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Current State Of Rebreather Electronics

Discussion in 'Rebreather Diving' started by AdamSa, Sep 2, 2019.

  1. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    @wetb4igetinthewater so from what you sent me, here's the "Features" that they claim are different than the Shearwater
    wifi-who cares? frankly it's more annoying to connect to wifi computers than bluetooth since you have to usually disconnect from a wifi network to get on there, pointless
    wet switch-the shearwaters will activate via pressure switch after several meters so again, what's the point?
    LED flashlight-really? the screens are bright enough as is, don't want to deal with a lens on the front that is another major flood point, especially at deep trimix depths.
    Status Display LED-why does a wrist computer need a buddy light?
    Solenoid driver circuit-Shearwater used to have it with the Predator but has moved it into a separate part of the bus inside the rebreather itself. This is nifty for those that want to go the homebuilt eCCR route which Shearwater has said many times they want nothing to do with, but at the same time, the point of canbus is to have modules. This is going to put everything inside of the one case and at that point there is no point in digital communication because it isn't communicating with anything except itself....
    HUD driver circuit-why? the shearwater has the canbus centralized in the rebreathers, where JMI has put it in the handset. This is really useless IMO. Sure in a homebuilt you can have it connect to a HUD, but then if the handset fails you're screwed. In the Shearwater DiveCAN the bus is based inside the head and has separate cables going out to each device which makes it much more robust IMO. Less convenient since you have to put that board/battery either in the head or like Dive Rite did in a separate canister, but still more robust than leaving everything in the handset.
    Ambi cable gland-don't have a cable gland yet, but the Shearwaters have buttons on the sides so can easily be used on either arm and are on many commercially available rebreathers
    Stack timer-Shearwater has this on the divecan units, just not on the standalones but how can a standalone realistically have a stack timer when it doesn't know when you're on loop or off? either way it's a 30 second firmware update if enough people asked for it
    Real time clock with no need to reset time after battery change-the petrel and perdix both do this, and they also sync time with the computer when you download the log
    Accelerometer-nifty I guess, but why?
    gyro-same the shearwater has a compass, and I really don't need to know what pitch my forearm is

    Based on that, they don't do anything meaningful that the Petrel EXT doesn't do already, and some of the things that it does do significantly increase leak potential in the case design with excessive thru hull ports *i.e. why the Shearwaters don't have wet contacts, why bother having 2 extra thru-hull ports when having the pressure sensor turn it on a 2m is sufficient for 99.999999% of use cases*.

    Basically this is a fancy Predator controller or AV1, etc. and has a lot of superfluous features that I really don't see any benefit in having....
  2. wetb4igetinthewater

    wetb4igetinthewater Instructor, Scuba

    # of Dives: 500 - 999
    Location: Seattle

    You have made an incorrect assumption. That material I sent you, I haven’t read myself as I first wanted to get through some rebreather training first to have at least some basis to evaluate. Now I know not to bother!
  3. telemonster

    telemonster Barracuda

    # of Dives: 100 - 199
    Location: Northern Virginia
    Meh, the electronics on most seem outdated but there is no hints of any new developments in the pipeline?

    AFAIK the CanBus is vendor specific. Is the protocol open? There are $2 OLED screens that could be made into something like a readout only nerd2 type device (ppo2 of 3 sensors) for $5 in electronic parts (not including the housing and lens.)

    Would be interesting to see a unit that has integrated tank pressure reading (not wireless), optical loops and valves where the controller knows if the diluent and o2 tanks are on, pressure sensors that can tell if there is pressure from the tank to the solenoid. Knowledge if the solenoid firing is firing. Etc Etc Etc
    cathal likes this.
  4. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    If you want all that junk just buy a Poseidon.
    tbone1004 likes this.
  5. silent running

    silent running Manta Ray

    # of Dives: 1,000 - 2,499
    Location: Brooklyn, N.Y. U.S.A.
    Yes, and be prepared to miss dives when some of those sensors/bells/whistles fail to calibrate or read...
  6. RainPilot

    RainPilot CCR Instructor Staff Member

    # of Dives: I just don't log dives
    Location: UAE
    I have yet to miss a dive on the Poseidon in around 200 hours, except due to straight user error (I once had a cracked prepacked scrubber in the box and had neglected to bring a spare). Now that there is an official repack scrubber canister, I don't foresee missing any more dives.

    There's a lot of talk about how the unit "nannies" you, but it really isn't the issue it is made out to be (usually by people who haven't dived one)

    Sure there are a couple of design issues that I would do differently but for what it is intended for, it's perfectly fine. I don't expect that it is the best unit for long cave penetrations, but there are a LOT of big dives being done almost daily with the Poseidon (Richard Pyle and Brian Greene etc are doing 350-400' dives with them routinely on all their expeditions, and they aren't having reliability issues with them)

    Like any unit, it has its quirks, once a good instructor has shown these to you, you find that almost all the "failures" predive are from user error and are easily fixable.
  7. silent running

    silent running Manta Ray

    # of Dives: 1,000 - 2,499
    Location: Brooklyn, N.Y. U.S.A.
    Glad to hear you have had a good experience with the Poseidon so far, and I know you’re not the only one. But there are plenty of complaints on the net about not being able clear error codes, poor service, lockouts due to the internal calendar(!) and several reports of rebooting underwater. With over 40 system checks before entering the water, there certainly is a lot that can go wrong.

    IMHO, a good design is one where very few things can go wrong and there is more than one way to solve a problem. Battery voltage and hundreds of psi water pressure are a bad combination. The fact that there is no way to know your PO2 in the event of an electronics failure or dying battery, is bad enough without the unit being so technologically complicated. You can’t even manually add O2, you are completely dependent on the unit, except for bailing out.

    In my mind, short of a bad CO2 hit, staying on the loop is of paramount importance. Even if you bring the proper amount of BO, things happen in emergencies and your gas consumption will be elevated, you could be be stuck swimming in a strong current, or there could be some other stressor like bad leg cramps or being lost that causes your breathing rate to shoot up. Emergencies often cause people to make bad decisions, so I don’t want to ever have to BO off the loop in the first place, because then your time and options for solving problems will now be even more limited.

    Me personally, I think we should be talking about how to make CCR electronics/systems both simpler and more reliable, not more complicated and the diver more dependent on the electronics...
    Peter69_56 and BenjaminF like this.
  8. Reku

    Reku Solo Diver

    # of Dives: 5,000 - ∞
    Location: Great Lakes + Northern Florida + Marsh Harbor
    Your last paragraph is why after a long time of diving various CCR I've just gone back to a simple mccr and a needle valve and some fischer cable monitoring. Occasionally I'd run into solenoid issues/controller issues and I'm just not interested in dealing with any of that anymore.

    Things become simpler and more reliable when you remove unnecessary things.

    In another decade or so we'll see where things stand but right now nothing has changed for quite some years. Went from Analog to digital every so often you see some connector changes or additional cells like helium but that's really it.

    You could go CCR and pick mostly any newer unit and be fine. They all work pretty well. Some people like this or that but in the end it's all the same.

    Besides - your first unit won't be your last :D Once you come down the rabbit hole there's no way out.
    JohnnyC and rjack321 like this.
  9. silent running

    silent running Manta Ray

    # of Dives: 1,000 - 2,499
    Location: Brooklyn, N.Y. U.S.A.
    Yes, not surprised you went back to MCCR, simpler is almost always better. I love my Prism 1 because it is the simplest ECCR ever made and it suits the type of ocean diving I do most.

    Given the state of CCR technology right now, I think the simplest, most reliable set of electronics would be an MCCR utilizing the high output sensors used in the Prism and MK15s to drive an analog PO2 gage, and then also send the sensor outputs to a circuit powering a NERD. That way you would have the modern convenience of an integrated deco computer and HUD display, with the failsafe backup of an analog secondary which doesn’t require any power to display PO2.

    Given that needle valve MCCRs are here to stay, I don’t know why nobody has designed a unit like this. Some manufacturer must have considered the idea. But I guess if you go by what is offered/buying trends, maybe manufacturers believe that even CCR divers, who are almost certainly of above average intelligence, can’t get enough bells and whistles and are just as technology dependent as the rest of the world...
  10. stuartv

    stuartv Seeking the Light

    # of Dives: 200 - 499
    Location: Manassas, VA
    It seems to me that the trend of the last 100-ish years has been to refine and improve electronics so that things that were once regarded as way too unreliable to stake your life on become so reliable that people no longer think twice about using them. That trend seems to be embodied in modern eCCRs.
    TTPaws likes this.

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