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Wibble's CCR odyssey

Discussion in 'General Scuba Diving' started by Wibble, Jul 5, 2020.

  1. Wibble

    Wibble Fish don't talk
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    Just passed a milestone of my first 50 hours of diving on a rebreather. So much more to finesse and learn.

    it’s been a lot of fun and has resulted in many changes of mind in the way that certain techniques and kit which are of moderate use when diving open circuit become very useful when diving CCR. For example big and sturdy reels which are a moderate convenience in OC become almost essential or the very least exceedingly useful when diving CCR.

    As Barry pointed out some time back, it’s the ascents which are the major challenge. They’re just so busy on CCR. The addition of a large reel massively simplifies decompression stops, effectively damping any small vertical changes.

    Enough about the skills, it’s the amazing flexibility that CCR brings to diving. The marginal gas costs are tiny compared with open circuit. This means that all dives can be helium dives and there’s much less focus on gas planning and optimisation — pick a standard gas and pretty much use it for all dives. Have settled on 18/45 for now and at around a fiver a dive it’s a no brainer. With the Revo consuming only 1.3kg of lime costing less than a fiver, again there’s no reason to eke out the scrubber.

    Diving is so much more pleasurable when diving CCR. Aside from the lack of bubbles roaring past one’s ears, no bubbles means the fauna isn’t disturbed, so fish swim around you, not away from you. When inside wrecks there’s no bubbles to disturb the space above you, so no rust snowstorm. There’s also little gas stress leaving one the time to get on with the dive, if you get stuck or lost, just chill — don’t worry, be happy.

    The rebreather demands respect though. You can’t skimp on preparation which means allowing for an hour of preparation the night before. When diving it needs constant monitoring. I’ve settled on mainly running it manually with the computer as backup — manually changing setpoints, manually injecting oxygen and diluent as required to maintain the desired setpoint, I.e. keep the machine set to 1.2 and run it at 1.3 or 1.4 as required, and running the deco a little higher if it’s not too long.

    Sidemounting the bailout and deco stages keeps them well under control. Out of the way and not swinging around to catch on a wreck. Generally dive with two stages to minimise bailout worries.

    Really not regretting my selection of the Revo. Love the engineering, simplicity and redundancy. Two scrubbers, who’d have thought it! The Nerd is an amazing tool, can’t recommend highly enough. Five cells... removes cell angst, fine by me.

    So much more to finesse. Can work on the during the next 50 hours! Will be taking it underground when the sea's off limits.


    Utterly delighted with the past three months of intensive diving in such a strange year. Looking forward to many more.

    Many thanks to all people on here who’ve helped me on this journey.
     
    JimmE, Harvey-NG, jps and 3 others like this.
  2. Wibble

    Wibble Fish don't talk
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    Small update on the sidemounted stages. The sidemount configuration works exceedingly well, keeping the cylinders out of harms way whilst allowing fast and easy access to the bailout.

    The stages have a standard "handle" mounting with two large bolt snaps. The pipe (handle) is rotated 45 degrees around the cylinder to facilitate clipping on the bungee.

    Sidemounted bailout 3.jpg
    Sidemounted bailout 1.jpg

    As mentioned previously, the harness has two chest D-rings each side. The lower one is used for clipping off the stages (and the backup torch) and will be pulled flat when the bungee's attached, which obviously makes it difficult to use the D-ring for clipping off the myriad other crap to your chest. Thus the top D-rings are used for that (with the bolt snaps shown below). Also shown below is the "get me out of my harness" loop, making me more self-sufficient de-kitting on the boat.

    Revo harness 4.jpg


    The stages have both clips used, so they're basically bog-standard stages although using LH & RH modular valves, so can be handed off to any other diver if necessary. The top clip is clipped to the lower chest D-ring and remains in place. It's possible to undo this before attaching the bungee for that full sidemount experience, but it's not necessary on my config. The lower stage clip is attached to a "Billy" D-ring on my waistbelt (can be seen on the top picture).

    From the pictures above, you can see the LH cylinder (ali7 232 bar) has both clips pulled back by the tension of the bungee. The bound/whipped piece of bungee is a simple handle: grab it and pull it off the modular valve (this is a lot easier than a tight loop which you end up tearing your dry gloves).

    I know that there's some slight tweaking to be done with the position of the waist D-ring, but that's all the pleasure of farting around with sidemount, the seemingly never-ending tweaking to get the kit "just so". But once done, it's ninja every time!
     
    jps likes this.

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