Rebreathers Open Inspiration Fully Closed Rebreather What Is It Like? Text & Photos by Peter Symes Diving Rebreathers Why Bother?

WWW.AQUALUNG.COM Dräger Ray semiclosed rebreather. Behind, an Rebreathers open Inspiration fully closed rebreather What is it like? WWW.AMBIENTPRESSUREDIVING.COM Text & photos by Peter Symes Diving Rebreathers Why bother?

Rebreathers look cool, glitzy, tech- they provide for a much differ- nical and heralded as the future of ent and richer diving experience, which, in the first place, is why we go in diving, right? We read a lot about the water ourselves rather than watch- their impressive performances con- ing dive movies on Animal Planet from cerning duration of dives, gas econ- the comfort of our reclining chair at home. omy, extended no deco limits and However, as we all know, there is no such thing as a free lunch in diving either. There is what not. But isn’t it a bit like watch- a trade-off, and you will have to consider if it the underwater realm so you can have an ing Jeremy Clarkson from BBC’s car is still worth your while despite this. enriching experience by witnessing, first program, Top Gear, whiz around in It is not merely a matter of comparing hand, this magic realm. So, as far as I am fancy Ferraris and Aston Martins with technical matters, performance and param- concerned, if someone invented human eters when pitting rebreathers against the gills and a thin hide to cover and keep me a goofy, happy grin on his face and open circuits (regulators and tanks). It is warm, my twin-set would surely be left to rust reeling off a string of excited super- easy to be blinded by dazzling numbers and in the attic for good. latives? Yes, they look fabulous and facts on how much longer you can stay I just want to see fish and other underwa- under water with no deco-obligation and so ter life. I want to get as close as possible sound fabulous, but you’re still not on, but consideration should also be given without disturbing the sure what all the fuss is all about and to the sensation and experience of diving creatures, and for what’s in it for you... and whether you rebreathers. me, this is could actually afford one. I think these subjective matters have been exactly grossly overlooked in textbooks and articles. Rebreathers aren’t exactly an impulse buy, Yet, how can we put words to them? but they don’t quite require the same deep pockets as a super car. So, you could actu- Why? ally own one if you put your mind and piggy Wine connoisseurs have a whole weird bank pennies into it. vocabulary to describe all the flavours They do come with the same sort of built- of wines, but describing diving the in bragging rights and can still gather a rebreather experience to an open crowd on a beach. However, the glitz fac- circuit diver still feels somewhat tor shouldn’t be the only reason for getting like trying to describe a sunset one—there are easier routes to impressing to a blind person: “It’s... erh... members of the opposite sex. just really cool and... uhm...” Any piece of equipment is Diving experience just a means to an end and The reason to go with a rebreather should not the end itself. It is a means be their performance in the water, and that of transporting you down into

Aaah! Silence at last—and the Unbearable Lightness of Being starts to sink in Black goby, Baltic sea 65 X-RAY MAG : 6 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED Up close and personal. This squirrelfish Rebreathers tips almost sat on my mask

what all the fuss and hype Comparison Rebreather-friendly is about with Let’s go on a dive and compare how dive centres & locations these gizmos. open and closed circuits perform. In Do check the list of so-called rebreath- I am a pho- the following, I will use a fully closed er-friendly dive centres before you go. tographer, so system for comparison rather than the It could save you quite some hassle aside from more widespread and more economi- and money. You can find these dive the better cally accessible semi-closed system centres on various lists, ie. online bulle- personal since the fully closed systems are the tin boards and web sites. For example, experience, I thoroughbred of rebreathers, and you could use this one at the Ambient can also get because I am better acquainted with Pressure web site: www.ambientpres- better pic- this type of system. surediving.com/ccrdbint.htm) tures when I Before we even get to the water, So far, it seems that open circuit sys- don’t blow or there is the matter of transportation. tems lead closed circuit systems 4-0 in scare all the If you are going to the beach in your the why-bother score due to the hassle and remains stretched like a drum-skin. critters away. own van, there is not much difference factor. If not, we have to go over all the seals For me, the in hassle when it comes to transporting and joints once more. longer no-deco a scuba set with tanks and regulators Before the dive The open system now leads the score times that these or a rebreather. OK, we are now at the waterfront with 5-0. units give me But if you have to travel by air, we all our gear spread out, rigging up. Mr. Next, comes the fire-up sequence are great but not are talking about a completely differ- Open Circuit mounts his BCD on a tank, where the rebreather diver stares very a prime concern. ent ball game. Going by plane, the regulator on top, opens the air and he intently upon the unit’s handsets (the Although, I have on open circuit diver can bring along his is ready to dive in a minute or so, save controllers). Do not distract her at this more than one occasion, or her regulator and BCD, or the diver the odd popping o-ring experience. No time! appreciated the fact that I can opt to hire everything at the desti- complications here. The electronics on the handset are could just stay down there at nation. The diver doesn’t have to worry Ms. Re Breather, on the other hand, taking the diver through a “pre-flight” depth to get my shot far long- about carrying tanks either, so there is has a lot more equipment assembly sequence of actions and tests, and she er than an open system would not too much excess baggage. to do, some testing on top of this, and must respond to these accurately and have permitted me. Rebreathers are different story. then some “pre-flight procedures” to observe closely that the rebreather Other CCR divers may have other undertake. responds correctly. By pre-breathing uses and other subjective reasons for The check-in challenge After assembling the unit, we first the unit, the diver makes sure that it liking their units. For instance, rebreath- It isn’t quite the same for the poor have to do a negative pressure test, operates properly before entering the ers have also become quite popular rebreather diver who might have to where we, under eye-popping strain, water. among some wreck enthusiasts, techni- schlep quite a bit more hardware onto suck all the air out of the unit, close During the start-up sequence, the cal divers and cave divers. the plane. It is not an issue to be taken the mouthpiece and watch it to breathing loop is filled lightly these days when airlines are less see whether the counter- with 100% oxygen Hearing and less tolerant of passengers who do lungs remain deflated and to calibrate Another major reason why I have not head weight limits and bring along squashed like vacuum- the sensors, a richer diving experience on my overweight bags. packed coffee. so we rebreather is that I can hear better—no The rebreather diver must rely on the After that, we then have to noisy breathing apparatus or bubbles— destination dive centre to fill his or her do a positive pres- and so, can more keenly sense what oxygen tank, and if the diver is lucky, sure test where is going on around me, even when I the dive centre can also supply CO2- we inflate the unit do see it directly. I have a much more scrubber and rental tanks. If not, well… fully and make it acute sense of the three dimensional let’s hope that overweight charges look like an over- space around me and what is in it. But aren’t an issue for you. blown tire to see let me get back to that later. if it holds pressure

On a rebreather, I often get the sense that I can hear what is going on behind me 66 X-RAY MAG : 6 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED A couple of worthwhile tips Rebreathers rebreather resources: www.therebreathersite.nl www.rebreatherworld.com Weight can As you descend, the increasing ambi- become a real issue ent water pressure also starts to squash Some manufacturers: when travelling with your counterlungs flat. They have about www.steammachines.com your rebreather. the same volume as a BCD, but need www.customrebreathers.com If possible, sort it a constant volume in order for you to M www.ambientpressurediving.com ot beforehand. have something to inhale. www.ccrb.co.uk Sometimes you can negociate a fair Unless you add some more air (or price on overweight diluent, which can also be some other (Above list is not exhaustive) before you go - or breathable gas) on your way down— buy some extra either by manual injection where you allowance. do a series of small bursts, not unlike

what you do with your drysuit, or by the WWW.CUSTOMREBREATHERS.CO means of an ADV (Automatic Diluent observe that the oxygen partial pressure a little water into our masks, and then Valve)—you will soon enough find your- drops down from 1 bar to stabilise at clear it by an exhalation through the self sucking very hard for no air... not so 0.70 bar partial pressure, which we have nose. On open systems, this is just some- comfortable, so you only do that once. chosen as our low set point. thing you do, and many divers exhale Some 5-6 meters down, or if you are This is the oxygen level with which through their nose on a regular basis. at the bottom of a somewhat shallow we start the dive. Any wrong or erratic On a rebreather, this is a big no-no, as it coral reef, you pause and look up for behaviour of the oxygen sensors will means venting precious gas out into the the tell-tale streams of bubbles that The Megalodon is another popular show in the readings or produce an out- environment. might indicate a leak. You can also ask CCR-rebreather on the US market right error-message, of which you must On rebreathers, you clear masks very your buddy to look around for you. strive to find the cause and correct carefully and sometimes in a cross-eyed If everything’s fine, you may proceed before you can dive. manner as you try to watch exactly how and switch to the higher set point, Finally, we can hit the water. Upon much air is required to just push that last where your oxygen level is kept at entry, or slightly into the descent, it may drop of water out of the mask without 1.3 bar partial pressure. Only below 3 Prism CCR from Steam Machines as it was pre- be our habit to clean our masks. We let losing any air. meters at which time the ambient pres- STEFAN BESIER, WITH PERMISSION FROM STEAM MACHINES sented at DEMA 2003

The ADV (Automatic Diluent Valve) on a Inspiration CCR, makes sure that more air gets automati- cally added into the breathing loop upon descent

Hovering becomes a delicate skill when diving rebreathers. You need to be far more accurate in regards to how much air you have in your wing or dysuit. But once you get it right, you will lie com- pletely still—even while breathing in and out

67 X-RAY MAG : 6 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED tips Mouthpiece Rebreathers sure is at least 1.3 bar, can the system level given much mention in various Flow-diagram and the whole breathing loop with air from maintain a 1.3 bar partial pressure of text books. This feature allows you, all of main components Air/ diluent tank my air (diluent) tank. With one hand, I oxygen, hence, the need for a lower set sudden, to hear or sense what goes on of a Prism Topaz keep pressing the inflator button down point at the surface. (On newer rebreath- behind you. It provides you with a 360º CCR-regulator. The injecting air, while I pull the cord to keep ers, like the Evolution, this set point switch- awareness that is not so unlike what you diver’s lungs and open the over-pressure valve that is vent- the CCR’s counter- ing can be set on automatic.) have on land. On land, you can usually ing air. I do this for say, 10-15 seconds, lungs, scrubber and It is, after all, this bother that permits hear when somebody enters an area hoses has a con- after which the entire atmosphere in the the rebreather to flourish and deliver its you occupy even if you are reading a stant total volume Scrubber breathing loop should be exchanged promises. This is where it picks up on all book and facing another direction. with air, which I know I can always the points leading to an enhanced div- breathe. Needless to say, this procedure ing experience. Buoyancy issues Counterlung is quite wasteful of your relatively small First of all, there is this amazing tran- Continuing on our journey, we swim, gas supplies. quillity—you can’t hear a sound except, down a slope. As I sink, I compensate for If I am still in doubt for some reason, maybe, noises from your buddy’s equip- lost buoyancy with squirts of air into my the golden rule is to “bail out”. That ment. And this is what I treasure most on wing, and then, to halt my descent com- means switching to open systems, which the rebreather: you regain the practical pletely, I take the traditional deep inhala- Oxygen is either a regulator connected to the use and sense of hearing. You are not tion, which would, if I were on an open tank rebreather’s air (diluent) tank, or a com- cocooned any more in cascades of bub- circuit, have halted me just above the WWW.STEAMMACHINES.COM pletely separate system, ie. stage tanks. bles and heaving, wheezing, whining bottom. Not so on a rebreather. If I switch, it is paramount that I remem- valves. This time, I most ignominiously plough no effect on overall volume and buoy- I can still just hang around to make the ber to close the mouthpiece, otherwise You’d be amazed how much noise straight into the muddy bottom flat on ancy. most of my roll of film. water will enter the breathing loop and open circuits actually make, but it is hard my face. The reason? My lungs and the Boy, does it make you feel stupid when But unlike my open system buddy, I do replace the air resulting in a very consid- to fully appreciate this before you try and counterlungs on the rebreather main- you bite the dust this way. have to watch my handsets, my con- erable loss of buoyancy. experience the alternative yourself. tain a constant total volume, so when I Buoyancy on a rebreather is a more trollers, at regular intervals to make So, what should you know and be I haven’t seen this change of noise inhale, I just empty the counterlungs with delicate thing. Because you can’t use sure that I am still getting the right able to do? What should your buddy, your lungs to fine tune your hovering, nor Nitrox blends. On a closed circuit on an open system, be able to do to “Artist’s impression” of the 360º awareness sensation will your breathing disturb your position, rebreather, I always have to know assist you in case you run into trouble? you won’t bob up and down with each which gas mix I am breathing and A CCR rebreather diver can become breathing cycle, which is really great that it can sustain life at a given depth. unwell for all the same reasons that an once you have nailed it and want to lie On open systems, once you have open circuit diver can, plus a couple completely still with a pygmy seahorse in the regulator in your mouth, you more things can happen including the cross hairs of your camera viewfinder. only have to breathe it and you are hypoxia, hyperoxia and hypercapnia. For the very same reason, a rebreather set. Not necessarily so on a (CCR) (too little oxygen, too much

diver will prefer to swim around an object rebreather, which is a mobile nitrox oxygen and too much CO2). rather than over or under it. Ascending mixing unit. As such—if anything goes means venting gas, which you lose for awry, God forbid—it can serve you a good. gas mix too lean or too rich in oxygen Diluent flush At depth, I have several other advan- for your own good. maneuvre. tages over my open circuit buddy: I Too little oxygen leads to hypoxia, Illustration adapted won’t run out of gas any time soon. and you will faint. Too much, and from Inspiration My on board gas supply will last me you run the gauntlet of oxygen manual (Ambient Pressure Diving) 10-12 hours, although the CO -scrubber toxicity, which brings along with it 2 Simultaneously shouldn’t be used more than 3 hours. uncontrollable cramps. In either pressing the diluent And with lots of non-deco time to go case, drowning is imminent. This feeder and pulling around at medium depths, it also gives is why knowing at any given time the over-pressure me peace of mind and no stress. what you are breathing is one of valve chord al- It is the Zen of diving. Should a school the golden rules of CCR-diving. lows air (diluent) of hammerheads parade by 45 minutes If I am ever in doubt, I may first to replace what- into the dive when my buddy’s open perform a strangely looking exercise ever gas was in circuit system would be down to 40 bar, called a “diluent flush”, where I flush the breathing loop before

68 X-RAY MAG : 6 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED This little Rebreathers green knob is the valve to maintenance and cleaning of the the O2-tank. unit. Rebreathers need to be disinfect- Buddies should ed at regular intervals because the know how to unit has recycled air that has been in The check and open it and out of your lungs numerous times. Semi- closed The verdict? rebreather Dräger It seems that you will have to endure Ray comes—at the If I am in trouble and appear unre- a bit more bother and complexity time of this writing—at a sponsive, it is first of all, important to when diving rebreathers. Which brings suggested retail price of around ensure that I don’t drop the mouth- us back to the main question: Is it US$ 2,000, making it just a little bit piece for the reasons just mentioned worth it? more expensive than a complete and to prevent me from drowning. Yes, it is. Rebreathers are certainly scuba set for open circuit diving, that It could also be beneficial if you know not for everyone. The ease and is, regulator, BCD and tanks. how to perform a diluent flush on my uncomplicated aspects of the open The fully closed rebreathers are system. So, before we enter the water, systems will still make open circuits more expensive and will, as a rough we should perform a little drill. Also a better option for many as well as guide, come in the US$ 5,000-10,000 you should know how to open my O2 a certainly more economical and range for the most popular consumer valve, in case it has become closed accessible one, ie. when you bring models. This is, admittedly, not exactly and caused my problem. Other than your family along on a trip. pocket change for the average blue that, all the usual drills and techniques But for those who are willing to go collar worker, but not totally out of taught at any advanced or rescue those extra nine yards to fully appreci- reach either, if you really want one. diver course applies. ate what it is like being down there It all comes down to a matter of On the ascent, the rebreather diver soundless, bubble-free, the way priorities. Do you want to have the will once again become more busy. nature intended, the rebreather is kitchen refurbished, or one of these As the breathing loop contains a sub- the thing that will get you hooked for great machines? Well, that is a matter stantial amount of gas, this also has to good. (Don’t say I didn’t warn you) for you and your partner to sort out. be vented in a controlled way along I have already mentioned the Safe diving! ■ with that of the wing or drysuit in order soothing silence, but the ability to be to perform a controlled ascent and to in the water and have a sense that The Ourosboro rebreather by Kevin Gurr do the required safety or decompres- you are truly part of the environment is one of the newest CCRs on the market. sion stops. rather than being the noisy intruder, is See the New Equipment section for more Before I go shallower than 3 the priceless part. The wildlife acts dif- information meters, I also have to ensure that the ferently—your presence is somewhat rebreather switches back to low set accepted. I wouldn’t go so far as to point, so it will not over-inflate and say that marine life acts indifferently, make me float up like a zeppelin. but the rebreather certainly lets you At the surface, I will not switch to get far closer, and the critter behav- snorkel as some open circuit divers iour seems far more natural and less do, but keep breathing on the unit, apprehensive. mouthpiece in place, until I am safely I have had blennies sitting right on out of the water. This also gives me my mask. This is the closest I have lots of oxygen in the meantime. Also, gotten to feeling like a human fish. It I must not power down the unit while gives you the same sort of Zen expe- I am still breathing from it as the injec- rience as when you freedive, yet it tions and continued replenishment of gives you the time duration of open oxygen is being controlled by the unit. systems and then some. Maintenance & cleaning Footing the bill After the dive, there is also a bit more OK, now we come to the serious ques- to do and hassle when it comes to tion: What is this going to cost me?

69 X-RAY MAG : 6 : 2005 EDITORIAL FEATURES TRAVEL NEWS EQUIPMENT BOOKS SCIENCE & ECOLOGY EDUCATION PROFILES PORTFOLIO CLASSIFIED