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Lightest and most popular RB

Discussion in 'Rebreather Diving' started by Compressor, Jul 12, 2018.

  1. kensuf

    kensuf Cave Instructor

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    I absolutely love the HUD.
     
  2. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    HUD's are definitely not something I find intrusive at all, though I wish the one on my meg could be viewed when it's bright out. It's pretty much useless on shallower OW dives since it gets washed out by the sun
     
  3. rddvet

    rddvet DIR Practitioner

    # of Dives: 50 - 99
    Location: Florida
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    Good to know. They seem distracting, though thats their job
     
  4. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    it's why I dive my meg at 1.1 and only 1.1. Anything else is obnoxious. I get 1 blink, 1 blink, 1 blink, plause from the green light. If I see a double blink anywhere it means that it's up to 1.2 and is really easy to spot, and if I see the red light come on, then ppO2 is too low. Conveniently 1.1 is a perfectly reasonable ppO2 to run, but anything else is truly obnoxious to me so unless I'm on deco, it stays at 1.1
    Some HUD's are different though and give a "green is good" "red means look at your handset"
    The Liberty holds a solid green light at 1.0, then blinks the green light for 1.1 and up, and blue light for .9 and down in smithers code. If I were diving a Liberty, I'd probably dive it at 1.0, again because it's least intrusive and then I can easily see the change from green to blue when it goes down, or solid green to blinking if it goes up.
     
  5. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
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    I wasn't implying that that was unique to the JJ, I was comparing a rebreather to a set of doubles.
     
  6. kensuf

    kensuf Cave Instructor

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    My point was that 2x 3L bottles is not something that is unique to the JJ. Almost all CCR's use that arrangement. The only CCR's I'm very familiar with that do not use those is the Optima, which uses the stubby 4L's, and the Sidekick/Sidewinder (off-board DIL and usually 2L Oxygen).
     
  7. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: New York City
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    I think that we are saying the same thing
     
  8. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

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    Location: NC
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    One of my frequent team mates has a Sidewinder and it works well for him, but it is heavier over all than my Sidekick, takes up more space to pack and is much more involved to assemble.

    With my Sidekick I can bubble wrap the O2 reg, MAV, Petrel and DSV and pack them in the scrubber, which is inserted in the counter lung. I separate the MAV and hose from the O2 reg however to prevent TSA from regarding it as a blunt object that could be swung. That leaves just the two loop hoses which lie along side the rebreather in a 22" x 9" x 9" carry on bag with 5" to spare in the width dimension. That leaves room for a de-valved 2L O2 bottle and the dilout regulator. The dilout bottle and, if needed, a stage are sourced on site.

    The Sidekick is also flexible in terms of being able be used as a Sidemount CCR with the dilout sidemounted, or as a sidemount CCR with the dilout carried as back mounted doubles (independent or isolator manifolded) using something like the Nomad XT with stabilizing plates.
     
    tbone1004 likes this.
  9. 688ClassRebreather

    688ClassRebreather Angel Fish

    # of Dives: 1,000 - 2,499
    Location: Maryland, USA
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    I agree... but I would highly recommend Tom Anderson. He is an excellent instructor.
     
  10. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
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    I don't find a HUD to be distracting, but I'm also ambivalent about mine, at least on my KISS Sidekick.

    I got it in order to have redundant loop monitoring, and I also found it was convenient for monitoring the loop in small side mount passages and in low viz. On the other hand over almost 300 hours I've never been in a situation where it really made a difference.

    IMHO, you really have to run it the way Tom has described so that it emits a single flash or a steady light, or else you start to ignore it. For example, I'll run my loop at 1.2 on deeper dives to minimize the deco, and at 1.2 my HUD gave (note the past tense, more on this later) 2 green flashes. However, when that is the case, If one cell indicates a PPO2 of 1.25, then you'll get three flashes from that cell and 2 from the others. That more or less normalizes you to seeing three flashes, so before you know it you could be running as high as 1.34 and not have it register in your brain that something is off. I found I was more likely to notice the lack of green light from a low PPO2 (an amber flash at 1.0, a single red flash at .9, 2 red flashes at .8, etc), but ultimately unless you are running it with it at 1.0 and a single amber flash, what you're really only cueing on is that a whole lot of flashes is bad.

    Since almost nothing happens real fast on leaky valve rebreather like a KISS, if you have developed the habit of checking the PPO2 readings on the computer every 4-5 minutes or so, the HUD will never tell you anything you don't already know. Which makes the HUD extra baggage and a source of potential failures. I found that the splitters that allow the cells to run both the Petrel and the HUD actually caused problems with millivolts sent to each. The potting on the sensors degraded fairly quickly and I ended up having to re-pot mine to prevent voltage loss across the connections. Even then, they made low cell readings more likely once there was significant moisture in the head (condensation after a few hours of diving, etc). In effect my plan to use the HUD to backstop the already reliable Petrel actually created a problem due to the nature of the splitters.

    Then things got worse. My HUD decided one day that 1.2 was now the normal "amber" reading. It would still calibrate at a PPO2 of 1.0 and flash amber, but then shortly start flashing two reds to indicate the 1.0 PPO2 and flash amber once the Petrel was showing a PPO2 of 1.2. That actually worked well for me for awhile given that I liked a PPO2 of 1.2 on deeper dives. In did ask Shearwater about it at DEMA, thinking I had inadvertently button pushed it there. However Shearwater claimed the HUD electronics can't change the PPO2 for an amber reading (even though it has). They also indicated that since the unit is fully potted they also can't fix it if something happened inside. They suspected an issue with the wiring and they were probably right as eventually one of the cells stopped reading, which results in a red/green flash. That was annoying and at that point I removed it.

    The hole in the head for the HUD's cable uses the same thread as the old 1/2 LP port plugs that Aqualung and a couple other companies used for a short while. Consequently, my Sidekick now has a 1/2" to 3/8" LP port plug adapter and a 3/8" LP port plug in it now. I did have to chuck the adapter in my lathe and turn a couple threads off it as the threaded portion of the adapter was quite long and there wasn't enough clearance under it otherwise.

    The HUD has been off the unit for about 50 hours now and quite frankly I'm not sure I'll send the HUD in to Shearwater since I don't miss it, or the splitter related issues, at all. It's just not worth the potential expense to fix it.
     
    JohnnyC and tbone1004 like this.

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