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Why extra air when solo?

Discussion in 'Solo Divers' started by pauldw, Jul 11, 2019.

  1. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
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    Debris clogging the valve is quite common. It happened to my son. We were at the Miramare Marine Reserve in Trieste, Italy, making underwater acoustics experiments at very shallow depth (6 meters, less than 20 feet). In 2009.
    I was at surface snorkeling and keeping care of the cables running form the hydrophone array to the jetty. My son had a single 15-liters back-mounted bottle, and given the minimal depth we did not take care of mounting the second regulator on the bottle (in Italy the usage of an octopus is not recommended, as most diving centers provide bottles with dual valve, hence a complete set of two first stages and two second stages is the standard equipment here).
    At a certain point my son did show me that the regulator was having problems, he removed it by his mouth and did show me that, even pressing the front button, just a small line of air bubbles was coming out.
    The bottle was fully charged a few minutes before, so of course there was air inside.
    The air flow form the regulator was really minimal, but sucking as hell my son managed to place properly the hydrophone probe on the sand, and then he surfaced. We climbed on the jetty and inspected the equipment, finding that the metal filter at the entrance of the regulator was full of debris. Mostly rust and grease. Those things happens, particularly when you rent bottles instead of using your ones...
    Hence the lesson is clear. For solo diving:
    1) Never use an octopus, you need two separate valves and two separate first stages.
    2) Better to use a twin-bottle system, so the air reservoirs are truly independent, but can be made communicant if needed by opening the manifold between them.
    I am not in favour of an additional side-mounted pony tank, it adds a lot of drag, and can be tangled easily (there are a lot of fishing lines and nets here around). Better a pair of properly sized back-mounted twins. For modest depths (the only ones that I even consider safe for solo diving) two 7-liters or 8-liters are fine, smaller and lighter than a single 15-liters, and more streamlined. Of course you need two pressure gauges, and a regulator with a left-side tube or a very long tube. You use half of the initial pressure on one bottle, then you change regulator, use half from the second bottle, and then you are done, time to resurface.
     
  2. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
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    Diving 70 feet, solo without any redundant air supply is against all training "standards" or recommendations, isn't it?

    • Why should individual divers "respect" your choice if it is inconsistent with current training?
    • Should divers respect all divergences from training standards, or only a select few?
    • Does the frequency of a particular diver's non-compliance with training standards provide validation of the practice and garner respect for it?
    Perhaps I am incorrect and there are training agencies that support diving past 60 feet, while solo, with no redundancy?
     
    markmud likes this.
  3. markmud

    markmud Self Reliant Diver--On All Dives. ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: South Lebanon, Ohio
    1,185
    1,151
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    Hi johndiver999,

    You have a really good point. I have argued similarly on other threads where divers were validating practices that are against acceptable norms (tech divers diving to almost 200 fsw while on a single tank; "it's OK, we do it all the time!").

    How do we combat this; engage the scuba police? It's her life right?

    You have proved a dichotomy of thought!

    cheers,
    m
     
  4. jeffsky29

    jeffsky29 Nassau Grouper

    # of Dives: 100 - 199
    Location: Delray Beach, Florida
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    Wow, 15 pages: Why extra air when solo?

    I think the best answer to this question is “
    Why not?”
     
    FreeFlyFreak and markmud like this.
  5. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
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    I propose to read back the original post which initiated this thread.
    The question was why a pony tank is usually considered a standard equipment for solo diving.
    After accepting that in the end everyone is free to endanger his life at will, as a diving instructor I feel obliged to provide my expertise and knowledge for answering.
    And my answer is as follows:
    1) A pony tank, either side-mounted or back-mounted, is a piece of gear usually employed only for technical diving, in caverns or inside wrecks. I do not recommend a pony tank for free-water diving at recreational depth (30m max) and well withing NDL limits, which in my opinion is the only case where solo diving is meaningful.
    2) Instead I always recommend two complete regulators on two independent valves (this also for buddy diving). No octopus. An octopus is handy just for the dive master, so he can have TWO additional second stages for others, beyond her/his primary.
    3) For solo diving, it is highly recommended that the two independent regulators are fitted onto two independent bottles of equal size, either side mounted, or, better, back mounted with an openable manifold connecting them.
    4) You can switch back to a single bottle (but always with two valves and two fully independent regulators) only when the depth is so shallow and the diving profile is so modest and there is absolutely no risk of entanglement that you can safely resurface in a few seconds without any risk. Let's say 10m maximum, on flat sand.
    5) These are my suggestions, but are not sculpted in stone, and I accept that people take their own risks not following these recommendations.
    6) And I do not pretend that I know all the truth, I am here mostly for learning, not for teaching, hence I am ready to change my opinion if reasonable proof is given that my previous believing are wrong.
     
    RayfromTX likes this.
  6. markmud

    markmud Self Reliant Diver--On All Dives. ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: South Lebanon, Ohio
    1,185
    1,151
    113
    Hi jeffsky29,

    You should be awarded the gold star for this thread. The most profound and shortest answer to the OP's question. Slinging or tank mounting a pony bottle is painless.

    cheers,
    m
     
    jeffsky29 likes this.
  7. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
    909
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    I am just asking questions. I think it is an interesting topic. I understand that she willingly accepts the potential consequences of her decisions. I would not propose to police how people dive off of their own boats.
     
    Bob DBF and markmud like this.
  8. pauldw

    pauldw Solo Diver

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    If that were true, wouldn't everyone be doing it? Doesn't the fact that not everyone is doing it show that you're overlooking something?
     
    markmud likes this.
  9. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
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    So, when training, the proper standards should be used by instructors. Recommendations are just that, if the students choose to ignore them, it says more about the instructors teaching skill than anything else.

    If one is an instructor, then the points made might be important, however as long as DMs take OW divers below 60', or AOW below100', having no repercussions from their agency, why should anyone else care about training standards or recommendations outside of class? There is no SCUBA law, it is a group of Agency and industry rules that may, or may not, be in agreement.

    And some agencies reccomend that no solo diving should ever be done, so each diver will have to decide what is right for them, as the agencies can't agree on standards and recommendations.


    My solo diving predates any agency training by at least 40 years, if I needed the ticket I would get it, but... I could comply with the course while taking it, however I doubt if I would change my solo diving after the fact, except where required and enforced.
    The difference in training I have seen over the years is the change from developing good judgement in a diver, to training by rules. The problem with rules is that once one sees the rule is a matter of choice, one needs good judgement to replace it with one's own. Without good judgement, one could just dive the Blue Hole in Belize on an OW ticket with a PADI five star. To be honest they say they would prefer AOW, but it's not mandatory.


    Bob
     
  10. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
    909
    814
    93
    I guess your one point is that: when some "professional" divers fail to follow all standards while being "professionally engaged" this action serves to invalidate the recreational diving guidance provided by an agency? That is something I had not previously considered.

    I'm not attempting to denigrate Ana for diving how she wants, but the request for "respect" for the activity opens up a pretty wide avenue of discussion.
     
    Bob DBF and markmud like this.

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