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New to rebreather diving

Discussion in 'Rebreather Diving' started by QAQTAT, Aug 3, 2020.

  1. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

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    @doctormike you can't get the NERD controller though right? Only monitor? Such a shame if only the monitor
     
  2. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    I mean, the NERD it is what it is - a HUD that gives you PO2 information in number format, and other information as well. The fact that it doesn't function as a second controller is more of a JJ design decision than a Shearwater issue.

    Since these things run on DiveCAN, I guess there is no fundamental reason why Shearwater couldn't put the guts of a JJ controller that is now in a Petrel case into a NERD case - the controls are the same. But the JJ is not designed to have two controllers, so I guess your concern is more about the rebreather design, right? And then you would have the issue of voting if for some reason they were getting different data. One of the things that I like about the JJ is its simplicity (which of course is a tradeoff to some divers).

    Right now, if you have a handset controller failure, setpoint just switches to 0.7 from the head. I guess if the NERD could act as a controller you could continue the dive? I would just ascend.
     
  3. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

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    @doctormike I'd dive it with a NERD as controller and a Petrel monitor, not as redundant controllers. REVO has that as an option and SF2 was doing some work on it but don't think it ever took off.
     
  4. flymolo

    flymolo DIR Practitioner

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    Also wondering this
     
  5. taimen

    taimen ScubaBoard Supporter ScubaBoard Supporter

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    I think @rjack321 nailed it above.
     
  6. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Gotcha... What's the advantage of that?

    I actually find it easier to work the controls on the handset than on the NERD, and since I don't change setpoints that often during a dive, doing it on the Petrel seems fine. But I'm always willing to try new things!
     
  7. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

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    means you can tuck the Petrel away somewhere to keep your arms free. Similar to what we do with the controllers for the Meg's since they're basically useless unless you're changing setpoints and the one that you are always looking at is the "master" so you only look down at the "slave" if something goes sideways.
     
  8. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
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    OK, maybe a different style of diving. My petrel is on my wrist and I don't notice it being there unless I need it - it certainly doesn't mean that my arms aren't free. And having redundant PO2 reading is good, why do you want to tuck that second display away somewhere in case of a HUD failure?

    Again, not trying to be argumentative, just trying to understand. One of the things that I like about the JJ is that the design decisions seem very thoughtful and justified. I think that it would be easier to change a setpoint on my wrist than on my loop, assuming that I'm only doing it twice during the dive, or maybe for a dil flush.
     
  9. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
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    I dive manually, so I don't change the setpoint at all during my dive, but I can't imagine it would be appreciably more difficult on a NERD. With digital communications, you don't have the same need for redundant monitoring to validate during the dive. The sensors are going to the same ADC board on the JJ so you aren't reading a different group of sensors. The ADC conversion is going to send the same signals to the SOLO board and the OBOE board. Since communication is now 2-way, and there are no isolator boards or any of that nonsense, the only reason for the secondary monitor while on the loop is in case the primary fails, not to validate like it used to be. You certainly want something up in your face, so may as well make that everything you need and then the other can get tucked away if you don't want the cable on your arm, or just left on your arm. Second reason to have it is in case you bail out and don't have a BOV, you'll then want to not have to pull the loop down every time you need to look at the computer.
     
  10. flymolo

    flymolo DIR Practitioner

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    Interesting - would someone mind describing the KUR-style configuration? Guessing that's something like side mounted lp85s for bailout and al30s for onboard diluent and o2?

    I'm not particularly well-versed in blending, but what about the 50s makes them hard to top up with a small booster?
     

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