+ Reply to Thread
Results 1 to 7 of 7

Thread: Rebreather and OC computers overlap

  1. #1
    RBW Member g3cko is an unknown quantity at this point g3cko's Avatar
    Join Date
    Oct 2015
    Location
    Southern California
    Posts
    7
    looking

    Rebreather and OC computers overlap

    Hi all,

    I think I may know the answer to this, but.... just in case. I am currently OC, but longer term (maybe this year) I absolutely want to take a CCR course and (I'm assuming, very likely) continue diving CCR/buy my own unit.

    Cost is definitely something I'm conscious of (underwater photographer), so I was thinking, "it would be really cool if I could dive the same computer OC and CCR" and additionally, it didn't make a ton of sense to me (in the future) to have a Shearwater stand alone for OC and a hardwired for CCR.

    Is the only option for "reuse" here to go mCCR to reuse the same computer OC/CCR? As I understand, the Shearwater computers that are controllers are hardwired for reliability sake, and are also customized per rebreather? I am currently looking at the rEvo if that changes anything.

    In my hypothetical future, if I do get a CCR I imagine I would still dive OC some for photography, as I solo dive often, and my gut feeling/lack of experience tells me this is less safe on CCR.

    Thanks!
    -Aaron

  2. #2
    SBOD Pilot Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish's Avatar
    Join Date
    Jun 2013
    Location
    Perth, Western Australia
    Posts
    836
    AP Classic SBOD v. AV1c

    Re: Rebreather and OC computers overlap

    There are various types of computers along the scale, and these can be kinda categorised:
    1. Pure recreational. Air only, very little tweakability, deco handling is mostly an emergency backstop rather than an intended use. Couple hundred bucks.
    2. Nitrox/fancy recreational. As above but add nitrox capability. These often have extra features like wireless tank monitors and compasses and so on. Significantly more expensive. Most of the computers on the market fall into this category.
    3. Mixed gas/tec computers - multiple gasses, handle deco like they mean it. Things like the Suunto Helo2, some of the Liquivisions etc.
    4. As above but with PPO2 setpoint control. Good backup for your CCR diving or a fine computer if all your unit has on board is PPO2 management. Petrel, Perdix, OSTC(?), AV1 etc.
    5. As above but with PPO2 measuring from one or three sensors via cable connection. Petrel EXT, AV1-F, NERD etc.
    6. As above but with solenoid control. AV1c etc.

    If you have a nitrox computer and you're not planning dives using mix for a while, you can do some calculations based on your planned depth and come up with a nitrox mix that's the equivalent of most of your dive. So you can get by with that.

    If you buy a Petrel or Perdix with no cell input, you can still set the setpoint to match what the controller is doing and you have a backup for deco, ndl, ascent rate, deco stops etc which will be pretty close to the primary.

    If you buy a Petrel EXT with a cell input and wire the cable into your mCCR, you can disconnect it and pop the end cap in and dive it OC.

    Generally, the controller computer is hard wired into the breather so that's not an option for OC.

    Two options leap out at me:
    1. Buy a standalone computer that supports setpoint. A nice shiny Perdix or Petrel 2 or AV1 or similar. There's a million to choose from these days. You have something portable and easy for OC which will also track your dive quite happily when you're on the unit. You don't /really/ need it wired into your breather to do the job. It's a backup deco computer. On a rEvo you have the primary Petrel plus one or two Dreams to monitor the PPO2, there's no need to add more.

    2. What's this "sometimes OC" malarky you're talking? You may well find (it's certainly what happened to me) that, once you start your MOD1, you never dive OC again. Your reg set for OC gets converted into bailout regs. Your trip planning starts hinging on breather support. You think nothing of rigging your unit for a 6m dive.
    Last edited by Captain Starfish; 20th February 2016 at 00:03.

  3. #3
    RBW Member g3cko is an unknown quantity at this point g3cko's Avatar
    Join Date
    Oct 2015
    Location
    Southern California
    Posts
    7
    looking

    Re: Rebreather and OC computers overlap

    Appreciate the detailed response!

    I realized I didn't really give any background, my current state of computers is a bit mixed. I have a wrist mount Suunto Zoop (good deal on it) for diving nitrox which I end up using for travel, and an old Suunto Eon (the old one) for my "normal" local shore diving, with the integrated compass, air, etc (but no nitrox support).

    I guess I'm interested in combining the two, so I get full nitrox support, as well as the compass and the readability/backlighting and support for deco/mixed gas/etc should I continue down that path.

    Since I've had my eye on CCR, I was curious if I could get a step closer upgrading ($1k off cost to get CCR) without sacrificing. From a "not in the loop" perspective, I don't see why set point control can't be done over a fischer (removable) connection but I'm new to this all.


    2. What's this "sometimes OC" malarky you're talking? You may well find (it's certainly what happened to me) that, once you start your MOD1, you never dive OC again. Your reg set for OC gets converted into bailout regs. Your trip planning starts hinging on breather support. You think nothing of rigging your unit for a 6m dive.
    Haha! A good portion of my current motivation is actually coming from the photography side, not to say that can't change down the road. Longer bottom time + no bubbles.. more chances of "the shot"

    Again, thanks for the reply
    Last edited by g3cko; 20th February 2016 at 01:23.

  4. #4
    SBOD Pilot Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish's Avatar
    Join Date
    Jun 2013
    Location
    Perth, Western Australia
    Posts
    836
    AP Classic SBOD v. AV1c

    Re: Rebreather and OC computers overlap

    The thinking behind the controllers being hard wired is pretty simple. Fischer connecters, as fabulous and convenient as they may be, are a well known failure point. Particularly when a cable plugs into a bulkhead connector. They snap, they leak, they futz out.

    If it's for a backup monitor, it's annoying but not the end of the world. If it's for a controller, and you snag the cable and break the connector, your rig has just become a toxic unknown.

    I know of at least one guy who's taken the manufacturer advice from AV-UWT into consideration and decided the risk's worth it, so AV-UWT made him an AV1c controller with a fischer connector. The mad russian is happy to let his customers take the responsibility for their decisions unlike most western manufacturers who tend to be quite litigation shy and mandate end-use decisions for we sheeple. Not their fault, it's a function of the society we've created for ourselves.

    I bang on about how good these AV1s are on a lot of threads but they're a nice unit and the manufacturer is a lot more responsive to unconventional customer requests than, say, Shearwater and the like. Might be worth a look.

    Still. If you're looking down the barrel of a rEvo or other rebreather that comes equipped with a computer and controller anyway, there's not a lot of point in getting another one now - you can't run both at once because it screws up their PID loops and they just get confused.

    I'd get something that can handle a setpoint and has the other toys you want. Something like the plain AV1, Perdix, maybe a T1 or H1, or one of a plethora of computers coming out with setpoint support these days. All have pros and cons, do your research :)

  5. #5
    Hammermeg, Copis2, Kiss divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe is just really nice divingabe's Avatar
    Join Date
    Oct 2005
    Location
    Lake City,FL
    Posts
    654
    Meg 2.7, Hammermeg, copis meg

    Kiss Sport, Draeger dolphin

    Re: Rebreather and OC computers overlap

    To answer your question.
    Get a Petrel 2, it does all you need and want, compass, oc, nitrox, trimix, ppo.
    With this you are covered.
    When you do get a ccr you will want to use a backup computer for safety, and the petrel will fit the need.
    If you do get a ccr and it does not have integrated deco your petrel will be your primary and you will be looking for a backup (bottom timer plus tables) or equivalent.
    A stand alone computer works quite well as a primary deco monitor.
    From my personal experience diving ccr with integrated deco and a stand alone computer the deco calculations and obligations between the two units never varied more than a minute or so.
    Gabe

  6. #6
    Fake Diver Jeff Pack will become famous soon enough Jeff Pack will become famous soon enough Jeff Pack will become famous soon enough Jeff Pack will become famous soon enough Jeff Pack's Avatar
    Join Date
    May 2012
    Location
    USA
    Posts
    836
    Meg

    KISS

    Re: Rebreather and OC computers overlap

    Quote Originally Posted by divingabe  View Original Post
    From my personal experience diving ccr with integrated deco and a stand alone computer the deco calculations and obligations between the two units never varied more than a minute or so.
    Gabe
    My buddys meg is integrated, I run standalone. We are usually less than 2 minutes apart.

  7. #7
    RBW Member g3cko is an unknown quantity at this point g3cko's Avatar
    Join Date
    Oct 2015
    Location
    Southern California
    Posts
    7
    looking

    Re: Rebreather and OC computers overlap

    Thanks for the further info here! I'll check out the AV1 - I've actually not heard of that one.

+ Reply to Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts