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So I bought this pile of plumbing parts...

Discussion in 'Rebreathers Closed and Semi Closed Circuit' started by Doomanic, Feb 28, 2016.

  1. Doomanic

    Doomanic Dinosaur Wrangler
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    As some of you know, I bought a bereaver recently and I thought you might like to read about the trials and tribulations of a novice CCR diver.

    It all started about 7 years ago, when I first saw a Classic in my LDS. "What is that?" Says I. "It's a rebreather" says the shopkeeper and gives me a very brief overview. "Wow! I want one those!" Says I.
    Ever since, I have been on the lookout for a bargain Classic and while a few have come up, they never seem to coincide with me actually having any money... :(
    That changed this December, when some drunken eBaying whilst on a dirty weekend in Amsterdam with the Long Haired General resulted in me being the proud (?) new owner of an antique. I got it for an absolute bargain price, so much so that I was expecting to be told to fcuk off when I tried to arrange delivery, but just after Christmas the UKMail man knocked on my door and presented me with a huge package...
    Task number one was to strip, clean and disinfect the breathing loop as I had no idea when it was last done, then it was off to Stoney to meet up with a mate who knows far more about rebreathers than I do. The deal was simple; we were meeting up for him to check it over, if for any reason he said it wasn't fit to dive I wasn't to argue. Unbelievably, he said it looked OK, so we went for a 40 minute bimble on the 6m shelf. We headed over to the Gresham and then back to the cockpit. At this point I thought we might be going down the road to the 20m shelf, but was promptly turned around and had a finger wagged me. :D Suitably chastised, we headed back to the steps and I experienced my first "Oh fuck" moment; ascending is harder than you think, I got to 3m and rocketed to the surface. Oops.
    No harm done, we had brekkie and a chat and got back in the water. This time we headed past the cockpit and down the road to 10m where we did some ascents up the wall to 6m. First attempt was ropey, but after that it went fairly well.
    All in all I left after a couple of satisfying dives, happy that I hadn't bought a complete basket case.

    We met up a couple of weeks later for another dip but unfortunately my buddy had some issues with his unit so had to leave with one of his mates that had tagged along. The dive plan was to head down the road to the 20m shelf and visit the bus, Stanegarth, Defiant and Belinda and head back to the road for a gentle ascent. My new buddy forgot about the last part of the plan so we ascended up the wall to the 6m shelf. My previous practicing paid off and I made a reasonable attempt the ascent.

    I should say that at this point I had absolutely no idea of what to do if things went wrong. I knew from the AP manual that knowing my PPO2 was the the most important thing, but not how to deal with it if I had a problem other than bailout and get to the surface. This is not something I recommend; training is vital, and that's the next part of the tale...
     
  2. Zubar

    Zubar Active Member
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    Well Lordy lordy, a write up begins!

    Thanks Doom.
     
  3. hawk

    hawk Doing It Rong
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    Keep it coming :)
     
  4. Wibble

    Wibble Fish don't talk
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    So what is the buoyancy control like? Given that all the bags of air are constant, this puts the onus on your wing control. How's that for doing fine adjustments, say a couple of inches?

    Also, where do you fill the wing from - is it your "diluent" cylinder, or do you use another for that?

    Fascinating insight.
     
  5. Doomanic

    Doomanic Dinosaur Wrangler
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    The same, but different. There's more bags of gas to control and you can't make micro-adjustments with your lungs, but apart from that is very similar to OC. Constant depth changes are a pain, so the squarer the profile, the better.
    It's a little more difficult, but once neutral it's easier to hold.
    Yes, wing is filled from the Dil and is the primary consumption of gas from that cylinder.
     
  6. Dave Whitlow

    Dave Whitlow Well-Known Member

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    Nice starter Dom :)

    So long as you are thinking about the physics before it affects you buoyancy isn't hard.

    Yes, you will learn to swim round things rather than over and under things (I miss that)

    The wing is filled with dil so you need to use minimum lead and you should not need to waste dil in the wing during the dive. Useful on the surface (although you can inflate the hard way if you are really cheap)
     
  7. Wibble

    Wibble Fish don't talk
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    Do some 'breaver divers use a wing inflation cylinder? I ask as I once saw an inspiration with four cylinders - one of those G-Box thingies. I think that one cylinder was used as a bailout.
     
  8. Dave Whitlow

    Dave Whitlow Well-Known Member

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    Never seen one with a wing cylinder as most folk find the wing is only needed for surface buoyancy.

    I have a G-Box and for bigger dives carry four 3 litre cylinders; diluent, air/nitrox, oxygen and more oxygen. The wing runs off the diluent, as does OCB, and the suit off the air/nitrox. The air/nitrox and second O2 have a 2nd stage on them and I can also plug the second O2 in the O2 manual add valve (MAV). For those dives I'd also be carrying 2 AL80s; trimix with LP hose I can plug into dil MAV and rich nitrox with LP hose I can plug into O2 MAV.
     
  9. hawk

    hawk Doing It Rong
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    Kin 'ell - I get the arse with having to service and O2 clean 4 tins!
     
  10. Dave Whitlow

    Dave Whitlow Well-Known Member

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    :eek: you really wouldn't like my garage! I mostly fill them myself so they aren't kept in o2, although they do get a hydro when due.
     
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  11. hawk

    hawk Doing It Rong
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    I can see the benefits .....
     
  12. Doomanic

    Doomanic Dinosaur Wrangler
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    Buying a bereaver has turned me into a woman; I just can't to seem to stop shopping for bits for it!
     
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  13. Dave Whitlow

    Dave Whitlow Well-Known Member

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    :oops: these things happen. been looking at booster pumps yet ?
     
  14. furryman

    furryman hmmmm
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    Wibs has a nice pair of 300 bar twins to use as a high-pressure air-bank...
     
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  15. Doomanic

    Doomanic Dinosaur Wrangler
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    Yes... Gulp.
    I have a set of Faber 12s on the way complete with 21/35 to act as a bank. :D
     
  16. Dave Whitlow

    Dave Whitlow Well-Known Member

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    Nice. Same as I started with, a the fill intended for the Moldavia if I recall correctly which lasted a couple of months as dil.

    Boosters don't need to be very big ;)

    [​IMG]
     
  17. Wibble

    Wibble Fish don't talk
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    Ooooo kit envy.... Isn't that about £2k's worth?
     
  18. Dave Whitlow

    Dave Whitlow Well-Known Member

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    Probably a fair bit less and I bought it second hand from a dive buddy who was upgrading to something hugely bigger, faster better and which pumped to silly pressures.
     
  19. Doomanic

    Doomanic Dinosaur Wrangler
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    It's time for the next instalment in the Doom empties his bank account saga; MOD1. It's not going to be a full course report, more a brief overview, as I owe Garf a full course report for Fundies and I don't want him sulking...

    At this level it's said that you should pick the instructor not the agency, so with that in mind I sent out some feelers to some guys with good reputations. One priced himself out of the market, one was out of the country, one wouldn't combine MOD1 with a trimix ticket and one couldn't give me firm dates for the course. That left one who, if truth be told, was my number one pick; Mark Powell. Venue was NDAC.

    MOD1 is basically one day explaining how to prepare and maintain the unit and 4 days showing you the many ways it will try to kill you and how to deal with them. The first wet day (day 2) was pretty easy, mostly just swimming around getting a feel for the unit with a few simple drills on dive two. Day 3 was more of the same, but with more drills, and each debrief went the same as the last; "That went OK, but you can do better, we'll do that again on the next dive." Day 4 just piled on the pressure, but it was all going fairly well at this point. Mark was pushing me hard and I was learning a lot. He's certainly not an easy option. All drills had to be conducted neutral and stationary, unlike the muppets we saw on another course who were kneeling on the bottom doing bailout drills...

    Day 5, the last day, and it's all to play for. As I'm doing Helitrox combined with Mod 1 it's about to get complicated, and expensive. Mark offered to do a Vision crossover to go with my Classic ticket, so dive 1 is all about failures using the HUD lights, but it's also the qualifying mix dive. We'd done some gas calcs and worked out that my ally 11 would last 22 minutes if I bailed out at 45m while breathing at an elevated 45lpm. The dive plan we were following was 48 minutes, so I had to thumb the dive at 26 minutes (22 minutes TTS). We spent longer than planned at 25m doing the HUD skills so by the time we got to 45m and I was settled I'd missed the 26m turn point (by 30 seconds). There was much finger tapping on computer and we started the ascent, which wasn't my best effort and predictably Mark said we'd be doing it again at the end of the last dive.

    Ah yes, the last dive. Probably my worst experience under water. Ever.

    So, day 5, dive 8. Rescue an unconscious diver. To say it didn't go according to plan would be an understatement...
    Plan is to find an unconscious diver (Mark) at the back if the single decker bus (18m), raise them to 15m, swim them to the shot line and ascend, using the shot as a visual reference, to 6m with stops at 12m and 9m.
    It went rather wrong with Mark and I parting company at 6m; him positively buoyant, me negatively buoyant. I sank like a stone. My ADV (automatic diluent valve) was turned off so my counter lungs compressed and I couldn't get a breath. I tried to turn it on, but missed and carried on sinking. I tried to add gas using the MAV (manual add valves) but the compressed lungs effectively sealed them closed. I'm now at 12m and it felt like I hadn't taken a breath for hours. At that point I bailed off the loop on to my trimix bailout and chugged my way through a quarter of it calming down. To Mark's credit, he'd sorted himself out quickly enough to follow me down and when I looked up after taking my first OC breath there he was with a reg held out for me.
    I'd managed to close the loop when I bailed out, so at least my unit was still usable so after a couple of minutes I went back onto closed circuit and Mark signalled that we were going to try the drill again. It didn't go much better than the first attempt but we were out of time so the course finished with me getting a ticket for 30m on air diluent and the instruction to go away, practice and come back in a couple of months to redo the last 2 days for my Helitrox ticket and 45m.
    As a little kick in the teeth, my ascent from 20m at the end of the last dive was textbook, but too late.

    Mark is an excellent instructor and my inability to satisfactorily complete the course was down to me, not him, with my famous making-it-look-easy-and-then-fucking-up-the-last-day approach. With hindsight, I may have bitten off more than I could chew adding trimix so early on, but I was trying to avoid the expense and logistics of doing two courses. As it stands, redoing two days is much easier to manage than a whole separate course and I at least have the foundations in place.
     
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  20. furryman

    furryman hmmmm
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    sounds horribly familiar... :(
     

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