrying anything in reserve for your buddy then? Your pony is in case you run out of air? My pony carries 700 litres of totally independent reserve air which is for my buddy. More than enough to bring a sports diver to the surface safely without both of us trying to swap regs.
My pony holds the same amount but as yours... if the person receiving is panicking then they are likely to breathe 700 litres very quickly at depth. In stressful situations surface breathing rate can increase from 25 litres a minute to 75 litres. Multiply this by lets say 3 bars (20m) and they are using 225 litres a minute which might run out very quickly!
If they run out of air, I would abort the dive and they use my octopus... I would then switch to my pony and perform a CBL to the surface with them carrying out any safety/decompression stops if required and the air supply was sufficient. If they wished they could then use my main regulator instead of the octopus whilst ever I was breathing from the pony. That way you aren't inviting a free flow at depth on your main cylinder. Which I might add should have at least 70 bar left in it if you are following the rule of thirds and you get a decent fill. This gives you more air in your main cylinder than the pony. If you have only one cylinder and no pony then you would have to use main regulator and octopus and try to synchronise your breathing so that only one of your breathes in at one time.
From what I have heard and what most people in my club do, a pony is their bailout supply for use by themselves only. Correct me if I'm wrong but I feel my setup is ok in the case of an "out of air" situation?
ChristianG
11-03-2012, 16:28
From what I have heard and what most people in my club do, a pony is their bailout supply for use by themselves only. Correct me if I'm wrong but I feel my setup is ok in the case of an "out of air" situation?
I think you're perfectly correct in your scenario. I do, however, have an observation to make.
I presume your attempt to synchronise breathing so that you breathe in turn is because it used to be the case that two people breathing from one 1st stage was not optimal because one or the other felt that they weren't getting enough gas? That may have been so in the bad old days but I think that modern regs uniformly have addressed this problem. Besides, synchronising breathing with someone breathing very heavily is going to be more difficult (in those circumstances) than it is of being of any significant use.]
Edit/: Incidentally, the "rule of thirds" was developed for cave diving and has no real reason to exist in conventional recreational diving. For example, if I'm having a good time on a dive I'll probably breathe my main tank close to empty, but leave the pony severely alone, deco considerations aside of course. Thus far no-one seems to have minded this. But then, I can't remember when anyone (any busybody?) last checked the contents of my tank at the end of the dive. I think I'd probably be mortally offended. ;) :eek:
edwardholmes91
11-03-2012, 18:31
@ChristianG
Thanks for your reply. The synchronised breathing was just something I heard from a member of the club but I've fortunately never had to do it and wasn't 100% sure on why it was better but I think I'd heard about the first stage not being optimal for two people possibly?
The rule of thirds was just something I was taught in the club as a safety measure and I believe it is on the BSAC syllabus isn't it? When diving with the club we log everyone's dives and air in/out for records. I personally record mine anyway as a means of calculating average air consumption.
katyjinny
11-03-2012, 18:54
Thanks for your reply. The synchronised breathing was just something I heard from a member of the club but I've fortunately never had to do it and wasn't 100% sure on why it was better but I think I'd heard about the first stage not being optimal for two people possibly?
The rule of thirds was just something I was taught in the club as a safety measure and I believe it is on the BSAC syllabus isn't it? When diving with the club we log everyone's dives and air in/out for records. I personally record mine anyway as a means of calculating average air consumption.
Hello Edward. You've said 2 very pertinent things here. "just something I heard e.tc." and "just something I was taught" If someone tells or teaches you something, whatever qualifications they have, always ask why and satisfy yourself that they're talking sense. Don't get set in your ways in diving, it's a dynamic activity and no one knows everything. My experiences have made me decide that using a pony cylinder for my buddy is the way I want to dive. I don't have an octopus.
Hello Edward. You've said 2 very pertinent things here. "just something I heard e.tc." and "just something I was taught" If someone tells or teaches you something, whatever qualifications they have, always ask why and satisfy yourself that they're talking sense. Don't get set in your ways in diving, it's a dynamic activity and no one knows everything. My experiences have made me decide that using a pony cylinder for my buddy is the way I want to dive. I don't have an octopus.
Good for you! I agree with not taking anything on trust. However my experiences[1] have lead me to a completely different conclusion. I think not having an octopus on my main tank is daft. Having an octopus gives me more options [2]. It also means that I can dive without a pony and just use the same set of regs.
Janos
[1] - I freely admit my experiences aren't wide enough to give a statistically significant evidence base, and I treat them with a degree of caution.
[2] - I remember one particular dive where I lost the mouthpiece on my reg -I breathed in water. My first thought was: "That's odd. Regs don't fail like that". Then I thought: "Now's not the time to be thinking about how a reg works. Let's put in my back-up reg. "
Richard Whitcombe
13-03-2012, 15:37
If your buddy takes your octopus do you switch to your pony? Why not do away with the octopus (unless you think you might need 3 of you to be breathing from your cylinders) and just say that the pony is your AAS for your buddy?
Because you are giving a stressed, probably sky high SAC rate diver at most a 3l tank instead of shares in a main tank 3-4 times the capacity.
That and if you're main second stage breaks in some way you're now limited to a 3l tank instead of that nice big and perfectly good one on your back.
With average gas consumptions a 3l pony is going to get one person to the surface from 30ish metres with a normal ascent rate and 3 minute stop assuming a minute or so faffing on the bottom first.
If you add a really stressed diver or other things it wont. A pony really isnt suitable for deco diving or below about 35m.
katyjinny
13-03-2012, 15:48
A pony really isnt suitable for deco diving or below about 35m.
That's why I said it would be suitable for bringing up a sport diver. The OP appears to be a relatively new diver so things should be kept simple for him. When he gets into planning deco dives or deeper diving then he'll have to look at his kit again. Hopefully he'll keep evaluating his kit and configuration if he gets more experienced and adventurous. I still believe that for new divers the fewer things they have to remember the more likely they are to stay out of the incident pit. Keep your reg in your mouth, give your pony reg to buddy if needed and you're on your way up. No faffing about trying to work out who has which of 3 choices of reg and 2 choices of cylinder.
Richard Whitcombe
13-03-2012, 16:06
That's why I said it would be suitable for bringing up a sport diver.
Not always and that's the problem. People have different SAC rates and importantly, sports divers can do deco dives. Ive seen plenty just slap a pony on and start doing 15-20 minutes deco "knowing" the pony will get them out if they run out of air. They rarely if ever do gas planning or bailout gas planning. Its glossed over very lightly in the SD syllabus.
I still believe that for new divers the fewer things they have to remember the more likely they are to stay out of the incident pit.
"My octopus is here, its the yellow one, pull it and its yours" isn't that hard to comprehend. (Then again neither is "My octopus is the yellow one on a yellow hose, its in my mouth but BSAC seem to think so).
Keep your reg in your mouth, give your pony reg to buddy if needed and you're on your way up. No faffing about trying to work out who has which of 3 choices of reg and 2 choices of cylinder.
There is a big problem with that - you have no idea if that pony is going to get the buddy to the surface and what happens if they suck that dry as well? We don't do buddy breathing any more sadly.
You most likely havent done a SAC rate calculation for that particular buddy and its quite possibly they'll have a higher base rate and you and you really have no idea if that rate will double or even triple when stressed.
Even if you know after calculating the pony will get YOU out of trouble from 30m no stop without doing that you have no idea if it'll do that for a random buddy who might grab it.
That's why i don't like restricting them to 700l of gas when there is near 3000 available at times!
Id favour the odds far more on a 12l or 15l tank in getting a high breathing buddy out of trouble than a 3l.
katyjinny
13-03-2012, 16:15
You seem to be assuming your 12l or 15l is full when your buddy runs out of air. Whatever kit people carry if they don't plan properly they'll get into trouble. Like it or not the recommended AAS by both HSE and BSAC is an independent pony and for lots of reasons I agree. I also said the OP should always ask why when anyone tells him anything and satisfy himself that they know what they're talking about. I'd be more than happy to go through my reasons (not just mine btw) with him face to face. A forum does not give a suitable platform.
Richard Whitcombe
13-03-2012, 16:20
You seem to be assuming your 12l or 15l is full when your buddy runs out of air.
Where did i say that? As long as its a 12l and has 50 bar in whatever you've got is going to be more than is in the pony!
If you aim to be out with 50 or as they're now meant to be on thirds, about 75 bar then at any point there is always going to be more gas available for a buddy in the main tank than a pony.
You also have the option is if you know damn well the pony will get YOU out of breathing from that and allowing the buddy to use the octopus on the main tank.
Whatever kit people carry if they don't plan properly they'll get into trouble. Like it or not the recommended AAS by both HSE and BSAC is an independent pony and for lots of reasons I agree.
Actually no, HSE recommend an independent air source that is *adequate* for the dive. A pony is fine for shallow no stop diving however there becomes a time when it simply isn't.
katyjinny
13-03-2012, 16:32
Have you read the HSE report ?
http://www.hse.gov.uk/research/rrpdf/rr341.pdf
It's very interesting
"The results support the view that the preferred system for an alternative air supply is a completely independent gas supply and demand regulator.
12l x 50 bar = 600 litres of air
3l x 232 bar = 696 litres of air
I still believe that for new divers the fewer things they have to remember the more likely they are to stay out of the incident pit.
Absolutely.
So configure the kit so that you get the same response in an OOG scenario
regardless of circumstance.
1. Single cylinder, OOG buddy grabs Occi they go home.
2. Single + pony, OOG buddy grabs Occi they go home.
3. Single + pony, OOG buddy grabs Occi, air gets depleated, donor switches
to pony, they go home.
The OOG diver is the stressed one, not the donor, he/she has been on gas
all the time. So in 1, 2 & 3 the buddy has exactly the same response and
does not have to swap regs, even if the gas starts to get depleated.
Fewer things for a new diver to remember, well in the above its just the one
"grab occi". Cant get more simpler than that.
Have you read the HSE report ?
http://www.hse.gov.uk/research/rrpdf/rr341.pdf
It's very interesting
"The results support the view that the preferred system for an alternative air supply is a completely independent gas supply and demand regulator.
12l x 50 bar = 600 litres of air
3l x 232 bar = 696 litres of air
Its also flawed and has been ripped to shreds on other fora, not least of
which is the assumption that two divers will demand more gas from a
first stage than one. An OOG diver has been known to have a SAC of 100
far in excess of what two divers might put on the same 1st stage.
As for your figures again flawed argument.
The pony has 696 litres of air, but this is a fixed ammount.
The 12l will start with 2784 lts of air and this will of course go down during
the dive, but if we follow the SDP and rule of thirds will leave us on 928 lts
as a reserve. Incidents dont neccesarily happen at the end of the dive, so
having access to the maximum ammount throughout makes more sense then
relying on that minimum of 696lts.
Have you read the HSE report ?
http://www.hse.gov.uk/research/rrpdf/rr341.pdf
It's very interesting
"The results support the view that the preferred system for an alternative air supply is a completely independent gas supply and demand regulator.
12l x 50 bar = 600 litres of air
3l x 232 bar = 696 litres of air
The HSE report says (very roughly):
"if you have the option of using a pony, then use one"
Everyone here is saying:
"if you are going to use a pony, don't get rid of your octopus"
The two aren't contradictory. I'm disappointed that Janos hasn't used one of his favourite phrases, which is something about false dichotomies.
Richard Whitcombe
13-03-2012, 17:10
Have you read the HSE report ?
http://www.hse.gov.uk/research/rrpdf/rr341.pdf
It's very interesting
"The results support the view that the preferred system for an alternative air supply is a completely independent gas supply and demand regulator.
Yes. So where does it say "pony"? That also includes independent and manifold twinsets. In other words, of a size that is suitable for the dive.
12l x 50 bar = 600 litres of air
3l x 232 bar = 696 litres of air
OK if you want to be pedantic and assume you have a 232 bar fill (most of the world doesn't) then 58 bar has the same as a pony. Which is less the 1 minute normal breathing rate for a NON stressed diver. Its such a tiny amount its not worth considering.
Thats also assuming they're not using a 15!
Plus if they ARE on 50-60 bar they certainly aren't going to still be at 30m -chances are they'll be on their stop.
There is no point on a sensible dive profile that doesnt involve people surfacing with < 50 bar or staying at depth until they hit that figure where a pony is going to have more gas than a main tank.
graham nurse
13-03-2012, 18:43
What does PONY stand for? If you do know ask Jack Ingle:D
A pony cylinder should not be a substitute for poor buddy skills.
Graham.
Mike Halligan
13-03-2012, 18:46
You seem to be assuming your 12l or 15l is full when your buddy runs out of air. Whatever kit people carry if they don't plan properly they'll get into trouble.
People get into trouble whether or not they plan. They just seem to get into more trouble more deeply when they haven't planned.
Like it or not the recommended AAS by both HSE and BSAC is an independent pony and for lots of reasons I agree.
No it isn't. HSE said a great deal and made little sense. BSAC recommends a wholly independent source (minimum of a pony) for one's own consumption first and to be used to assist others as necessary. Everyone I have ever met expects to reserve their pony to themselves and to donate either an octopus or (if equipped with another source then maybe) their primary to an OOA buddy.
I also said the OP should always ask why when anyone tells him anything and satisfy himself that they know what they're talking about. I'd be more than happy to go through my reasons (not just mine btw) with him face to face. A forum does not give a suitable platform.
:eek:
me thinks you don't really understand what a pony is for katyjinny.
a pony is MINE. it is MY gas to get ME out of the poo. it could be a 3l pony, a 7l stage used as spare air, it could be an ali 80 doing the same thing. it could be on my back, on my side on my belly. it is mine for my emergancy, not for anyone elses.
a pony is not used in gas planning other than yes it has enough to get me from X depth to the top with Y needed in stops at Z SAC rate.
it shouldn't be used to extend the dive unless it has been factored in (like me last week using a 7l as a bottom stage to max out the gas in my twinset for dive no2) but then your no longer using it as an emergency tank but as a stage cylinder.
its a selfish gas supply but thats what its there for and i love seeing single cylinder divers with them as it shows they are thinking about the risks and about how much .
the main cylinder with a pair of 2nd stages is what the gas planning is done on and is what the OOG buddy should be breathing from. pony for my get me out of here back gas for you.
Richard Whitcombe
13-03-2012, 19:22
A pony cylinder should not be a substitute for poor buddy skills.
Graham.
But likewise a buddy should not be used as a substitute for poor dive skills or lack of self sufficiency/redundancy.
me thinks you don't really understand what a pony is for katyjinny.LOL.
a pony is MINE.You are talking about YOUR pony. Do with it what you will!
My pony is just a flippin 3Ltr cylinder. I don't myself believe it to have any magical ability or special properties, above those of 3Ltrs of gas carried in any other size of cylinder.
the main cylinder with a pair of 2nd stages is what the gas planning is done on and is what the OOG buddy should be breathing from.Once again you are confusing MY with THE. My own preference is to avoid putting two divers on the same first stage, for much the reasons reported by Quiniteq. That choice is reflected in my gas planning.
I am also quite the fan of KISS as a guiding principle, both in terms of equipment configuration and in contingency planing. If you want to carry 3 mouthpieces when two will essentially do, that is absolutely fine. I believe that it is making things more complicated than they _need_ to be. i.e. A strictly like for like comparison leaves the third mouthpiece a superfluous encumbrance, an un-necessary point of failure and requires adaption of core skills to make use of.
No it isn't. HSE said a great deal and made little sense.Mike, HSE said nothing. HSE commissioned the study. The work was completed by Quiniteq, just up the road from me.
I believe the essential pertinent point they were making is roughly as follows.
You have two divers on two seemingly good 1st stage regulators. One of those regulators free flows, the failure being in some part contributed to by environmental conditions (cold water). An octopus configuration forces the OOA onto a single 1st stage, which is subject to the same environmental factors. Should both those divers breathe simultaneously, in phase, concurrently, however you wish to express it. The load on the good 1st stage is effectively doubled. Both divers are dependant on the good first stage being at least twice 'as good' as the regulator that failed, under roughly half the load in the same conditions.
The question raised is, do you want to be doubling the load on your 1st stage while you are trying to sort out a rescue situation? My answer. No.
There is clearly a risk here but it is not one that is quantified by the testing standards. The whole lot of words attempting to cover the difference between good regulators in poor condition, poor regulators in good condition and all points in between. All these regulators could pass tests exceeding the load created by a single diver breathing maximally. Most might pass with two divers breathing out of phase. Some would not pass with two divers breathing in phase, was the observation.
Do you see the duty of care implications the HSE might have an interest in?
Course I might have had a drink when I was discussing this informally with a mate that may or may not have worked for Quiniteq during the time of the trials. So I wouldn't believe a word of it myself ;)
Before you ask, yes I have made an emergency ascent from around 20m on my own pony (banging in a 3-minute safety stop on the way) and no I wouldn't offer my pony to an out-of-air buddy. I'd offer my primary, go onto my pony while (s)he settles then as like as not revert to Air2 as we ascend - but only if in so doing I'd not compromise the buddy relying on the remaining gas in my main cylinder.
BSAC do not recomend primary donate, your reg should stay in your mouth and an alternative supply offered. A full 3l pony will get even a heavy breather up from 20m and possibly 30m as once reg donated you would have taken a firm hold and be on your way up (15m a minute up to 6m). Taking charge of the out of air incident quickley is the key to calm the situation. We all have our own ideas but we should not go away from our training, I have dived for years with a 12l and a 3l pony before changing to twins and now on to a rebreather. I have seen a number of octo's freeflow causing the out of air supply problem in the first place so would not dive with one.
Hickdive
13-03-2012, 21:14
Fewer things for a new diver to remember, well in the above its just the one
"grab occi". Cant get more simpler than that.
I can think of a simpler system but that's a digression we won't go into, again.
Hickdive
13-03-2012, 21:31
I daresay that if I were a rescuing diver and found that my first stage wasn't up to the task of supplying me and my buddy inhaling simultaneously then it is probable that I might not understand the cause of my sudden breathing difficulty.
However, my probable reaction would be to switch to my pony, which would resolve the issue of beating a single first stage for both of us.
Gas planning, as I understand it, would calculate a reserve on the basis of getting myself and my buddy to the surface safely from the furthest point of the dive on my single cylinder. So the question of whether or not that single is full at the start of the dive is moot; the important point being that I plan the dive to maintain a reserve adequate to achieve that. A pony forms no part of that calculation. As I said before, it is only to get me to the next safely available air source, either my buddy with a reserve in their single calculated to support the pair of us to the surface or directly to the surface by myself.
I'm sure 'better buddy skills' is the ideal solution rather than a pony but in the real world I think I'd rather pop my pony regulator in my mouth and breath than drown whilst thinking, 'tsk, tsk, if only me and my buddy were better divers'.
Mike Halligan
13-03-2012, 22:14
In 2005, HSE applied its covers to work done by Qinetiq, Breathing Performance of 'Octopus' Demand Diving Regulator Systems. This work is implicated by an undated Divernet reference which alleges "HSE recommends the use of a completely independent secondary gas supply system, for example a pony cylinder set-up,' said Chris Sherman, Chief Inspector of Diving. 'That way, if there is a problem with the octopus system or if a buddy pair become separated, divers have a much increased chance of survival in the event of running out of air."
This (Divernet) may be source of the confusion.
I daresay that if I were a rescuing diver and found that my first stage wasn't up to the task of supplying me and my buddy inhaling simultaneously then it is probable that I might not understand the cause of my sudden breathing difficulty.The point being made is that doubling the load on the rescuer's 1st stage may cause it to freeflow. i.e. The act of sharing the 1st stage is the cause of the failure. The rescuing diver can switch to their pony but they still have two free flows and an OOA diver on their hands.
Gas planning, as I understand it, would calculate a reserve on the basis of getting myself and my buddy to the surface safely from the furthest point of the dive on my single cylinder...A pony forms no part of that calculation.There is more than one way to calculate gas requirements.
Someone diving with a pony routinely might decide the pony is the limiting factor. Depths, times and minimum fill pressures can then be calculated to fall within the furthest point that the pony is expected to be able to return a buddy to the surface - The minimum volume of gas reserve we are advised to surface with intact in the main. In this case the pony is a redundant reserve, a part of the gas plan and who might breathe it becomes a non-issue.
Despite the dodgy maths going on, a 3Ltr pony is (still) 1/3 of a 10Ltr, 1/4 of a 12Ltr and 1/5 of a 15Ltr. The first fraction (1/3) is what BSAC recommend as the reserve that should be left intact on surfacing. The second (1/4) is what a relaxed dive supervisor might think reasonable to accept. 1/5 is stretching it, perhaps a little too far, particularly in view of the increased duration of the main supply.
Hickdive
14-03-2012, 11:49
The point being made is that doubling the load on the rescuer's 1st stage may cause it to freeflow. i.e. The act of sharing the 1st stage is the cause of the failure. The rescuing diver can switch to their pony but they still have two free flows and an OOA diver on their hands.
Er, no. The point being made (and it's right there in the Executive Summary of the at the top of the HSE paper) is that two divers breathing off the same first stage may cause the regulator to fail to meet BS EN250 i.e. not provide enough breathing gas to meet that required standard. A diver at work in the UK (and therefore required to meet HSE ACOPS) has to have breathing apparatus that meets BS EN250 at all times, whether they are in a normal diving situation or dealing with an incident where they have to supply air to another diver. I said nothing about freeflow and indeed the HSE paper says nothing about freeflow.
There is more than one way to calculate gas requirements.
Someone diving with a pony routinely might decide the pony is the limiting factor. Depths, times and minimum fill pressures can then be calculated to fall within the furthest point that the pony is expected to be able to return a buddy to the surface
And the point I and others have made is that such planning backs you into the corner of leaving you with no options to deal with the pony developing a problem.
The minimum volume of gas reserve we are advised to surface with intact in the main. In this case the pony is a redundant reserve, a part of the gas plan and who might breathe it becomes a non-issue.
And if that reserve in the main cylinder is calculated to support both divers to the surface from the furthest point of the dive then the pony is genuinely a redundant reserve rather than the only reserve.
ChristianG
14-03-2012, 13:24
I can think of a simpler system but that's a digression we won't go into, again.
;) :D
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