Hello and welcome to our community! Is this your first visit?
Register
Page 3 of 3 FirstFirst 123
Results 21 to 27 of 27

Thread: BSAC Nitrox 7

  1. #21
    Established TDF Member Tel's Avatar
    Join Date
    Dec 2012
    Posts
    3,446
    Likes (Given)
    238
    Likes (Received)
    1118
    Quote Originally Posted by 1st Ade View Post
    I've long hung up my Nitrox teaching fins but I remember a long and heated discussion with HQ on this topic: -

    Me "So an OD can dive up to 36%, right"

    HQ "No, they can dive 32% or 36% but not any other mix"

    Me "So if they dive 36% in the morning then are offered an 'air top' they can't accept it"?

    HQ "No, they have the option of draining the tank right down or can get someone to do the maths to give them 32%"

    Me "So you'd rather they dive 21% (on air tables) than, say 30% (on air tables)"?

    HQ "Them's the rules"

    This was a concession given to extremely inexperienced divers who could have a really bad day if it all went wrong.
    That concession was necessarily at the mercy of a strict control to ensure at this level their were no variants.

    A second dive could have been done on air, on Nitrox if prepared to wait for a mix or take a second spare cylinder
    as common on most UK boats with NX ready to go.

    In a few cases it might have been about time to get a mix, but in the main it was entirely about cost and
    in this enviroment not sure that's a good enough reason.

    I can understand where you are coming from with an individuals POV, with (hopefully) a tight control of QA.
    but an agency (BSAC) doesn't have that luxury. if the vast majority won't be on Nx anyway, other controis
    such as another cylinder ready to go (common) and plenty of time to get a proper mix between dives. All that's
    left is a very small number that would want a top-up. Seeing as newbies drain cylinders a top on what's left
    won't get that high a mix. So it's either an open season & wooly standard for a VERY small number of divers
    vs a solid one for all.

    At the time they went with the latter and at the time they were right

  2. #22
    Established TDF Member
    Join Date
    Dec 2012
    Location
    Milton Keynes
    Posts
    905
    Likes (Given)
    165
    Likes (Received)
    356
    Quote Originally Posted by Tel View Post
    This was a concession given to extremely inexperienced divers who could have a really bad day if it all went wrong.
    That concession was necessarily at the mercy of a strict control to ensure at this level their were no variants.

    A second dive could have been done on air, on Nitrox if prepared to wait for a mix or take a second spare cylinder
    as common on most UK boats with NX ready to go.

    In a few cases it might have been about time to get a mix, but in the main it was entirely about cost and
    in this enviroment not sure that's a good enough reason.

    I can understand where you are coming from with an individuals POV, with (hopefully) a tight control of QA.
    but an agency (BSAC) doesn't have that luxury. if the vast majority won't be on Nx anyway, other controis
    such as another cylinder ready to go (common) and plenty of time to get a proper mix between dives. All that's
    left is a very small number that would want a top-up. Seeing as newbies drain cylinders a top on what's left
    won't get that high a mix. So it's either an open season & wooly standard for a VERY small number of divers
    vs a solid one for all.

    At the time they went with the latter and at the time they were right
    Bollox Tell they screwed up and as every thing had been printed that become the rules. I was told they knew it was wrong by an ex NDO

    Graham.

  3. #23
    Established TDF Member Tel's Avatar
    Join Date
    Dec 2012
    Posts
    3,446
    Likes (Given)
    238
    Likes (Received)
    1118
    Quote Originally Posted by bottle maker View Post
    Bollox Tell they screwed up and as every thing had been printed that become the rules. I was told they knew it was wrong by an ex NDO

    Graham.
    Who are "they"?

    The authors, the control group the Instructors/NDO etc, etc?
    Just cause one group of BSAC think another part of BSAC has screwed up, doesn't mean that the other part is actually wrong.
    Comes down to personal opinion, NDO's have never fallen out and badmouthed authors ever

    Besides BSAC have never been shy at punting out an email correction etc. so find it VERY weak that an NDO would struggle
    with that one, that is unless he was voted down by those that DID think the authors were right, as do i (still)

  4. #24
    TDF Member
    Join Date
    Jan 2013
    Location
    South Midlands
    Posts
    142
    Likes (Given)
    115
    Likes (Received)
    118
    Quote Originally Posted by Tel View Post
    This was a concession given to extremely inexperienced divers who could have a really bad day if it all went wrong.
    That concession was necessarily at the mercy of a strict control to ensure at this level their were no variants.

    A second dive could have been done on air, on Nitrox if prepared to wait for a mix or take a second spare cylinder
    as common on most UK boats with NX ready to go.

    In a few cases it might have been about time to get a mix, but in the main it was entirely about cost and
    in this enviroment not sure that's a good enough reason.

    I can understand where you are coming from with an individuals POV, with (hopefully) a tight control of QA.
    but an agency (BSAC) doesn't have that luxury. if the vast majority won't be on Nx anyway, other controis
    such as another cylinder ready to go (common) and plenty of time to get a proper mix between dives. All that's
    left is a very small number that would want a top-up. Seeing as newbies drain cylinders a top on what's left
    won't get that high a mix. So it's either an open season & wooly standard for a VERY small number of divers
    vs a solid one for all.

    At the time they went with the latter and at the time they were right
    This (for me and after 30+ years diving under BSAC, and only under BSAC) was where i started to lose interest in HQ

    I can think of no (none, zero) circumstances under which an OD would be safer diving a guaranteed 21% mix than a "32%ish" mix. DCI - the mix is safer. Narcosis - The mix is safer. O2 Toxicity - If the OD gets an O2 hit on the mix at the depth they are qualified they have way more issues than the mix. Donate to another diver - at the depth they should be at, it's Safe Air [TM] yes?

    And it went totally against the grain of the First Class Diver exam of "the aim is to go diving, safely"

  5. #25
    Established TDF Member Tel's Avatar
    Join Date
    Dec 2012
    Posts
    3,446
    Likes (Given)
    238
    Likes (Received)
    1118
    Quote Originally Posted by 1st Ade View Post
    This (for me and after 30+ years diving under BSAC, and only under BSAC) was where i started to lose interest in HQ

    I can think of no (none, zero) circumstances under which an OD would be safer diving a guaranteed 21% mix than a "32%ish" mix. DCI - the mix is safer. Narcosis - The mix is safer. O2 Toxicity - If the OD gets an O2 hit on the mix at the depth they are qualified they have way more issues than the mix. Donate to another diver - at the depth they should be at, it's Safe Air [TM] yes?

    And it went totally against the grain of the First Class Diver exam of "the aim is to go diving, safely"

    If a bastard Nx mix lower than the standard 32% is better/safer than air, it must be true that the actual standard of 32% is better/safer still.

    This discussion has nowt to do with the gas at all, it's soley down to logistics.

  6. #26
    TDF Member
    Join Date
    Jan 2013
    Location
    South Midlands
    Posts
    142
    Likes (Given)
    115
    Likes (Received)
    118
    Quote Originally Posted by Tel View Post
    If a bastard Nx mix lower than the standard 32% is better/safer than air, it must be true that the actual standard of 32% is better/safer still.

    This discussion has nowt to do with the gas at all, it's soley down to logistics.
    Tel

    On the money.

    But the exam question was "given a choice of air or an unknown* mix less than 36%". In an ideal world go for the highest mix allowed by EAD. In a non ideal world go for the next lowest mix available. Unless your an OD...

    [ * - for "unknown" read a known figure (I wouldn't let anyone dive without someone measuring the mix) but one that is not an integer ending in "2" or "6" between 29 and 39 ]

  7. #27
    Established TDF Member
    Join Date
    Jan 2013
    Location
    South of France
    Posts
    525
    Likes (Given)
    116
    Likes (Received)
    137
    Quote Originally Posted by Tel View Post
    If a bastard Nx mix lower than the standard 32% is better/safer than air, it must be true that the actual standard of 32% is better/safer still.
    Clearly, the less nitrogen the better, but since the gas is being treated as the worst case (air) anyway, it doesn't seem to make any difference (within the bounds of the MOD) how much there actually is.

    That being said, describing that approach as "nitrox training" seems a little generous.
    Last edited by shapeshifter; 30-11-2019 at 11:45 AM.


 
Page 3 of 3 FirstFirst 123

Posting Permissions

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