• Welcome to ScubaBoard

  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Caves and transmitters.

Discussion in 'Cave Diving' started by blac86, Jul 17, 2017.

  1. karstdvr

    karstdvr Solo Diver

    # of Dives:
    Location: South GA
    1,852
    621
    113
    Not to be argumentative, but this is a okay measure if you are not stressed. Frequently, problems in cave diving multiply and snowball, and stress becomes a huge factor, and things like this aren't noticed. I have seen some crazy things in incidents and accidents, and when you detail the situation and the amount of stress, then it is understood.

    This is the assumption the transmitter fails, but the receivers are not infallible. I love my Shearwater and think they make highly reliable equipment and quality equipment. But I have mine go "tits up" a couple times in the cave, by my error with a battery that was dying, or some other unknown reason. I had a back up computer of another manufacturer, so no problem, which follows your two primary light analogy.

    I am not anti-technology,but diving in the overhead, be it recreational or exploratory deserves equipment that has been well tested by a large population, and highly reliable. The analog spg has a highly reliable history in the overhead, and don't recall an accident due to a failed spg. But, wireless spgs need conservative dive profiles and X number of hours of bottom time to show a reliable history.
     
  2. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,681
    7,007
    113
    @karstdvr so kelly, assuming we aren't on a mission type dive that has to be complete and can't be turned, why not just turn the dive and come home?

    on the stress thing, again. You forget to switch tanks because things went tits up, so you breathe it and it gets hard to breathe because it's empty. Switch to the other tank. How is that any different than coming home on backmounted doubles when you had to shut the left post off and have no idea what you're coming home with? You have either enough gas and you make it, or you don't have enough, and don't.
     
    RyanT likes this.
  3. karstdvr

    karstdvr Solo Diver

    # of Dives:
    Location: South GA
    1,852
    621
    113
    Just replying to the comment that was made about noticing buoyancy shift in sidemount tanks, mutually exclusive to backmount. In a CTJ moment or some other stressful moment, buoyancy shift will probably not be noticed. As Jim Wyatt eluded to this, this can increase the stress of the moment as well. Hypothetically, read Andrew Ainsle's long write up about a dive that went bad, with CO2 build up, missing his line etc, and add failed digital spg-do you think in that write up he would have said, I noticed a change in buoyancy in my sidemount tanks.
     
  4. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,681
    7,007
    113
    i'd be shocked if he did, but the point still stands that you either have enough to get out or you don't, so I think you can only argue so much on if it would create that much more of a problem. That said, I have had some interesting situations that have caused dives to get turned and on those, and even on normal dives, I don't check my SPG's on the way out. With my DPV gas planning strategy, I switch to my other stage when I take a breath and my jetstream freeflows a bit after I stop inhaling. This tells me that I'm at 200psi and it's time to switch bottles. No need to look. My buddy has a similar strategy on "normal" second stages and when he notices WoB getting different, it's time to change to the next bottle. I'd use the same in an emergency exit on backgas
     
  5. HDWEB

    HDWEB Garibaldi

    # of Dives: 100 - 199
    Location: Mexico
    2
    0
    1
    do they make a Y or Tee that i could mount my transmitter and have a back up spg
     
  6. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: U.S. East Coast
    7,790
    5,453
    113
    Your first stage undoubtedly has two HP ports. No Y/Tee needed.
     
  7. RyanT

    RyanT Solo Diver

    # of Dives: 500 - 999
    Location: Maryland
    1,745
    1,369
    113
    Similarly, I use button gauges on my deco bottles (OW dives). They're great for confirming full bottles before the start of the dive. Beyond that, I rely on my gas planning, no need to monitor the pressure in those bottles during a dive.
     
    Paul1852 likes this.
  8. halocline

    halocline Solo Diver

    8,469
    2,574
    113
    A few of my buddies in MX are using the perdix AI in caves all the time these days. These are very experienced instructors/explorers. They feel that the new shearwater transmitters are more reliable than SPGs, and it would not surprise me if this proves to be true in time. SPGs do fail, those spool o-rings blow occasionally (although typically upon pressurization, not mid-dive).

    I'm cheap and I already have an SPG and a non-ai computer, so it's not for me, but bet as time goes on more and more cave divers will be using AI.
     
    HDWEB likes this.
  9. Superlyte27

    Superlyte27 Cave Instructor

    # of Dives: 5,000 - ∞
    Location: Florida
    3,602
    2,600
    113
    I use a Perdix AI in caves when I'm on CCR. It plugs into my oxygen and Dil. So far, I haven't had a single connection issue.
     
    HDWEB likes this.
  10. Rechno

    Rechno Nassau Grouper

    # of Dives: 200 - 499
    Location: Germany
    137
    109
    43
    But does not the same logic apply for SPG? Since it can fail as well (ok, so far my onl SPG failure was during an OW vacation dive) you would need redundancy there as well.
    I´m definitely with you, in that it makes sense and if i had transmitters I would probaly also use an SPG as back-up, however I do not see this as a MUST.

    I had several discussions with divers that are totally against transmitters (without back-up). They always state "if it fails you dont know how much gas you got left!" but at the same time they only dive one SPG.
    Personally I say, that my "back-up" is the prio gas planning. So if transpitter or SPG fails I turn the dive and know that I got enough gas left.
     
    HDWEB likes this.

Share This Page