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BOV with MAV and/or ADV - thoughts?

Discussion in 'Rebreather Diving' started by stuartv, Aug 13, 2018.

  1. stuartv

    stuartv Seeking the Light

    # of Dives: 200 - 499
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    I get all that. But, you guys seem to be forgetting that there is nothing about having a BOV that stops you from switching directly to your big BO bottle - if you can. At least, as far as I know. I DO recognize that I really know just barely enough to be a danger to myself.

    My understanding is that having the BOV plugged straight to the dil bottle is only different than having no BOV at all in that it gives you just that little bit longer time to try and get yourself under control in order to switch to the big BO bottle.

    From what I read, it seems like a BOV is not just for newbies. I don't know the details of @tomfcrist's experience, but I'd guess he's not a CCR newbie and he was talking in a recent thread about the difficulty of switching off the loop during a CO2 hit. It seems to me that if a BOV gives you even 30 seconds of dil to breathe while you're trying to switch to real BO, that could be extremely valuable. No?

    Anyway, I also don't want this thread to be so much about HOW to plumb a BOV. I'd like to try and stay focused on if there is any real issue with a BOV with MAV versus a regular BOV and chest-mounted MAV (or wherever).

    Regarding a place to plug in offboard how do they do that with the DR? Is there just a hose somewhere with a male QD fitting? Hanging down your chest, in the same area as a normal MAV would be? I assume you're not trying to plug an offboard hose into anything attached to your mouth.

    As for the ADV on the rEvo, if you added a BOV with ADV, would you really bother to disable the built-in ADV? Is there a downside to just leaving it as is? You said it's bad, but why? Does it pop off unexpectedly, when you don't want it to? Or is it just hard to activate, so with a better one, the built-in would just never do anything?
     
  2. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Come ON Stuart. Don't turn this thread into BOV vs DSV.... Resist. :)
     
    stuartv likes this.
  3. Superlyte27

    Superlyte27 Cave Instructor

    # of Dives: 5,000 - ∞
    Location: Florida
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    A few answers:

    Regarding the ADV on the rEvo. It’s hard to activate to the point of being useless. In comparison, on the Optima, I can scooter down 200’ as fast as my scooter will go and when I get to 200’ my loop volume and PPO2 will be perfect. I’ve yet to dive another rebreather that will do that.

    If you plumb your BOV into your bailout... it’s not just 30 seconds and an empty bottle. You can stay on the BOV at that point.

    In reference to the aforementioned CO2 hit. My argument would be that if you got to that point where breathing was so elevated, you weren’t paying attention. You should have resolved the issue long before then.

    I’m currently bedridden due to a surgery. When I can, I’ll get you some pictures of the BoV. Conversely, if you talk to Matej at Dive Soft, or Anyone at Dive Rite, I’m sure they could send you some pictures. They are both very friendly and accommodating.
     
  4. Superlyte27

    Superlyte27 Cave Instructor

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    You guys know that these threads take whatever form they will take. As long as people are talking, it’s good for Pete Murray, lol
     
    The Chairman and stuartv like this.
  5. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    Actually, I really like the BOV vs DSV topic. I'm happy with my DSV, but I'm always willing to listen to other opinions...
     
  6. joshk

    joshk Barracuda

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    Define “real issue” here. You're moving some stuff to right in front of your face which may or may not be annoying. I doubt many people have a BOV with manual adds mounted since it's relatively a new product.

    Just no. Don't do this. Plumbing a BOV to onboard is a ridiculous decision and makes absolutely no sense unless you think your onboard is enough for a bailout.

    What is DR? My MAV blocks have offboard fittings on them which gives me a place to add offboard gas.
     
    lv2dive and rjack321 like this.
  7. joshk

    joshk Barracuda

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    Two things I like about the Shrimp over whatever stock DSV you have. First, you can disconnect it and actually check the mushroom valves. It's easy and dries way faster. Second is you can easily switch to open circuit to blow your nose out at around 120 minutes on a cave dive :D

    Second stage bungeed around your neck on a short hose is a good alternative.
     
  8. Superlyte27

    Superlyte27 Cave Instructor

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    DR = Dive Rite

    The other thing to consider is the mouth fatigue of a BOV over DSV on fast scooter dives in high flow. I hate them.
     
  9. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

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    @stuartv It's normally done like the picture below. This is from the Fathom CCR page, but it applies to just about every CCR with backmounted counterlungs.

    You can see the MAV block on the left shoulder which has a female QC6 on the bottom of it. That goes out to the MAV addition port on the t-piece, and the other goes to the BOV. Your bailout bottles have male QC6's and plug into that. That way whatever you are adding into your breather is also what you can switch to on your bov. In this unit IIRC both onboard bottles are O2. Could just as easily be wing/suit inflation, or if using something like lp50's or lp85's, could also be your dilout bottles similar to the GUE ccr configuration.

    With an iBov, you'd have the one hose going up to the bov/face mav and obviously wouldn't have the add block there. You could have a splitter to fill the wing, or just have the end of the hose terminate in the QC6. On the iBov specifically, watch their youtube channel, lots of good videos on that product there

    14701040_1216990105027215_4064343643175627436_o.jpg
     
  10. doctormike

    doctormike ScubaBoard Supporter Staff Member ScubaBoard Supporter

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    I need to sell you my 3D printed invention:

    Hose Hanger.jpg

    I need to call in some Singulair for you.
     
    rjack321 likes this.

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