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Thread: Deep Stops

  1. #131
    Old but keen Mark Chase's Avatar
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    Quote Originally Posted by gobfish1 View Post
    your average suunto diver would need 3 spots showing on his ascent graph to get between 8 and 10m per min
    and most would slow it down if one popped up ,

    by the way im not having ago at you or other divers that posted GF,s used ,
    we all sit at home playing with the pc tables , but none of us are diving them ,

    TTS , your only looking at tts to stay with in your planned run time and bail out capabilities,
    if you manipulate the set point on ascent tts could look nothing like it was as you left the wreck / start of ascent ,

    unless divers add more info about how they dive the new GF,,s no one is going to get a feel for what numbers to run with,

    if someone post,s they use 45/75 but wont post that he pad,s the last stop by 10 mins and his slow on his ascent
    the numbers are useless as that,s not what his diving ,
    interesting thread all the same ,

    In that vein

    Back in the deep stop days I was gas diving with a group who had total control over the boat and we usualy ran 3 hours sometimes 4 so 45mins at 70m was a typical dive profile for me. I tended to run what ever profile ended up with a 3 hour run time.


    Since switching to fewer and now no deep stops my diving has changed considerably due to the max two hour restriction imposed on most boats thease days

    Also theres not so many easy access deep dives, I don't have any great need to go deep all the time and bang for buck shallower is better on a 2 hour max runtime. So the shift in my diveing has gone from 60-80m mainly to 40-60m mainly and fewer of them

    So by the time I got to 80/80GF I was firmly in the latter camp.

    Would I run 80/80 on a 100m dive?

    Probably not. but I'd be more inclined to run 70/70 rather than 50/80

    Profile wise. 1.3 set point 20m END max and last 20mins of any profile on pure 02 CCR and stay on o2 to surface / ladder and for 5mins after sitting down on the boat (longer if getting on the boat was a struggle)



    HTH


    Chasey

  2. #132
    "Three Sheds" Janos's Avatar
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    Quote Originally Posted by gobfish1 View Post
    your average suunto diver would need 3 spots showing on his ascent graph to get between 8 and 10m per min
    and most would slow it down if one popped up ,

    by the way im not having ago at you or other divers that posted GF,s used ,
    we all sit at home playing with the pc tables , but none of us are diving them ,

    TTS , your only looking at tts to stay with in your planned run time and bail out capabilities,
    if you manipulate the set point on ascent tts could look nothing like it was as you left the wreck / start of ascent ,

    unless divers add more info about how they dive the new GF,,s no one is going to get a feel for what numbers to run with,

    if someone post,s they use 45/75 but wont post that he pad,s the last stop by 10 mins and his slow on his ascent
    the numbers are useless as that,s not what he,s diving ,
    interesting thread all the same ,
    You're spot on Gobbers.

    Personally when I used a trapeze a lot I used to rocket up the shot at 12m/min to my first stop, Suunto beeping like crazy. I still go quickly now that more of my deep diving is coming up under a blob, it's still around 9 or 10m/min. The Suunto still beeps a bit. but not as much That said the difference is only a couple of minutes, but then a couple of minutes bottom time is five minutes deco, hmmm.

    For the last stop, I tend to run 1.4ish at 9m and 6m, then when the shearwater shows a 3m stop, I run pure O2 and go to 5m or 4m. This makes no difference to the deco, but it does reduce the CNS.

    Janos
    You can lead a horse to water but you can't climb a ladder with a large bell in both hands - Vic Reeves
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  3. #133
    Last of the Mohicans gobfish1's Avatar
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    Its interesting to me that you both use o2 at the end of your deco time,s and not right off the bat as soon as your at 6m
    ie when your off gassing the most , putting the cns clock to one side , why do it later on , what s your thinking on that ,

    lets keep it at around
    180min run times max
    Last edited by gobfish1; 01-12-2017 at 05:31 PM.

  4. #134
    "Three Sheds" Janos's Avatar
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    Quote Originally Posted by gobfish1 View Post
    Its interesting to me that you both use o2 at the end of your deco time,s and not right off the bat as soon as your at 6m
    ie when your off gassing the most , putting the cns clock to one side , why do it later on , what s your thinking on that ,

    lets keep it at around
    180min run times max
    TBH I often do run pure o2 on the 6m stop. When I first get there I find it bounces around a bit (off gassing?) but once things have settled down a bit then Iíll boost it up a bit. I suppose if the dive is going to plan then Iím not too anal about it dropping a bit. It will normally be somewhere between 1.4 and 1.5 I suppose.

    Iím also happy boosting it up on one of the deeper stops (Mccr). So I might get to 18m, notice ppo2 is a bit low, and welly it up to 1.6 and then let it drop back down as I ascend to 15 and 12.

    The last bit of deco is always pure o2 though.

    Janos

    PS - most of my deep diving these days is in the 60m range. Anything below 80m is A Big Dive for me.
    You can lead a horse to water but you can't climb a ladder with a large bell in both hands - Vic Reeves
    Hellfins - a friendly London dive club
    My music video: Dive the UK, cos that's the way it is. Huh!

  5. #135
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    Quote Originally Posted by Mark Chase View Post
    Profile wise. 1.3 set point 20m END max and last 20mins of any profile on pure 02 CCR and stay on o2 to surface / ladder and for 5mins after sitting down on the boat (longer if getting on the boat was a struggle)
    Interesting - I always spend first part of long stops at high PO2 - but since I never spend more than 20min at 3m its usually case that I arrive surface close to 1.0. At 6m this means I stay as close to 1.6 as possible at 6m for 15mins and after that don't bother what the PO2 is - I have let it run down to 0.7 for large majority (over 60mins) of 6m stop and never felt any worse upon surfacing. I think we spend way to long on last stop chasing an unrealistic asymptote.

  6. #136
    Old but keen Mark Chase's Avatar
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    Quote Originally Posted by gobfish1 View Post
    Its interesting to me that you both use o2 at the end of your deco time,s and not right off the bat as soon as your at 6m
    ie when your off gassing the most , putting the cns clock to one side , why do it later on , what s your thinking on that ,

    lets keep it at around
    180min run times max

    You can reely crank up the CNS after an hour and a half on 1.3 and another hour and a half on 02. I am of course a total dive god but I still don't fancy my chances with 02 Tox


    That and I find I get all phlemey and chesty after too much 02


    WHat I like about High PP02 last is:

    1: If it all goes a bit weird (collapsing vision etc) I can pop up on 02 with the minimum risk where as if that happens early on in deco I could have quite a commitment left and that would encourage me against my calm sitting by the PC judgment to stay down thus risking a far bigger problem. I find my already chlanged IQ drops off quite a bit once immersed in water.


    Also at the end of the dive on pure 02 you notice when you stop off gassing Helium & Nitrogen as the 1.6 becomes more stable. Mentaly I am thinking I am pretty clear on deco commitment at that point.
    Last edited by Mark Chase; 02-12-2017 at 09:31 AM.

  7. #137
    Old but keen Mark Chase's Avatar
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    Quote Originally Posted by graham_hk View Post
    Interesting - I always spend first part of long stops at high PO2 - but since I never spend more than 20min at 3m its usually case that I arrive surface close to 1.0. At 6m this means I stay as close to 1.6 as possible at 6m for 15mins and after that don't bother what the PO2 is - I have let it run down to 0.7 for large majority (over 60mins) of 6m stop and never felt any worse upon surfacing. I think we spend way to long on last stop chasing an unrealistic asymptote.
    If I can do 3m Ill do longer on 02 but often its a bit rough doing 3m on a deco station and theres only two lines up from the 6m trapize so you can get a bit crowded and in peoples way as they want to ascend.

    SO often do all final stops at 6m out of necessity.

  8. #138
    Last of the Mohicans gobfish1's Avatar
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    Up to about 80m on a 3h dive i finish my 9m stop around 100/120 mins 60 odd cns ,
    6m stop is round 60 mins
    i do the first 30mins at 6m puts me at say 120 cns the last 30 i split in two 15mins at 5m and last 15mins above 5m
    its not often i finish a dive with more than 150 ish on clock , ( id need deeper than 80m or longer run time )
    most dives its 120/130 ish ,
    think i avg 1.5po2 over the last hr , so lest,s call it 50cns plus the 65 cns i have from the bottom time and back to 6m

    ps
    i also get a bit chesty but only on two dives a day over a week , about a J,s worth
    be4 its time to rest my lungs ,

    i blame the Helium

    Gf,s i use ,
    what ever my buddy is using lol
    Last edited by gobfish1; 04-12-2017 at 03:25 PM.

  9. #139
    TDF Member Clare's Avatar
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    Zombie thread (almost) but fancied making a quick contribution.

    The 20/85 GF settings were standard teaching when I did my first tech training in 2004/5 so its far from a new recommendation. There were one or two of us who dived 10/120 or suchlike - but not many, our more conservative buddies tended to object and it was never mainstream teaching as far as I know. Ratio deco, which has not been taught for a very long time, equated at about 20/85. There's been a bit of fudging with the maths on this thread - 80 per cent of 8 ATAs is not and never will be 65 meters - but even in the hey day of deep stops few (with a couple of notable exceptions) argued that the stops at 80 per cent should be any more than a pause to control/change ascent rate from the maximum.

    Ascent rates are, I believe, also fundamental to the debate. I remember talking to Dr DD about this and his assertion that he would ascend at 20 mph if he could (there was quite an emphasis on if ) until his first stop.

    There was a time when some divers in the UK were questioning both deep stops and also whether an ascent rate of 9 or 12 meters per minute could be achieved deep over a distance - without lose of control which would mean missed stops further up. On this thread there are divers which suggest that they have never managed a fast ascent deep. I took many technical divers on a training fast ascent and they either could not keep up or admitted to being very concerned whether or not they would be able to stop.

    When Al and I did our CCR conversion course with Richie we bailed out as planned at 30 odd meters and moved at pace to our first stop which, on recollection, was 15 meters. Richie saw us move so fast he thought we'd lost control - until he saw us stop at the required depth. His comment at the time was "people always plan to move at that rate but never do - I just figured the two of you would be embarrassed ). It does take practice and it can be a little disconcerting all that bubbling and popping etc. On CCR you are even busier but it is still manageable.

    I repeatedly, whilst teaching, emphasised that if you have planned your dive and planned your ascent then moving slower than planned or staying over at stops was not making your dive more conservative - quite the opposite. Obviously using a computer means that the brain on your wrist will compensate for any delay on ascent and change the plan accordingly but those who like to plan their dives should set realistic ascent rates. It helps plan bail out accurately too.

  10. #140
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    Claire was your ascent rate 9m per min to the first stop or more than that and did you practice getting the pacing right or time it via your timer/computer?


 
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