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  1. #1
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    Diving with stages (Ali 80 vs Ali 7)

    Up until last year my normal kit was twin 12ís and 7l 232 bar Ali stage. I use to weight myself without the stage and not change it when I used the stage.

    This year I brought an Ali 80 207 bar stage. So far I have not changed my weight. When I used it and breather it down to 145 bar noticed the stage went neutral in weight.

    Couple of questions when diving with an Ali 80 stage.

    Do I need to add additional weight, when the stage is breathed down to closer to zero since it is more buoyant then the 7L stage?

    If I need additional weight would you add it to your normal weight belt etc. or add the weight to the stage?

    cheers guys

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    Personally, I would weight myself to be able to hold a shallow stop with it all almost empty but then I'm using a CCR and so that extra float will be even more difficult to handle if it wasn't balanced out. That said, it shouldn't be too much on a single ali 80 (there's a calculator around somewhere that no doubt someone will post in due course but a couple of kg only IIRC).

    If I was diving OC, I'd definately ensure I could hold a stop with ~20bar in the back gas and a similarly virtually empty stage and the extra weight would go as a vee or tail weight depending in trim requirements. Damn OC setup is hugely overweighted most of the time anyway so an extra kilo or two won't hurt.

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    GUE Instructor Badger's Avatar
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    I wouldn't change anything for diving either one or both. But that is based on one particular configuration.

    Sent from my super dooper S4 when I should probably be doing somthing else.
    GUE Instructor

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    cheers guys with the 7 with about 10 bar and twins with 50 bar i can hold a 3m stop. Not tried it with the ali 80 at 20 bar.

    On the next dive with the ali 80 might just add 2 kilo's on and see how it feels. If its to much i try it with a kilo.

  5. #5
    Last of the Mohicans gobfish1's Avatar
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    Quote Originally Posted by Keith Wood View Post
    cheers guys with the 7 with about 10 bar and twins with 50 bar i can hold a 3m stop. Not tried it with the ali 80 at 20 bar.

    On the next dive with the ali 80 might just add 2 kilo's on and see how it feels. If its to much i try it with a kilo.
    can i ask why you feel the need for a ali 80 . over a 7 for a one deco cylinder dive ,

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    Reasons why i got the Ali 80

    It was the same price as the 7.

    When i do 2 deco dives per day the reserve for the second dive was getting small. Also after the second dive i can air top and get 50% fill, so if i am diving the next day i do not need to get any deco gas.

    If i can not get my twins filled on the boat between dives, i can use the Ali 80 as a bottom gas for the first dive keeping most of my backgas and still deco out on my 2nd stage. Then on the second dive just use the twins and the stage like normal.

    Also I am going shetlands in July and we have been told we can only take air and 02 over with us. So taking 2 stages of 02 i can get air tops to make 80% and i do not need to buy any deco gas while away.

  7. #7
    Red Hot Totty ;) Hot Totty's Avatar
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    Quote Originally Posted by jturner View Post
    Personally, I would weight myself to be able to hold a shallow stop with it all almost empty but then I'm using a CCR and so that extra float will be even more difficult to handle if it wasn't balanced out. That said, it shouldn't be too much on a single ali 80 (there's a calculator around somewhere that no doubt someone will post in due course but a couple of kg only IIRC).

    If I was diving OC, I'd definately ensure I could hold a stop with ~20bar in the back gas and a similarly virtually empty stage and the extra weight would go as a vee or tail weight depending in trim requirements. Damn OC setup is hugely overweighted most of the time anyway so an extra kilo or two won't hurt.
    I asked a similar question on mod2 - was told simply weight yourself normally and if you find it difficult to hold stop with light bail out tanks flood or partially flood the unit - it's not working after all
    www.wapsac.co.uk
    Apparently becoming a grandad

  8. #8
    Old but keen Mark Chase's Avatar
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    I use a Al80 for my 50% and if I empty it I can just let it float up on its own. I use a steel 10 for trimix as it floats nickley when full with 18/45 then floats again nicly when empty.

    Ask Digger I dangled a floaty steel 10 in front of his nose to prove a point

    AL80s empty can be a PITA if you need them all the way up.

    For shalow dives (50m max) I used two steel 7s because deco was much quicker on 32% and 80% than it is on just 50% and they balance out nicly getting floaty at arround 100bar but not so much they drag you up

    You cant realy use a single steel 10 for Nitrox deco as its too heavy on one side which is why I always poped for the 2 7s

    ATB

    Mark

  9. #9
    Last of the Mohicans gobfish1's Avatar
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    Quote Originally Posted by Keith Wood View Post
    Reasons why i got the Ali 80

    It was the same price as the 7.

    When i do 2 deco dives per day the reserve for the second dive was getting small. Also after the second dive i can air top and get 50% fill, so if i am diving the next day i do not need to get any deco gas.

    If i can not get my twins filled on the boat between dives, i can use the Ali 80 as a bottom gas for the first dive keeping most of my backgas and still deco out on my 2nd stage. Then on the second dive just use the twins and the stage like normal.

    Also I am going shetlands in July and we have been told we can only take air and 02 over with us. So taking 2 stages of 02 i can get air tops to make 80% and i do not need to buy any deco gas while away.
    thanks for your reply .
    i only ask as i used to dive twin12l,s and could not run up the deco to need a ali80,

    most of my time id be on air back gas and deco on o2 and maybe something other ie 57 64 nitrox and id only use 300l or 400l from both cylinder,s of mix, often do two 50m plus dives on one set of 7ls , buddys on ccr so no need for me to look out for them gas wise,

    Id rather have a 3l of o2 , than a ali80 of a low pp2 nitrox , i say low as most stops are 12/m and up , on the diving i was doing . or could do on a set of 12ls

    3l 5l 7l were my mix of cylinders,

    also one deco gas seems to be all your eggs in one place ,

    but if your thinking of topping off and the like then maybe the ali80 will do that for you ,

    best ,
    Last edited by gobfish1; 28-05-2014 at 06:53 PM.

  10. #10
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    Quote Originally Posted by Hot Totty View Post
    I asked a similar question on mod2 - was told simply weight yourself normally and if you find it difficult to hold stop with light bail out tanks flood or partially flood the unit - it's not working after all
    Can't be sure if you're joking or not but assuming you aren't, I'd rather not have to go to such an extremity, especially in a hurry and whilst trying to maintain a stop!


 
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