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Fiona Sharp death in Bonaire

Discussion in 'Accidents and Incidents' started by JohnnyC, Oct 18, 2019.

  1. Dan

    Dan Orca

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    Thank you for such detail CCR dive plan to 300' depth. From @tursiops comments, below,

    It seems to me that diving down to 300' was not on her plan. Some unplanned thing happened that made her lose one of the AL40's and dove to 300'.

     
  2. PT4476

    PT4476 Nassau Grouper

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    If the reports regarding diluent and bailout are accurate I agree that it is unlikely that a 90m dive was her plan.
     
  3. Dan

    Dan Orca

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    It would be great to see the dive profile. How quickly she went to 300' and what was her bottom time at that depth.

    Is it possible to make a quick dip to 300' with such gear set up and survive to tell the tale?
     
  4. PT4476

    PT4476 Nassau Grouper

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    Possible, yes, but a very bad idea. No one I know with the training to to dives in the 300' range would consider it.
     
  5. Vicko

    Vicko Barracuda

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    Dilutent would be no more than 13% oxygen and no less than 50% Helium, most people would use something like 10/60 for dilutent.
    For bailouts we usually rent out 10/60 for bottom but people like their bottom bailouts to be Helium rich. You would definitely use a lot more than 2 40cf tanks. Something lie a full 12L steel at 250 bars bottom (12/50), 11L travel (20+/30) and 11L deco mix with o2 on the line, if no surface support than a 7l of O2 would be reasonable.
     
    Dan and PT4476 like this.
  6. Kay Dee

    Kay Dee Barracuda

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    For the experienced CCR diver, diluent gas mixes (and bailout for that matter) for that depth are a personal choice and not set in stone. While air is out of the question, ideally the partial pressure of oxygen in the diluent should not be more than 1.4 bar/ata (at max depth) and the narcotic effect of the nitrogen content to, again ideally, not be more than a 30m / 100ft equivalent air depth (at max depth). Of course, people do deviate from those diluent recommendations, generally by lowering them, i.e. being more conservative for both oxygen levels and narcosis effect. But some may even raise them.

    As someone else noted though, an experienced CCR diver on air (diluent) chasing a droped cylinder to 90m would / should be highly unlikely (but IMO not out of the realms of possibly happening). I have seen a CCR diver upon surfacing, then chase something much less valuable to almost 70m (and get bent for his trouble).
     
  7. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    Update

    Both 40s were on her. One was removed, dropped, recovered, by another member of the recovery team.
    The 40s contained 80% (untouched, still full) and 20/20, NOT air as previously reported second hand.
    Dil was air.
    Handset showed 91m.
     
    eleniel, Kmart921, Ayisha and 8 others like this.
  8. Wookie

    Wookie Secret Field Agent ScubaBoard Business Sponsor

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    It seems to me, not a rebreather diver, but been around plenty of them, that every bit of gas for this dive is completely inappropriate.

    Air dil
    40 cf 20/20 BO
    And 40 cf 80% for her offboard O2.

    She had made no provision if anything happened to her rebreather. She couldn’t use offboard gas to plug in in the event of a gas failure, and wasn’t carrying enough for bailout.

    Am I missing something?
     
  9. The Chairman

    The Chairman Chairman of the Board

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    Unfortunately, dives are often planned for everything to go well. Dive after dive reinforces the lie that this is an acceptable idea... until something goes horribly wrong. Hope for the best, but plan for the worst. The opposite is not always survivable.
     
  10. Kay Dee

    Kay Dee Barracuda

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    What are you missing? Not much.

    However, some CCR divers will run a hot bailout on the premise that should they have to bail at max depth they will bolt up to where the mix would be 1.6 ppO2 (or less). In this case that would be an ascent covering a vertical distance of 20 odd metres, which IMO would be a bit much (but in the 'comfort' zone as it were for some divers).

    Another thing to note is that some CCR divers only carry enough bailout to complete their deco up to (an event happening) about midway - or less - through their dive; working on the premise that if anything goes wrong with the 'breather then it will do so at the beginning or soon after on the dive (which is often the case).

    Not advocating either practice, just saying is all.

    It's the air dil that is truly worrying.

    The 'unknown known' it seems now is her time at max depth.
     
    Blueringocto_73 and Johnoly like this.

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