RF3.O - Rebreathers: Overcoming Obstacles in Exploration

so I'm going to talk about for a slightly shorter period of time now where can we go on rebreathers that we can't go on open circuit and yes talk about so I've been diving just a little bit about me probably most of you donut don't know me that's my first trip to Florida I have two lives one life I'm an anesthesiologist and work in diving and hyperbaric medicine the other job that I'd like to be doing is going cave diving and taking movies and photographs for large amounts of time I've been diving for about 30 years but my passion for diving has really taken a new hold with the innovation of widely available rebreather technology so what we're going to talk about is how rebreathers work in exploration diving and exploration usually involves an expedition to go somewhere an expedition is defined as a journey that's undertaken by a group of people with a particular purpose for example an expedition into the jungles of the Orinoco there's a second shorter definition which is that it can be a short trip made for a particular purpose like a shopping expedition like we did yesterday to the outlet malls now anyone who believes that to be the correct definition of the term should immediately leave the auditorium by definition expeditions involve some added problems and complexities they're in by definition remote locations they're often hard to get to it may be difficult to communicate to the outside world from remote locations which needs is it means there's a great need for self-sufficiency when you're in these locations and that covers all aspects of what you're doing there including you know living and sleeping and eating and cooking but you need to also think about medical problems and disaster management planning how you're going to get a sick or injured diver out of the site should that become necessary transportation into some of these locations which I'll go on to show you is often difficult as well and often we have to travel very light particularly if you're using things like helicopters which you you tend to pay but by the minute as you're going into the sights now this was the first video which I'll reenact now this is a helicopter flying into the Pierce resurgence and landing by the beautiful river there you get an aerial view looking there's a cargo net underneath the helicopter look there it goes they're dropping the rope from underneath can you see that yes and you'll see us unloading all the equipment four or five tons of equipment into a remote New Zealand River did you get a sense of that these are some of the places in in Australia where we're actively cave-diving at the moment the colours are all strange are they yes colours are all wrong so that's a big brown country called Australia with red circles on it and a little yellow dot where I live the big red circle which may appear to be a slightly hypoxic bloodstains blue color is the Nullarbor plain and what I was going to come and cunningly do with the next slide is show how Florida this amazingly beautiful caves how this is going to now with this video slide you can see florida florida up in the top right corner that is going to magically fly down and fit almost exactly into the Nullarbor plain now the point of that slide is to say that Florida which has a population I gather of close to about 20 million people which is roughly the same as the the Australian landmass about 20 million covers an area of about 66,000 square miles and the nullable plane is roughly the same size it's about 77,000 square miles and has a population but tried to add up the people in the in the few towns there and I got to about 350 people but there must be a couple of thousand people living there out and about but the point being that not only is it a very rich area of for cave diving it's the largest limestone slab in that single slab in the world in fact but it is truly you get a sense of rural isolation when you're out there because you're in the place the size of Florida with that so you may be aware we may not even get to talk about rebreathers at this rate but you may be aware that between Australia and New Zealand there is a little bit of very friendly rivalry and I've it's sad to say but it's true to say there are there are many fantastic things that have come out of New Zealand at the top of the photo there is a long-distance caliper called far lap which is widely recognized certainly down our way to be one of the greatest race horses of all time all my life I thought that was an Australian racehorse until I started doing some research for this talk Ernest Rutherford one of the grandfather of a nuclear physicist at the top left he actually came from a little town called Nelson which is one of the great caving areas of the South Island of New Zealand also I thought he was in Australia until recently I'm still not convinced that the pavlova that meringue and cream filled cake on the bottom right I'm sure that's Australia but Wikipedia and all these sources tell me that it was invented in New Zealand and so on it goes so for forever we're trying to claim all this Kiwi stuff as their own but there is one exception all right rebreathers and the talks nearly finished we're mainly here to talk about safety and I of course take all that stuff very seriously it's important though to look at the other end of the envelope some of the stuff the stuff that we're doing on rebreathers which is arguably not as safe as it could be but to find the limits or the envelope of rebreather diving is actually very important to know because it tells the rest of us what we can safely achieve on rebreathers in the same way that open circuit divers like to swim down a shot line and pull off a peg at the deepest point and return to the surface we're extremely high risk their lives whilst most of us would think that a foolhardy and reckless endeavour it gives us some very important information about what the limits of such diving is and I would never encourage anyone to attempt depth records or or records of any kind for a record sake just to look back though when when rebreather diving perhaps first started from a technical diving point of view I think from what I can understand that probably an oxygen rebreather diving wookie hole was the first technical rebreather diaper formed recreational rebreather dive and unfortunately probably also the side of the first rebreather death but it was a lot easier than walking through those sums in standard dress I imagine I'm very glad that I got a moment to say hello and introduce myself to bill stone and Richard Paul at lunch time before I started to talk about them and and their contribution to this to this sport but in fact this rebreather the the prototype cislunar and everything that followed really did change the way I think the world has looked at rebreather diving and richard has contributed you know equally significantly to that and to their credit both those guys have published so widely about what they've done with these units that we've all got to hear about it and learn about it and certainly this this stuff was what brought we breather diving to my antenna tension and are voraciously read everything I could about bill stones endeavors in particular being interested in cave diving and just to remind you what bill did and with the unit and I hope I don't misrepresent him at all but at a point where they were exploring this very deep dry cave and had reached a sump they had also reached the limits of open circuit diving with the very lightweight high-pressure composite cylinders that they were carrying and you can imagine carrying you know scuba equipment down you know 1,400 metre dry cave involves a massive manpower and massive logistics so when you finally get down to the sump you want to have every opportunity to do the maximal amount of exploration and they'd reach the limit of what they could really sensibly carry down to the sump and start diving so bill built this amazing rebreather which was fully redundant in redundant with its systems and they went on to successfully explore that some and six hundred meters of their exploration was through a some the depth of around 30 meters and the longest dive over an hour and a half and the amazing thing about that whilst that dive in itself is not so spectacular apart from the location of the dive is that only you know 1400 liters of oxygen in about two and a half thousand liters of heliox were consumed which is absolutely nothing a couple of cylinders worth and I think this should be compulsory reading not just for rebreather divers but for all scuba divers because of Bill's ability to take an engineer's approach to look at failure points and failure analysis of complex systems like this and presumably is this thought process to design and build redundant or jewel redundant rebreather system now this these nodal probability schematics where he looks at each failure point along the way and if one thing fails is there a way around it this is my doctor's sort of understanding of an engineering principle he applies in this paper to every type of scuba apparatus including a single thanks Gerber through the manifold it's Gruber's and scuba tanks and so forth now I myself was an engineer of note and like bill I took to building rebreathers in my shed also and this was the Harry Bri that Mark - which was made from a variety of components from the hardware store some stolen and aesthetic equipment and the drag array which is as we all know the home builders friend and that that performed two to three swimming pool dives before it was dismantled and individual components hidden in various parts of the house so that it could never come together and act as a complete machine again but I feel that probably Martin Parker's inspiration was somewhat inspired by this unit and you can probably see the design features that are that are similar and Rick Stanton takes this sort of endeavor to to another level again with his beautifully named hardware store at I like the bagpipes of doing doom and the another one that's called the wing and the prayer and actually a one thing I want to have a talk to Bill about is if he had his time again in that Mexican cave would he take something more like this because he could probably put ten of them in one bag and take them all down with him or what do you still use a complex and a fully redundant system like these something like the kiss rebreather I think has changed the way that a lot of us might think about that kind of exploration I'll have to wait till we're at the bar tonight to ask him so just to look at some numbers what what have people achieved on rebreathers and when I say achieved I mean how far down if they have they gone so this information is all from the internet so please sing out if I've got some numbers wrong or if there's something that can be updated but the deepest cave on rebreather at the moment was the the rebreather David David Shaw performed in Bushman's hall in South Africa as we all know the subsequent dive to the same depth had a fatal outcome there was a recent shot line dive in I think was in the Red Sea by Christoph star now ski using twin hammerhead rebreathers dual hammerheads 283 meters the longest cave traverse in this part of the world as you all know on on a passive semi-closed rebreathers by the WK PP team over 11 kilometres and a massive duration underwater using habitats for decompression the longest sump is now this amazing something Pazuzu in Spain done by the British cave diving team with John Blanton and Rick Stanton and Jason Millicent which is over five kilometres for a single some the deep the deepest sump ever passed to air which is actually an incredibly challenging thing to accomplish if you think about you're going down down down and then get to 100 metres and you start going up and you're having to do decompression at some point you have to commit yourself to keep going up and then basically repeating the whole dive if you don't reach air or if you do reach here you've got to go out to the surface so the deepest some to be passed is about 100 metres which is the first of four Sampson that cave has now been passed and the deepest record of the Milano 236 meters on rebreather so it seems that the 200 meter range is the range whether we're the deeper dives have been done at this stage and there's no question that the risks to the individuals increase exponentially at these at these depths so one question I'm going to ponder towards the end of this talk is you know what what is the current depth limit and where will this finish up so to just look at a couple of the expedition's that I've been involved in over the last few years most cave divers around the world has probably heard of cockle bitty cave it's certainly our most famous cave it's kind of analogous to ginnie springs in terms of how how popular it is to visit or to think about at least it's out on that nullarbor plain that I showed you on the on the method on the Big Green map of Australia and it's certainly a very remote place nullabor as you probably know stands for no trees and it's there's no question that it's appropriately named that's Craig challenge standing over a star dropper which marks the first air chamber which is about eight hundred meters which is about three thousand feet into them okay so there's three stumps basically with two air chambers in the middle and an overall length of about six kilometres orbit over six kilometres it's a very beautiful place despite the fact that there's absolutely nothing there and it's like a big brown billiard table I find the Nullarbor an extraordinarily attractive and beautiful place especially at night time when you get these amazing electrical storms or beautiful sky with all the stars now this to me summarizes why you can do things with open circuit but you don't you know you no longer need to and if you think about the 1983 push sorry about the color the 1983 push in which humorous and laid some line at the end of the cave you know the French had been the Australians have gone a little way and then the French came over and snuck into our cave and and went a bit further and so no we cannot stand for that so these guys went back the next year and took as many cylinders as they could find and one of those tanks are proud to say was my seventy two litre aluminium tank that I bought soon after my course so they they took all these cylinders out there and tied them all together and drag them through the cave and use these big sleds with built-in buoyancy control and over a period of time they use this equipment and this many divers four sleds and spent 55 hours underground to add something the cave they're underwater times 11 hours and they reached six just over six kilometers now compare that with the streamlined efficiency and attractive nature of those two drivers who essentially repeated the same dive a few years ago without that without the need for that massive infrastructure of course when Craig and I went back to try and add a bit of lines at the end of humorous and so actually to Chris Brown's line you know all the hard work has been done the lines been laid for us in front of us but regardless we we could go out there with three rebreathers between us for small scooters with lithium batteries and about eight open circuit cylinders in the cave underwater at time about nine and a half hours and underground time only 19 hours and about 120 meters of line laid by Craig at the end of the cave so yes you can still do it on open circuit and there there a divers still going out there and camping in the second air chamber and and doing all this on open circuit but it seems that rebreathers have perhaps change that unfortunately there is a price to pay for technology and whilst we're developing our own lithium-ion batteries for our scooters to do these dives we've found that they're also very combustible and if you put them on the roof rack of the car and they rub together on the way home then the result is a burnt-out Nissan Patrol to the left of the screen on the floor that that sort of white and black smudges of mark 15-5 rebreather that I used to own and there's also some nice camera equipment in small aluminium puddles on the floor there but Ken Smith in the background who many of you know a regular visit of the Florida Florida caves he he said thank God I didn't have any insurance because all that paperwork's a real pain so just before I did that cockle Biddy expedition I was lucky enough to be invited by a guy called Paul Hosey who is a very enthusiastic Australian cave Explorer to visit a cave that they're just found in the Kimberley's which is in the very northwest of the whole country and it's a truly remote place there's no way to get to this site by by road or even by foot the only way in is from a small aboriginal settlement called warn them by helicopter helicopters are there because they take tourists to fly around the bungle bungles which is that sort of beehive range as you may have heard of so this this site called kid you blue kid jizz the name of the local Aboriginal people is in the middle of the Kimberley's and basically had been dived others the map so it had been dived by one guy who lived up there he took a single tank in there he saw this from his own plane I think and then hide a helicopter went in there did it just a single tank air dive in the lake and thought it was so beautiful and so special that he swore he would never tell anyone about it well fortunately his niece was a local caver and over a period of about three years she can't have got the information out of out of him that there was a cave there and Paul went back and hired a plane and sort of mowed the lawn with this plane back and forth for about three days and took about the last ten minutes of the last flight he actually spotted the thing and wrecked it in the GPS so this place has reached only by helicopters now as I mentioned as soon as you turn on the motor for a helicopter you start paying and you get your wallet out and that's a very unpleasant business so this was the first time we've done any helicopter diving and we were so frightened about how much it was going to cost that we decided to take the absolute bare necessities including you know horrible freeze-dried food and you know no water and assumed we could drink the water and all this sort of stuff that's a picture of the helicopter with a couple of big oxygen cylinder strapped to the side Vietnam style and that we camped there for about 11 days you know doing it pretty rough but the most spectacular place and there's this no way we could have taken enough equipment and some wonders in here to dive this this cave was open circuit and as it turned out the cave then out to be magnificent and that's a shot from me hanging on the abseil rope into the entrance of the cave looking down into this big present shaped lake which is about 350 foot long like your own private lap pool and truly glorious glorious place to visit lots of chambers within chambers underneath the thing and quite a complex three-dimensional structure but basically flowing down the hill this thing is a perched water table and it fills up in the wet season and then during the dry season that slowly leeches out the bottom down to a spring further down the hill which you can see where the arrow that says approximate extent of deep cave passage just near there there's a little wet soak where the water slowly comes out over the course of the dry season it's a very beautiful spot and the first experience we had with this sort of helicopter diving now once you've done a helicopter cave diving it there's no going back he's completely addicted so into the Pierce resurgence their next helicopter diving project now the Pierce resurgence is a cave that I'm very angled up with I guess emotionally and certainly financially now after having started going there in 2007 with another well-known Australian cave diver called David appley who did a huge amount of exploration in this cave and I was lucky that he invited me tour I actually I bought it myself to go with him but that doesn't matter and so I went there in 2007 now the Pearce resurgence is in an area known as the Mount Arthur ranges in the South Island near Ernest Rutherford's house in Nelson and it's very famous for its very tall vertical caves probably not tall by Bill stone standards but certainly tall for the southern hemisphere and there are caves that are up to a thousand meters now in vertical height and just around the corner from one of these caves called metal bed cave is the Pearce resurgence and the hole places is metamorphosed limestone that is marble and freshwater Clues II and spring which means that come Wells up from deep underground and it sits at about 300 meters elevation and the only way to get in there is with a helicopter so once again we're looking at deep diving with open circuit perhaps which would mean a lot of gas and it has been done in fact David Dooley and Chris Brown didn't an amazing expedition there for us and explored they've down to over a hundred and twenty meters I think on open-circuit but I think David would agree that would you know the amount of time spent mixing gas and the amount of gas they would have had to take him was a little bit prohibit prohibitive and certainly once we started to push past that 125 meter depth then I just don't think we could contemplate it on open-circuit the other big problem of this cave is not only was it becoming very deep but it's also very cold about 43 degrees Fahrenheit six six or so degrees Celsius and that's in the middle of summer it probably doesn't get any colder and we try don't know but it certainly covered in snow everywhere else outside the cave so we're not going there in winter for the depth as of last January when we've just been there again it's actually 221 meters not 212 which I would suggest would be the deepest cold water cave in the world at this stage and the problems of diving deep in a cold water site like this a pretty self-explanatory particularly with issues concerning co2 and scrubber durations and all these sorts of problems top of the map snipped off I'm sorry but it's virtually at the surface there you dive into the entrance and down this shaft the main shaft they had down to about 105 meters and then you turn right on that map and go past what's known as the big room continues down the black line there to where you can see Rick Stanton's name Rick was also on this trip in 2007 with Dave happily and myself and Rick did this amazing dive on his homemade side mount rebreather down to 177 metres and tied off his line and only actually stopped at that point because the primary light which belonged to me imploded and he had to turn around and come out I went back the next year and pushed down just a very short distance down to the next level there at 182 metres and then with Craig Challen and some other guys who have become collectively known as the wet mules which is a little team they we've been going back to the cave and and really trying to overcome that the issue Merilee of thermal protection in this site as the dive times have started to stretch out from three to four to five to seven to ten to twelve hours and six degree water and each year we've gone there we've learned more and more about how to look after a thermal protection and pollux talk this morning was obviously of great interest to me and I can't wait for this aerogel stuff to appear and put on the whole suit of it but as I say I think this would be an impossible quest now on open circuit to be considering these sorts of depths as I mentioned there's obviously enormous gas savings for long and deep dives that reduces our expenses from the helicopter point of view the warming and humidifying effects on the rebreather there are enormous when you for any reason go off the rebreather onto open circuit you feel the difference very rapidly indeed it's quite unpleasant the constant po2 makes this much easier to do decompression calculations particularly we're not quite sure exactly what depth or time you're going to end up with and obviously the decompression is much more efficient without those spikes that Simon showed on his graph this morning and my mind I'm actually not I wouldn't call myself a rebreather advocate I actually prefer diving on open circuit sidemount open circuit cave divers my favorite kind of diving and I'm I am a little fearful and certainly very suspicious of rebreathers which is probably a good thing but I'll tell you when you're at depth or when you're in the overhead environment is extremely comforting having a rebreather knowing that if a problem arises you've got any amount of time to sort of sort it out so for me that's the huge benefit for that technology the thing is just trying to mix gas between dives in this environment even with little three litre rebreather bottles it takes forever so to do it with the open circuit would be unmanageable Simon's mentioned the cost of helium in our part of the world I think Simon you might be paying retail there mate if you're paying $1,000 a bottle because I think it's more like three or four hundred if I see in Nelson but but certainly the retail price is over nine hundred dollars a cylinder so without going into the details here to do the open circuit dive to 185 meters that we did one year nearly one and a half thousand dollars just for the helium for a single dive on open circuit the helium for the rebreather dive about $70 and doesn't include the savings on the helicopter which are another few thousand if we had to take all the extra guessing so there's no doubt that once you've paid off the loan on the rebreather there it starts to put you in front now just tell me a little bit about the logistics of how we're doing the dives in this site in the top forty meters of the cave we've installed or we each time we reinstall four habitats which are just the one cubic meter what what transport containers we call them intermediate bulk containers they use for detergents and pesticides and stuff like that so give them a good clean-out turn them upside down in the cave and bolt them and rope tie them with ropes to put them in the cave so we've got four of them one at forty meters one at 28 one at sixteen and one that seven meters part of those depths is just the logistics of where they fit in the cave part is some decompression planning in mind we're now using rebreathers in pretty much each of those habitats so after the push dive we come back to the first habitat at 40 meters take off our main unit into the what do you mean a habitat and put on a or rest on their lap a strip down kiss rebreather so the cylinders are taken off there's no wing nor harness on it and we just rest it on our lap put the loop on and the cylinders are on long hoses hung underneath the habitat when it's time to move up to the next habitat we go back in the water clip the rebreather off to a harness that we put on and then clip off the two cylinders and with a support diver at all times that's a really important thing to emphasize with any sort of habitat maneuvers and up to the next habitat and so on up to the 16 meter habitat where we've now using what we call the wet meals man-bag CCR but it's actually a ripoff of the thing called the next generation rebreather which many of you will have read about on rebreather world I'm sorry okay the inventor of that but it's basically a beautiful little simple rebreather made from a gas mask bag and so we've adopted a couple of those for closed-circuit rebreather for the deeper habitats and an oxygen rebreather for the shallow habitat now this is a very exciting video that I'll reenact now of the habitats and swimming down see the habitats with all the paraphernalia hanging below them we've got surface supplied heating cables going down as far as 50 meters and you can take those cables up with you all the way through their habitats and we have radios in the top two habitats to talk to the surface and we also have a buzzer box that Ken Smith invented for us that goes all the way down to 110 meters and at every 20 or 30 meters you can press the buzzer and all that the surface of the fact that you know you're on your way up it's particularly good for the surface to know when that first hundred and ten meter buzzer goes off then we can start to quickly you know make a decompression calculation we know roughly where the push divert is and when we can expect him up at the 40 meter habitat roughly so that start to work really well for us all these push dives are done solely and for the main reason that we feel that there's absolutely no way you can assist a second diver in distress at those deaths so feel as much safer actually by by yourself it's all relative I guess so that's the oxygen rebreather and as I say many of you will recognize that it's not our design but works beautifully well and we just clipped that to the hook on the roof of the habitat and the loop just sits nicely in your mouth and it's very light and comfortable and I heard Martin Robson talking about habitats that sitting in a habitat and breathing open-circuit is dreadful because of the noise and the vibrations it's really unpleasant sitting on your rebreather you can be very comfortable and that's the main bag from 16 meters which is got a sheer water HUD on it and we use that as the primary end and only po2 display which is heresy I guess but it's very important that this is light and compact and this sits in your mouth with no fatigue and I'm convinced that the decompression advantages of being warm and dry in a habitat are enormous and in fact in a suit a tiny series I guess of about 15 or 16 dives between Craig and myself over a hundred and sorry and dave and Sandy over 150 meters not even had any nickels which is certainly a lot better than her track record in the hundred two hundred and twenty meter range now the last thing I want to talk about a little bit is to spend a bit of time talking about planning bail out for these kind of dives which is real issue obviously and Craig and I spend hours and hours and hours going back and forth the pros and cons of all the different possibilities for doing deep bailout and it's worth this community just thinking a little bit about the options and president cons we all accept that we need bailout and particularly for all diets full stop even the the little duration of open-circuit depth the idea of a second or bailout rebreather is very attractive one and Craig has addressed this issue by twinning up his Megalodon rebreather and acts to Jacob from Gollum Gary's now that a twin off as well so flicker the switch and they can go back and forth between one loop and the other loop it's a huge device I'll show you some photos in a minute but once he's got it on it's pretty comfortable and works very well for him guaranty a secondary breather if there's a problem with the first you don't have to change your decompression planning you know you can pretty much carry on as as normal that's a photograph of his dual pilot valve which again looks complex and frightening but it's actually a very simple device and beautifully designed now the problem with bailout rebreathers is that firstly they need to work when they're required they can't be flooded and they have to have a breathable gas inside them so that means that on the descent and during the dive you have to do some kind of have a system to check you or a second rebreather throughout the throughout the dive now that adds enormous complexity and task loading to an already stressful and difficult situation so for those reasons I've been a little bit nervous about embracing that technology and I think having to rebreathers in a compact form on your back like craig is is probably a way to go if you're going to go down that path certainly need to have dive that configuration many many times would be very comfortable where everything is before you contemplate doing any sort of deep diving in fact in this sort of environment when you're in dry gloves and you're wearing very bulky and heavy undergarments your mobility is very restricted any tiny change to your gear configuration needs to be rehearsed and practice in shallow water before you take it anywhere else it's amazing how the tiniest changes one little or hose routing or a minor thing can cause things to become a little unstuck when you suddenly realize you can't reach it or you don't know where it is or it's had some other implication I've made this little matrix for the way Oh basically I've this is about trying to win the argument with Craig basically and why I believe that open-circuit bailout is a better option for these dives and I approach the concept is this that I look at the likely possibilities of problems with the rebreather and whether they would make me require to bailout off the primary rebreather and then secondly whether if I did bailout off the primary rebreather whether the rebreather would actually do what it needs to do that is giving me a breathable gas in a way that I can return to the surface safely so looking at the common reasons why people might think about bailing out if the primary loop floods first of all I consider that to be a rare event you know it's an unlikely thing although yes it does happen from time to time do you have to bail out if you flood your loop well yes I think you definitely do and if you've got a bailout rebreather we're bailing out onto it in that scenario be successful maneuver well if the rebreather is working fine then yes the second rebreather should be optional for bailout the second problem is problem problems with the electronics again with reliable electronics that we now have the chances of a problem arising underwater I've certainly had plenty of electronics problems before I've jumped in the water which have made me have to abandon the dive but once you're under way it seems pretty rare the electronics problems arise but if they do do you have to bail out well it depends on the problem I guess but usually you have some other options like go into a semi closed mode or another way of managing the problem but if you decided that you're unhappy and you wanted to bail out well the bailout rebreather if it's working well should solve that dilemma for you if there's a problem with the guest supply of any kind if the oxygen fails or runs out or there's a problem with solenoids sticking open and it spikes again there are other options you can approach that problem with and you may not need to bail out but if you do the rebreather the other rebreather should be working now when we start to look at co2 problems it's become little less clear to me what what the answer is if you had a problem with the scrubber for example a packing problem some breakthrough or you had exhausted the scrubber material and you developed a co2 problem first of all it the likelihood of that sort of thing happening in this cold water prolonged diving scenario is more than low I think in fact we've had one or two minor co2 incidents along this these lines is the is bailing out mandatory well yes I feel it is mandatory to get off the loop and if that happened would the second rebreather solve the problem that you you're experiencing well Craig is adamant that if he detects it early enough then yes the second loop will fix that problem I'm slightly less convinced that even early detection of you know co2 because you've sensed it yourself going on to a second rebreather may still be causing you some arrests I think that open circuit is a better option now maybe that's just for a short period of time and then you can safely go on to the second loop and that's a reasonable approach so foot may be there for that one because you can probably argue both ways the big worry that we've all got about this diving and anyone who's been fortunate enough to hear Simon talk about the analysis of David Shores accident and this concept of independent respiratory insufficiency will be aware that the deeper you go the more likely this problem is that you yourself cannot clear co2 from your body because of respiratory issues and should that arise a yes bailing out off the loop is mandatory but going on to a second rebreather I feel and I think most people would agree will definitely not solve the issue you just changed you changing the equipment but the problem still resides within the diver so I think that the only hope for resurrecting that problem should you become you know a long way into that vicious cycle of difficulty breathing is that you need to get onto open circuit and hope that that will break that cycle and ascend from depth to decrease the gas density which will also improve things and then if things have settled down yes you can go back onto the loop so I looked at this and I thought well the biggest thing I'm frightened of in these deep cave is this problem of respiratory insufficiency and I won't going to all the physiological details of that obviously now but that was my greatest fear and yet the bailout plan that we're talking about it was a system that is not going to help in that in that particular scenario so I felt that I needed to stick with open-circuit bailout this is the other video is going to show you some nice video of me laying line at 200 meters which is would have been nice but the things in this video that I wanted to show you were a couple of problems firstly nificant HP NS was shaking hands and difficulty doing simple things like tying off this real deployment knife to cut the line and the audio actually to my anesthesiologists ear tells me that there's a little bit of the first hint of this effort induced respiratory failure sorry effort independent respiratory failure that is you can hear a pattern of respiration which is starting to head down that path it's very very subtle and very early but you can certainly heard you can certainly hear very loud banging closed of the flapper valves in the mouthpiece which you don't hear at shallower depths from the gas density and you can also hear the occasional prolonged expiration and little grunt at the start of each expiration so you hear this sort of sort of noise which is just the start of this pattern that Simon's described so well anyway that's for another day I'm sorry but it is you know I'm happy to share that round for those who are interested so just to finish up with a few pictures of breathers that we're using so that's a picture of Craig's Megalodon from the back on the front as you can see it's a complex looking beast and you know to help him dress into it I just look at it go where is all the bits you need but you know he's spent an enormous amount of time on this unit and it's very very comfortable on a DIN deep now and it works very well for him now two of our other divers sandy baron and dave body are both rivo divers and they've approached the problem in a slightly unique way by putting an r2d2 on the side of the unit that's an inspiration taken out of its box and and clamped to the side with the second loop around with two separate loops with not a common bailout valve and they've successfully dive that 200 meters and again seems to work very well for them now of course I have to defend my position of planning on doing open circuit bailout at 200 metres which is not an easy problem to do and I'm not suggesting for a moment I've got it right but if you do the math on this it's not very attractive at all in fact if we look at an 1111 litre cylinder which we pump up to 250 bar for these dives about 240 cylinders and if we assume as someone said earlier when you're having a crisis and you'll actually planning to bail out I normally plan for a swimming sack rate of say 20 liters per minute I'm very confident it would be at least 40 liters per minute for a short period of time that's all hitting the fan so if you're breathing 40 litres per minute at 21 atmospheres it works out to roughly 3 minutes per cylinder with a bit left over that you can't get out of the tank because you're too deep so I'm carrying 3 sometimes 4 cylinders for these dives and the first ones plugged into the bailout valve so at least I've got that one for 3 minutes that that's assuming the bailout rig works of that death switch I'm not gonna test just for experiments sake gives me about 10 minutes to get back to the 150 meter stage tank which on the scooter takes about 3 minutes if you just go for it though I'm not pretending there's any margin of safety there whatsoever but I do believe that it will give me an option in case of this respiratory insufficiency problem we've tried staging rebreathers in the cave and we should have listened to Rick Stanton's advice to him that he was correctly saying that so they always flood if you sit there and leave them switched off they just gradually flood and some you know cave divers have recently found that out to their cost my unit is just a straightforward Revo basically with the 220 amp hour like battery packs on the sides which I plug into two bulkheads in my suit from my painting garments and and an argon cylinder on the on the side which we are still persisting with despite minimal evidence for it efficacy but I figure plus SIBO is as good as any effective here bloody cold so we'll stick with that for a bit side-mounted kiss which friend of mine and I've have put together was my original bailout plan but as I say it I've gone away from that idea so I'm just gonna finish up by just talking a little bit about you know the future of rebreathers for this kind of diving there's no doubt that rebreathers are going to become more efficient or reliable better self checks automatic bailout systems have been proposed co2 monitoring is obviously it hot at the moment proof reliability and in oxygen sensors and maybe even some small improvements in work of breathing will be possible but let's say we can build a rebreather that is completely diver proof of course none of that will help with this problem of deep diving gas density and respiratory issues we face so my feeling is we've probably reached or even actually passed considerably the safe limit of depth for rebreather diving the I think this is a US Navy study that was a feasibility study into a 2,000 foot rebreather she was published way back in the 70s and a fan-forced component to actually push gas through the rebreather to him to decrease the work of breathing I was proposed and that's the only thing that I can think of that might improve this situation a little bit but this sexual unit is a surface supplied apparatus I think feeding into the you know the rebreather stole helmet and you know very complex and drive that motor for a period of time would require battery packs that we probably haven't got available but if any of the manufacturers are interested in building something who live like that for us we might be able to put it to some use I'm glad that Leon actually mentioned this in his Reiser talk because I've been slowly working my rope way around the room harassing the manufacturers and also talking to you know emailing people in the past about this but as someone who's involved accident of fertility investigation as part of my interest in my work it's have some concerns about if a rebreather diver dies in South Australia where I'm from the first thing is that the South Australian police water recovery unit are gonna get this rebreather and they know nothing about rebreathers whatsoever so they're going to call someone like myself who has some experience with rebreathers to help them analyze the unit now if it's one of the couple of rebreathers I'm familiar with I may be able to do a half reasonable job at that but if it's one of the myriad units that I don't know anything about then there's a fair chance I'm gonna make a mess of it and no Martin Parker has published an extremely detailed step-by-step paper on how to analyze a rebreather after an accident or a fatality and in submarine trip that Andrew Falk and I were on in in Turkey where there was a near-fatal accident we used that paper to analyse the equipment and it was enormous ly helpful so my request would be to reinforce what the research group is is asking for is to preferably put it in the public domain so that it's widely accessible for all the manufacturers to make a step by step analytical form so that people out in the field can approach different units you know in a sensible and comprehensive way without missing vital information that obviously benefits the rebreather community to work out what's gone wrong and obviously benefits the manufacturers to avoid any false accusations of an equipment problem we're most likely it's a diver error or if there is a fault with the equipment then that becomes more widely known so that would be my one safety message for my talk and I think that is the end thank you very much for your patience

Channel: DAN TV

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Id: YJFF6t0ohuc

Length: 45min 43sec (2743 seconds)

Published: Tue Mar 19 2013