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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
    UKD Supporter

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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.

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