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Thread: Is a rebreather for me

  1. #11
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    Re: Is a rebreather for me

    Quote Originally Posted by chaetodon  View Original Post
    Hi to all rebreather divers, I have some questions asking for some advice from the more experienced rebreather divers. To fill you in first, I am a professional diver who lives in Australia, I collect and study marine fish. I have been diving for about 45 years on SSBA and sometimes OC scuba (this gives away my age). I have been doing long stints on air at relatively shallow depths compared to rebreather divers. 60-80 feet generally, sometimes 90 feet. Depending on the dive I do a stop and then finish on O2 at 10 feet, if itís a long dive I do 25 minutes O2 back on air for 5-10 then O2 again. Recently I have been using nitrox which I should have started using years ago. This has been a great benefit to me especially for the depths I work at. My question is relevant to a statement I see posted often. ďIs a rebreather for meĒ
    The two benefits it will give me are enormous. That is, no bubbles so I can get closer to the fish, and secondly, maximum allowable dive time. The negatives however may outweigh the benefits, so begs my question. I have read quite a bit so far and see that good or new gear goes a long way and more importantly a thorough understanding of whatís going on, monitoring my PPO2 regularly and CO2 throughout the dive. I understand the dangers of CNS O2 toxicity and also the added dangers associated with rebreathers, hypoxia and CO2 build up. The basic theory of rebreathing I see is simple, yet I realise I do need to study and understand more the chemical reaction process of the scrubber materials, O2 sensors, calibrations, understanding O2 and diluent feed valves etc etc etc. This and becoming familiar with every component of the particular unit I decide to buy. I imagine itís a must to do a rebreather course or at least learn with someone that has a lot of experience?

    One problem would be for me is I donít want to be geared up like Neil Armstrong. I appreciate tech divers (cave and deep divers) need to have everything available to them because there is no way out! Divers have to rely on their gear, have enough bailout gas and buddy. It is a little different for me as I can bail out easy from the shallower depths. Finally, I am happy and diligent enough to put the time in to check that the gear is set up properly and do my pre-dive checklist. However, I hope that during the dive I can rely on a regular ritual of looking at my PO analysers without having to do much else? How frequently do I need to do this? I understand there are warning alarms on the shearwater controllers. Are these the controllers the best investment to suit my diving (More electronics some say is more to go wrong) If I see there is a problem (which I hope is not too frequent with a good rebreather) I can easily bailout. I was thinking of a simple setup such as a KISS or similar (I feel I need a streamline non bulky set up, because I have collecting equipment to carry as well), but If there is too much rocket science to worry about during a dive, such as if I have one with less electronics to worry about but find I am dealing with more calculations and manual things to do during my dive, maybe a rebreather is not going to benefit me? There are things which I need to do during my dive, so I canít have my dive revolve around the rebreather. I am hoping simple checks will allow me to get my job done and if there is an alert I can bail out? Forgive my naivety I am still learning about these life support systems. Any input or advice is appreciated.
    Hello, unlike many on here, i got into CCR to get closer to wildlife. I have been rewarded a thousand times over with amazingly close encounters with large animals and seen many things the OC divers on the same dive never did. In PNG, I was stealthy enough to surprise a Queensland Grouper bigger than me, which was behind the funnel of a large wreck. The thing snapped its tail hard enough to spin me around, that's how close I was when we saw each other.

    As for safety, IMHO, that begins with understanding exactly how your unit functions, which should be part of proper training, but your research shows you already are way further to that understanding than I was before training. Good habits before, during and after the dive are the result of a thorough understanding your unit and your physiology.

    As for the type of CCR you choose, I think you are generally on the right track regarding the KISS principle. IMHO, the next question is: What is your expected level of task loading? I ask because the most simple CCR is of course a constant mass flow passive O2 addition system. But if you are doing lots of tasks underwater or may have to contend with strong currents, I would recommend an electronically controlled CCR or ECCR which has solenoid O2 addition to maintain set point. These can be as simple as the Prism 1, which only has an on/off switch and simple potted electronics in the head controlling only O2 addition, a 3 LED HUD display and a passive secondary PO2 needle gage which is driven directly by sensor voltage, to the full Armstrong dual handset, vibrating HUD, full redundant deco computers, helium sensors and CO2 monitoring of some kind. Unfortunately the Prism 1 is no longer made but can be found used for very little. It is by far the most simple ECCR.

    Another simple CCR option is an adjustable flow O2 passive addition CCRs like the Pelagian or the Fathom. I think these are probably almost as easy to fly as the Prism 1 in all but the most heavy task loading and high exertion situations.

    Aside from the bulkiness of some of the more fully automated ECCR's is the added complexity of a total system which must track and validate multiple sub systems, and has additional cables and sensors which can fail or send false alarms, and either end a dive prematurely or prevent you from entering the water. I have seen this happen multiple times.

    As for monitoring habits, any unit with a HUD will give you near effortless monitoring. I can't imagine diving without one. The only other task unique to CCR is spiking the PO2 at the end of the dive at 6M to try and hit 1.6 to make sure the cells are linear and not current limited, which can cause false readings at lower PO2s. I do this every other day if I'm diving multiple days. Again, there are units which do this automatically but again they are much more complicated and thus potentially less reliable for all that extra functionality, IMHO.

  2. #12
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    Re: Is a rebreather for me

    Quote Originally Posted by chaetodon  View Original Post
    Thanks for the feedback guys this sounds good, I looked up HUDís (Thanks Dsix36) which seems simpler and more compact than the larger screen display. A try dive would be nice but a pool dive might not help much, most of the training in Australia is in the south of the country 1,000 miles from me. There is one club here in Brisbane but they charge $2,000 just for the course and then that is for a particular RB, add extras to hire gear boat dive etc. Then a new RB is between $8.5K and $12K Australian dollars which is not much better than $US exchange. (Yes expensive whynot? But could still be worth it for me, itís how I make my living)

    A couple of further questions. There is a minefield of RBís out there and I suppose everyone has their favourites. Can you narrow some down for me?
    I guess I could go with whatever parts and service is available here in Australia, although it wouldnít bother me to import parts I need from the USA.
    I am fairly handy so I could learn to service them myself? I am familiar with O2 sensors and know they need regular replacement but what other commonly perishable parts are there that start getting expensive?
    To narrow down my questions there are a lot of used RBís here for sale around the $2-3k mark.
    This could be a good saving but I may find out I have to replace $3k worth of parts. If I go down this path can you advise what to look out for? If I buy new I guess I am going to get a good run from a unit before expensive replacements are needed. I will try to find a rebreather diver over here that needs a buddy perhaps so I can absorb more info. It is harder over here, not as many people are doing it in my area. Can you also advise the best nuts and bolts bible to study RBís that would be a practical starter for me? Not getting in to the rocket science of Trimix just yet (but maybe one day). Cheers guys and thanks for the feedback.

    P.S. Question: If I have an unobservable triple O2 sensor failure or electronics, with O2 toxicity there are usually some tell-tale symptoms, at least in shallower water, I have experienced high PPO2 (I donít make a habit of it). I imagine hypoxia has no warning and is straight out death? With CO2 toxicity would a warning sign be shortness of breath? I am just interested, not about to experiment with myself.

    BAZZA... I looked up some footage of the Hollis, it would be perfect (and safe) for nitrox but from what I see from you tube it is far from bubble free, unless I could close the loop occasionally for a short time and then do a complete flush, this would be a great method but I donít know enough yet, this could probably be a dangerous practice? I have spent years collecting fish on OC so I donít know the difference yet between the bubbles scaring fish from OC to SCR to CCR because I havenít tested an RB to find out. The most important thing for me is not scaring fish rather than long dive time on one cylinder. Just recently I have been using a 50 litre cylinder with nitrox and hookah hose and I also have scuba cylinders. Before this I spent as long as possible on SSBA petrol driven hookah compressor. I have no limit to dive time as it is, barring my decompression limits. I can come up after a couple of hours have some surface time and do a repetitive dive. I looked up your website already before I joined RB forum, thanks for the offer to help pick out a unit, sounds like you can help save me some dollars I appreciate it, I will give you a call.
    Having found my way to CCR from SCR, I say don't bother, you will be disappointed with the amount of bubbles and you will not have as good a quality of interactions with wildlife. You still have to pack a scrubber, you still have critical parts like check valves and a mouthpieceDSV to maintain and a loop to clean at the end, I just don't see the point. Plus, nitrox is not available in far flung parts of Indonesia and PNG. Any place with a hospital or a welding supply means O2 can be arranged.

    Any CCR without a solenoid is easily user serviceable, perhaps with the exception of the pressure sensor. Some ECCR's have user replaceable solenoids, others do not.

    As for toxicity symptoms, any decent CCR training manual will provide descriptions of symptoms. Problem with them is there is usually little to no warning and by the time you know what's wrong it's often too late to effectively remedy the situation. In my humble opinion, the best way to stay out of trouble is to know how your rebreather function and practice awareness, little things like expecting the solenoid to fire at regular intervals if you are at a steady state workload. Expecting it to fire if you ascend a few feet, etc. Tripple sensor failure is very unlikely if you test for current limiting at 6M and the unit calibrates properly. Most ECCRs track sensor performance during the dive and will vote a sensor out if it does not respond as expected given the depth and O2 addition...

  3. #13
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: Is a rebreather for me

    Quote Originally Posted by Jeff Pack  View Original Post
    get a KISS GEM, uses your existing OC gear, single tank, turns a faber 95 into 4 hours of diving, with the tiniest bit of bubbles.

    If you were tech diving,then CCR< but for recreational use, an SCR cant be beat. I dove one for a year until I transitioned into tech diving.
    How's the WOB on the GEM? Not expecting meg-like performance but I found my KISS Sport to be tiring after an hour or so and my chest would actually hurt after a long dive.
    Cheers,

    Dave....

    www.wedivebc.com

  4. #14
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    Re: Is a rebreather for me

    To be Honest, very good, not like the meg, but close, although I never did get it into the positions I have with my meg. But I was doing 4-1 hour dives a day on it,with no fatigue.

    Edit
    I had the user packable scrubber, not the extendairs

  5. #15
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    Re: Is a rebreather for me

    Hi There,

    If you decide on getting a unit, I would suggest find a used one first to see if you like all the new changes in the way of diving, pre and post.

    Best regards,
    Chett. L

  6. #16
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    Re: Is a rebreather for me

    Ccr can be very beneficial for your work..
    On air diluent your depths are a sweetspot and the marine life encounter is a game changer

    Just try it out.. if you start with a used classic inspiration you should get away with less than 2k including training nowadays

  7. #17
    RBW Member Dive Africa is an unknown quantity at this point Dive Africa's Avatar
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    Re: Is a rebreather for me

    Quote Originally Posted by Jeff Pack  View Original Post
    To be Honest, very good, not like the meg, but close, although I never did get it into the positions I have with my meg. But I was doing 4-1 hour dives a day on it,with no fatigue.

    Edit
    I had the user packable scrubber, not the extendairs
    Get the best of both worlds i.e. a very small Meg aka a Pathfinder.

  8. #18
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    Re: Is a rebreather for me

    except for what he'll pay for one, even used.

  9. #19
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    Re: Is a rebreather for me

    cheap AP unit ,

    stick a hud and a trickle valve on it ,

    also i see your from oz , so maybe look up what hoops you need to jump through,
    Last edited by Gobfish1; 6th February 2018 at 09:51.

  10. #20
    RBW Member chaetodon is an unknown quantity at this point chaetodon's Avatar
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    Re: Is a rebreather for me

    Quote Originally Posted by silent running  View Original Post
    Having found my way to CCR from SCR, I say don't bother, you will be disappointed with the amount of bubbles and you will not have as good a quality of interactions with wildlife. You still have to pack a scrubber, you still have critical parts like check valves and a mouthpieceDSV to maintain and a loop to clean at the end, I just don't see the point. Plus, nitrox is not available in far flung parts of Indonesia and PNG. Any place with a hospital or a welding supply means O2 can be arranged.

    Any CCR without a solenoid is easily user serviceable, perhaps with the exception of the pressure sensor. Some ECCR's have user replaceable solenoids, others do not.

    As for toxicity symptoms, any decent CCR training manual will provide descriptions of symptoms. Problem with them is there is usually little to no warning and by the time you know what's wrong it's often too late to effectively remedy the situation. In my humble opinion, the best way to stay out of trouble is to know how your rebreather function and practice awareness, little things like expecting the solenoid to fire at regular intervals if you are at a steady state workload. Expecting it to fire if you ascend a few feet, etc. Tripple sensor failure is very unlikely if you test for current limiting at 6M and the unit calibrates properly. Most ECCRs track sensor performance during the dive and will vote a sensor out if it does not respond as expected given the depth and O2 addition...
    Thank you for the tips, this is increasing my knowledge. There is a lot to learn and experience goes a very long way. I had some thoughts previous that the solenoid would make sounds when it kicks in. Your post has confirmed that to me. It is the experience of these little things that all add up to knowing the ins and outs of your gear. One guy mentioned to me today how the dynamic is different to OC or SSBA. When I have been taking a breath or exhaling on OC, I have been so used to unconsciously altering my buoyancy that the RB is going to feel very strange until I am used to it. I did know this superficially but now its hit home how different this will be. I havenít even been near a CCR yet! You asked me about work load and yes sometimes I am in current but what really gets me panting is sometimes I need to do a quick sprint to catch a fish. Most of the time its relaxed and stalking but if one behaves tricky or bolts away I need to exert for a short while to catch it. This may be a dozen deep breaths before I can relax once again. Something to consider, or maybe for tricky fish I have to let it go if using CCR. Whatís the amount of breath cycles if I am in a relaxed state before the system needs to dump? Also what is the scenario under a heavy workload? I guess this varies greatly on the depth I am at but I am interested to know how much rate the diluent and the O2 is used up. I have a great deal yet to understand about the transition of the gases. I wish I could spend a day going through this with you, I think I could pick up a great deal. The big problem I have here is doing a courses is $3000 and I will be treated like a freshman. I need to do 100 hours advanced nitrox before they will allow me to go near CCR. To fill you in I am an ADAS approved diver, It is a commercial qualification here, the work place health and safety part of the government made us do it after years of diving without the need for qualifications. After this we have been diving so long professionally we just took upon and started using O2 years ago without getting certification etc. With all due respect to recreational and tech divers Itís a different world for a pro diver. I will get flamed for saying this but a certificate means nothing to me personally, a piece of paper is not going to keep me alive down there. I understand all this from the teacherís aspect, it is to do with liability issues and also they need to earn their living, plus itís so expensive because of the stigma surrounding CCRís. I naively didnít want anything to do with RB for my whole life because I thought they kill. New people learning, I agree should do the right thing and get their certification but I am 60 and have been doing this forever and will be treated as a novice if I sign up for a course. Itís a dilemma for me but I will see what I can learn and then weigh it up from there.

    I looked up Prisms and there doesnít seem to be too many over here for sale. There are megs, optima 2, Poseidon VI, and inspiration classic which a couple of guys suggest to try out first because they are cheap. (Bazza from Southern Cross recommends APD Evolution Plus, or JJ-CCR. These are probably newer expensive models) Whatís your opinion, are any of these similar to the Prism 1 you mention? I like your comments of considering more toward MCCR or basic ECCR than too much integrated sub system technology. But considering my workload, I guess you mean I would need something simple thatís still quickly responsive if my activity is sporadic?
    Are there any other units you recommend I look at? So many different brands???

    P.S. I also came across a Queensland Grouper on OC or Hookah, I forget. He was behind the stern of a large sunken barge we dive on. He was curious to some extent and we were facing each other about 20-30 feet away. I slowly edged closer until I got about 12-15 feet away. He spooked and turned on a dime, flicked his tail and shot off at unbelievable speed 30 knots or whatever. The shockwave hit my chest and head like a powerhead going off. Wow from that distance! Now I can appreciate what happened to you being next to the big fish when he did that. It must have felt like a submarine depth charge going off or what?? Ha ha.

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