View Full Version : Gas shutdowns
Ok here's a vid of a diver on technical diver training, he's at about 36m and the water temp is 5 degrees.
He's practicing shutdown drills, he has two buddies there and between them they have *LOADS* of gas. So it is effectively the perfect time to have a free flow, conditions will *never* be easier and he *knows* that even if he loses all his gas he's still ok. So no pressure then...
Now watch how long it takes to shut down, even with his buddy closing the valves for him :(
Now, if you dive a single cylinder ask yourself how close your buddy normally is, and if you dive twins, be honest, and think whether you could really do a shutdown any faster, in the dark, can't see anything for bubbles anyway, probably starting to sweat, if not panick because you know you're watching very large amounts of gas go past your eyes.... this is why I hate conventional "upright" twins when they're manifolded (and manifold is open).
A good time for all of us to try a "practice" shutdown and then change whatever doesn't work.
Stay safe down there!
Tp22x74SyEc
http://www.youtube.com/watch?v=Tp22x74SyEc
Mmmm, so do you invert them Smudge ?
its not smart to dive twins & not be able to isolate them.
it's just the same as diving a single cylinder.
what length are you reg hoses on yer inverts :confused:
Mmmm, so do you invert them Smudge ?
:D funnily enough....
Joking aside, I tried "conventional" twins, and discovered I couldn't reliably reach the valves, so I asked more experienced divers and an alarming number whilst saying "yeah it's easy I just have to swing my arm like this.." and performing acrobatic contortions were clearly struggling to reach their valves. Comedy for me but scary when you think about it. As a result I dived isolated for a while and after a lot of looking about and thinking tried inverting mine. It's still not effortless... but I can reliably reach my valves quickly, every time, whatever way up I am ( :eek: )
I'm not saying it's the best or only way but I do think people should consider it. I had a free flow a while back in about 12m and decided to just breathe the cylinder to the surface as an exercise (buddy was close by and the other half of my twin tens was isolated). in the time I took for the ascent (not more than a couple of minutes) I pretty much emptied the cylinder, there was a reserve left in it when I shut down on the surface, but that was all...
Had we been at 20 / 30 / 40metres it would have emptied long before the surface.
Good exercise if you ever get the chance, I discovered you can't hear a computer ascent alarm(Aladins bleep early, my ascent was ok ;) ), it's difficult to see your buddy and also difficult to see your computer for all the bubbles. Pretty stressful just because of the noise and limited vision actually, oh and the bubbles can dislodge your mask if you're unlucky so you get to add holding that / clearing it to your list of tasks.
I'm probably a worrier or a bore but it scares me when I look at twinset divers kitting up for relatively serious dives and looking at how (im)mobile they are I'm 99% certain they can't reach their valves :( Some can, I know. But too many cannot.
As Stewart says, diving manifolded twins that you can't isolate is diving a big single, and the only loser will be the diver doing it, or their friends/family of course :(
Anyway, all that's just my take on it. I'm advocating an option not a DIR mantra ;) and as I've said to others, if you're ever in the water with me feel free to show me a slate saying "gas shutdown now" or "Freeflow your main reg. Fix!" and we'll see how I do :eek: :D
Personally I think that should be done (the slate thing) periodically by buddies to each other anyway and to any diver of any grade. No warning, just a real time practice during a real dive but while your buddy is close in to ensure a safe drill. After all, the the bad things generally don't happen when we're on a course and in the "drills" mindset ;)
(and I have seen a single and pony diver failing miserably to find their alternate reg when asked to so they can get it too :p )
Sorry for being morbid! Safe and happy bubbles all (except for the RB divers who of course don't want to see bubbles :eek: ;) )
what length are you reg hoses on yer inverts :confused:
I dive with a standard octopus hose on my alternate, it's mainly for me but a buddy can use it if they are a little lower than me. My main is a long hose, can't remember the length but it is an off the shelf one, wraps round and comes over my right shoulder. That's the "donating" hose and theres plenty to give a buddy a comfy length of hose.
I dive a Custom Divers wing and the direct feed inflators are again off the shelf, I'd need to measure them to give you a size but CD keep them in stock as so many people apparently ask for them, they run up between the cylinders and the wing before exiting over the shoulders.
The main downside is that the top is so uncluttered and clean there's nothing at the top for people to lift it onto the boat so I normally turn it over so they can lift on the cage. Rescue drills are no prob as a rescuer can easily grip the shoulder straps (we discovered during drills :) )
good topic for discussion Smudge!;)
i dive twin's (10's & 12's) which are standard manifolded.
i used to dive independents, but i think manifolded is IMHO safer & more practical.
i can reach my valves, much easier on the 12's than the 10's but i can reach them all the same.
i must admit, i used to have difficulty shutting them down so a little regular practice goes a long way, you never know when you might need to do it for real.
pro's & cons for all 3 setups (none are full proof), its a matter of experience, choice, safety & what type of diving your doing.
interesting topic i ,m not in technical depths meaning non deco i dive with a 15 and a pony my pony reg is on a neckless my alternate is an auto air i have a new buddy commando bc . i found doing the md training shares and ascents .helped iron out any kit probs . i,ve had this sort of conversation about emergencies with a few people at my club .some even moan about the weight of my kit . lifting it into the boat.its the attitude of some people about diving with a pony .i don,t get the pony is a totally redundant supply as far as i am concerned . if my main set is nackered i still have air to either assend safely or get to my buddy with time to sort ourselves out. its the ive been diving for years and never had a problem i find worrying . our b.d.o wants everyone in the club to practice emergency drills at least once a year . not much i know but it might wake some of the complacent ones up.
Good topic indeed.
Most of my buddies dive twins but to be honest we don't practice shutdowns.
With my old neoprene suit there was no way I could reach the valves, it was a touch to short for me and didn't give me enough "give" to get my hand behind my back. This was the reason I got a new suit.
I had a wee incedent after my instructor isolated my tanks in the pool and didn't tell me. I found out on my next dive :eek: Now I know I can reach my valves ;)
I'm not sure about inverting though. Just suppose you found yourself in a confined space (every heard of the diver who decended down a funnel? :eek: ) Generally speaking, when horizontal, you will have your hands in front of you (raised when standing). If you where to find yourself in a confined situation and are really unlucky to have a free flow you may not be able to get your hands behind you again (lowered when standing). Where as if your cylinders where mounted "normally" you could still deal with the free flow.
Having read Lizardlands website he seems to have strong thoughts on inverted twins but doesn't explain why. Would be interested to hear your thoughts Stuart.
I'm not sure about inverting though. Just suppose you found yourself in a confined space (every heard of the diver who decended down a funnel? :eek: ) Generally speaking, when horizontal, you will have your hands in front of you (raised when standing). If you where to find yourself in a confined situation and are really unlucky to have a free flow you may not be able to get your hands behind you again (lowered when standing). Where as if your cylinders where mounted "normally" you could still deal with the free flow.
Having read Lizardlands website he seems to have strong thoughts on inverted twins but doesn't explain why. Would be interested to hear your thoughts Stuart.
Personally I would have thought that in most confined situations your hands are in front in the chest / waist area and it's relatively easy to slide them round the side to the small of your back, needs much more room to reach up and over, but that depends on the diver and the particular gap. If however we're talking about a space so narrow you have to wiggle through it then maybe it's time to isolate *before* you enter the narrow section, and indeed to consider whether it is wise to enter such a confined space :eek: I'll confess, I am not, and never will be a cave diver ;) on wrecks, in my experience, any gap that narrow should be viewed with the gravest suspicion at best!
Of course having the valves/hoses etc where you can get at them makes unsnagging considerably easier too.....:p
I shall have to have a shufti at Stuart's site, as I've said in the past, it's entirely possible that I am wrong on many many things and I will always try to listen to other divers experience and opinion. :)
Having read Lizardlands website he seems to have strong thoughts on inverted twins but doesn't explain why. Would be interested to hear your thoughts Stuart.
lol, just had a look and I suspect we will have to agree to disagree :D but then Stuart is clearly doing a lot of cavediving and as I mentioned, I dont!
To save anyone else a search his thoughts on Custom Divers Kit and inverts can be found here:
http://www.lizardland.co.uk/ under "EQUIPMENT -- BAAAD!!!" ;)
Personally I have to say I find CD kit has (so far) been way more robust and suited to my sort of diving than most dive kit I've had the misfortune to buy/use. I bought mine (mis)used and I was able to buy all the spares I needed easily and with good service. Clearly that's not been his experience.
As to the inverts being good for firefighters and naval divers... what, those guys who work in enclosed spaces and nil viz....? ;) I've thought about it, and the hazards of both systems are obvious :) I've actually never seen inverting seriously discussed in a dive mag, they're normally too busy trying to peddle this weeks dive computer/overpriced fins or reminding us of "safety lessons" which were covered in basic courses, but I digress. There's a lot there that I wholeheartedly agree with, and a lot I don't. If we were all the same life would be dull.
What I think we probably DO agree on is that everyone should try to *think* about their diving, their kit and their failure plans. (hopefully not putting words in your mouth Stuart!)
Imho one particular kit combination, be it DIR, or a single and stab, or something like mine, cannot possibly suit all sorts of diving and all sorts of divers. Look at them all then choose what best suits *your* diving.
Sorry all for rambling on like this :eek: I seem to have slipped into writing a small book :confused:
I can just reach my valves when set up with valves at the top, but set up inverted last night and it's so much easier. Ordered a Ria-Tek guard last night (Website price is wrong, Ivan emailed me back a price of £36 delivered) and will get longer BC hose made and probably ge 1.5m on back up reg and then try it all out in the water next week.
http://www.ria-tek.co.uk/
What I think we probably DO agree on is that everyone should try to *think* about their diving, their kit and their failure plans. (hopefully not putting words in your mouth Stuart!)
Imho one particular kit combination, be it DIR, or a single and stab, or something like mine, cannot possibly suit all sorts of diving and all sorts of divers. Look at them all then choose what best suits *your* diving.
Sorry all for rambling on like this :eek: I seem to have slipped into writing a small book :confused:
You've hit the nail on the head there. Diving is not a sport to be following fashions. You really need to fully understand your set up. As you say it may not be to everyones liking but it is what suits you.
At the same time though I think it pays to have some level of standardisation. It's all well and good having a gear setup that you understand fully but do it too differently and it could cause problems underwater. I know we all do buddy checks before we jump in but if you're diving with somebody new and the brown stuff hits the fan at 30m are you actually going to remember each detail of the buddy check? Your narked buddy might take a bit longer to figure out that your tanks are upside down (;)) at the very least waste some valuable seconds automatically going to the top of your tanks.
I know you would have shut them down yourself by this time but you never know......
(I love this big spoon :D )
Lizardland
28-10-07, 13:08
I'm not sure about inverting though. Just suppose you found yourself in a confined space (every heard of the diver who decended down a funnel? :eek: ) Generally speaking, when horizontal, you will have your hands in front of you (raised when standing). If you where to find yourself in a confined situation and are really unlucky to have a free flow you may not be able to get your hands behind you again (lowered when standing). Where as if your cylinders where mounted "normally" you could still deal with the free flow.
I always close my isolator before I go in anything tight. Dealing with a freeflow or out of air in that situation is very hard. At least if something does happen then even if you do nothing, you've still got half your air to get out with, even if it's just out into somewhere you can start air sharing.
It's important to remember to open it again once you get out of the confined space, it's also important to check the cylinder valves as these can be rolled off (I've had it happen a couple of times).
Having read Lizardlands website he seems to have strong thoughts on inverted twins but doesn't explain why. Would be interested to hear your thoughts Stuart.
:rolleyes: I knew I'd get pulled up for that one day... :D
I, personally, for me, don't like inverted cylinders. For a number of reasons (in no particular order):
- the valves are the heaviest end of the cylinder and it's better for trim having them high up
- if you don't have a stand then you've got your entire set resting on the valves when you're kitting up. When you sit down that's a lot of weight coming down on them.
- if you do have a stand then it's crying out to get crap round it
- when I tried them I found that stage bottles (especially ally stages) got in the way of working the cylinder valves
- you need a longer long hose to get the same air sharing position as a normal set i.e. you're effectively losing 750mm of hose length. That might not seem important but if you are, say, on a wreck penetration then you want the out of air diver in front of you. That reduced length could cause problems.
- extra length hoses needed for wing
lol, just had a look and I suspect we will have to agree to disagree :D
Fair enough :)
Personally I have to say I find CD kit has (so far) been way more robust and suited to my sort of diving than most dive kit I've had the misfortune to buy/use. I bought mine (mis)used and I was able to buy all the spares I needed easily and with good service. Clearly that's not been his experience.
Maybe they are better now, I tried CD kit when they first started out and hated it. I've always found it a bit over-priced and not as well thought out as other makes. Anyway...
As to the inverts being good for firefighters and naval divers... what, those guys who work in enclosed spaces and nil viz....? ;)
My point being they use inverted cylinders for different reasons and they are also working within a tighter set of rules/procedures than us.
I've actually never seen inverting seriously discussed in a dive mag
IIRC it was discussed a lot in the mid-late 90's. Richy Stevenson wrote a very good article on the pros & cons (emphasising the cons) in an early edition of 9>90.
What I think we probably DO agree on is that everyone should try to *think* about their diving, their kit and their failure plans. (hopefully not putting words in your mouth Stuart!)
OK, Ill agree with that if I have to :) The number of people with "naive", to say the least, emergency procedures is shocking. There are a lot of people out there who are lulling themselves into a false sense of security.
Imho one particular kit combination, be it DIR, or a single and stab, or something like mine, cannot possibly suit all sorts of diving and all sorts of divers. Look at them all then choose what best suits *your* diving.
I disagree up to a point, I think DIR is one of the few systems that does actually work in the vast majority of settings and works for most people. If nothing else, it removes all the fannying about trying out different stuff.
Anyway... I can't talk, I dive inverted 3's :D
http://i113.photobucket.com/albums/n233/lizardland/HPIM0533.jpg
Anyway... I can't talk, I dive inverted 3's :D
http://i113.photobucket.com/albums/n233/lizardland/HPIM0533.jpg
:D lol Now *that* is a better looking setup ;) if I'm not being confused by the pic, is that a KISS? Looks like it to me and if so then we can certainly agree about CCR rebreathers :D Well, agree that you dive the one I'd like :rolleyes: :)
Lizardland
28-10-07, 15:42
:D lol Now *that* is a better looking setup ;) if I'm not being confused by the pic, is that a KISS? Looks like it to me and if so then we can certainly agree about CCR rebreathers :D Well, agree that you dive the one I'd like :rolleyes: :)
Yep, it's a KISS. I've just had a week's diving without going near a compressor :D best bit of kit I've ever bought.
<envy> lol I enjoy diving my Dolphin but lust after a Classic KISS once I clear my credit cards / win the lottery / get a retirement lump sum* :D
*whichever comes first :eek:
:D
just out of interest, if you have a large frame like the one here
http://www.ria-tek.co.uk/
at the base of your cylinders....
how practical is it to isolate the center manifold?
never dived inverted myself, but this looks awfully tight to me.
Certainly on mine it's easy to grab the cage to twist the set if needed and having the isolator pointed at your.. erm, butt, is surprisingly easy to reach.
I use a custom divers cage that I blagged for free ;) , (surprise :rolleyes: damn I hate being predictable) hopefully there is a link below. it also has the open side towards my body, you have to work *really* hard to get a line snagged in there!
http://www.simplyscuba.com/xxGetImage.aspx?StockID=7679&ImageNumber=1
so no more difficult than a trip to the toilet then ehh!! :D
Well, if you can scratch your a**e... ;)
As a military diver we do use inverts.. and the reason is that YOU can reach the valves easily.. there are problems.. mainly that the cylinder rests on the pillar valve so you need to have some sort of protector but that is pretty much it.. if you are going to the effort of inverting a protector is essential.. if you look at any set up where you need to get at the valves easily (Eg Rebreathers) the valves are at the bottom where it easier..
pillar valves at the top are from the days of twin hose where they needed to be then.. it is also easier to teach novices when they are using singles at the start and then it is not that important anyway.. you never isolate a single.. UNLESS you are a very special child and do not want to live forever.
saying that it is not the best set up for every one.. but more often than not i hear it getting slated usually by the people who would most benifit by using it.. (thats not aimed at you lizzardland). people should try it THEN they can slate it
I had my 12's in the water for the first time on Saturday and couldn't quite reach the valves. I had and extra layer of thermals on that had a noticable effect on my flexibility as well as the valves being that bit further away than the 7's.
I wouldn't mind sorting out my undersuit to improve my flexibilty before going inverted.
Must say I liked diving the 12's.
Lizardland
05-11-07, 01:14
if you look at any set up where you need to get at the valves easily (Eg Rebreathers) the valves are at the bottom where it easier..
Very true.
saying that it is not the best set up for every one.. but more often than not i hear it getting slated usually by the people who would most benifit by using it.. (thats not aimed at you lizzardland). people should try it THEN they can slate it
Very good advice. Too many get bogged down in one way or the other and won't even consider anything else. I tried inverts, they weren't for me.
I had my 12's in the water for the first time on Saturday and couldn't quite reach the valves. I had and extra layer of thermals on that had a noticable effect on my flexibility as well as the valves being that bit further away than the 7's.
I wouldn't mind sorting out my undersuit to improve my flexibilty before going inverted.
Must say I liked diving the 12's.
A few things that helped me when I went from 7's to 12's:
- get the bands as high up the cylinders as possible if you are using a standard backplate. The top band needs to sit right on the point where the cylinder starts to curve. It's tempting to keep the valves sitting high up but it's counterproductive, it actually moves them out of reach.
- get someone to go behind you and guide your hand. One of the big problems is just knowing where to reach. Most people usually have enough stretch to reach them but it takes time to build muscle memory. Have someone grab your wrist and put your hand on your valves.
- avoid harnesses where the straps cross behind your neck, they really cut down your movement. Some older Dive Rite harnesses do, I think some OMS did as well.
- if you aren't using a standard backplate then get one. Soft wing BCD's like these: http://www.apeks.co.uk/images/products/nx3000.jpg make it a lot harder to reach valves. When you reach behind you then the harness lets the valves tilt away from you.
Probably not ideal but I find exhaling also gives me a bit more stretch.
Cheers,
Stuart
- get someone to go behind you and guide your hand. One of the big problems is just knowing where to reach. Most people usually have enough stretch to reach them but it takes time to build muscle memory. Have someone grab your wrist and put your hand on your valves.
I noticed this with the 7's. The valves aren't where you expect them to be :(
- avoid harnesses where the straps cross behind your neck, they really cut down your movement. Some older Dive Rite harnesses do, I think some OMS did as well.
:confused: Isn't that what single piece harnesses do?
- if you aren't using a standard backplate then get one. Soft wing BCD's make it a lot harder to reach valves. When you reach behind you then the harness lets the valves tilt away from you.
Good point. The top half of mine is soft, it will allow the "backplate" to bend away from the valves.
Probably not ideal but I find exhaling also gives me a bit more stretch.
I dare say if your air packs out :rolleyes: :D
Lizardland
05-11-07, 11:04
:confused: Isn't that what single piece harnesses do?
Nope, on a single piece the strap which comes out the left slot goes over the left shoulder and vice versa. On some fancier harnesses they crossover behind your neck i.e. the strap coming out the left slot goes over the right shoulder. It's really restrictive, it reduces neck movement and stretching. Looking at the photos, Dive Rite have fixed it, not sure about other harnesses though.
Cheers,
Stuart
Nope, on a single piece the strap which comes out the left slot goes over the left shoulder and vice versa. On some fancier harnesses they crossover behind your neck i.e. the strap coming out the left slot goes over the right shoulder. It's really restrictive, it reduces neck movement and stretching. Looking at the photos, Dive Rite have fixed it, not sure about other harnesses though.
Cheers,
Stuart
I see said the blind man :D
Some good reading and sound advice
from experienced divers,
newbie with twin 10's.
thanks
I was starting to panic for that poor guy just watching the video.
Didn't look like a very nice situation to be in!
Nope, on a single piece the strap which comes out the left slot goes over the left shoulder and vice versa. On some fancier harnesses they crossover behind your neck i.e. the strap coming out the left slot goes over the right shoulder. It's really restrictive, it reduces neck movement and stretching. Looking at the photos, Dive Rite have fixed it, not sure about other harnesses though.
Cheers,
Stuart
Caught one.... (http://cgi.ebay.co.uk/Buddy-Wing_W0QQitemZ170165403670QQihZ007QQcategoryZ16053 QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)
This is a good article on setting up a backplate and harness. I followed this just wearing what I'd wear under my drysuit and it worked fine for me.
from Peter Steinhoffs site
http://dir-diver.com/en/equipment/backplate_adjustment.html
Disclaimer/ copyright thing for posting.
Translations
If you want to translate any of the stuff here on dir-diver to post on a local forum or something else, please feel free to do so. I would appreciate if you put my name in there as well as a link to http://dir-diver.com . And please send me the result so I can add it here and everybody can use it!
Scuba-Doh!
07-11-07, 13:33
This is a good article on setting up a backplate and harness.
Certainly is a good article. I just got my Custom Diver TDB (off fleabay, where else) so this was perfect timing for setting up my harness.
Disclaimer/ copyright thing for posting.
Way I read that it was for people copying the article across to other websites and not necessary for just a link. Better safe than sorry though.