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How to make your tank last

Discussion in 'General Scuba Diving' started by GemeenAapje, Apr 3, 2010.

  1. GemeenAapje

    GemeenAapje New Member

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    I'm sure this question has come up a lot, but I can't find any past topics so easily.

    So - how can a beginner like myself make a tank last longer?

    Even with a 15L tank I still last 30 minutes max (200 to 50 bar).

    I consider myself to be breathing calmly, I'm extremely relaxed and taking deep breaths as advised by my instructor.

    I hate being the one to cause my buddy to leave early - even in calm water.

    I also want to get my money's worth and have more than half a dive everytime

    Thanks
    ~Matt
     
  2. mala

    mala Member

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    this is so common.

    bouyancy is probably the most important.even if you feel right slight over or under neutral will mean you have to work harder and use more gas to maintain depth.

    second is number of dives-the more you do the better it will be .

    generally blokes use more than girls cos they have more blood and larger lungs.

    amount of weights-the more you have the more you have to move through the water expending energy.

    streamline your kit so that you creat as little ressistance as possible.

    be sensible with the dive-if there is no need to go right to the max depth then dont-the deeper you are the more gas you use.

    dive as much as possible and your rate will come down

    2p
     
  3. GemeenAapje

    GemeenAapje New Member

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    thanks. I will be having my first pool refresher session this week and I'll be using my new kit, integrated weights etc and a max of 5m... so i should last a long time!

    I think you're right about bouyancy though, I was yo-yoing last time
     
  4. Mike Ward

    Mike Ward Member

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    Just forget about it. Don't think about your gas consumption. It doesn't matter (well except you don't want to run out!).

    Over time you'll truly relax, and you'll get to a consumption level that is correct for you.
     
  5. Warter Boy

    Warter Boy Member

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    I find that consciously breathing as slow as possible (without actually holding your breath) has improved my air consumption and helped a lot with really fine bouyancy control.

    Having said that, my air consumption was low to begin with... To give you an idea: At Capernwray last Sunday I was using a 12l cylinder. Going in with 210bar and coming out with at least 120bar on each of the 3 dives (25-30 minutes each). Each of the dives was for my AOW too, so I was having to do various skills on each dive. If I had been diving purely for the fun of it (i.e not having to do all the different activities) I reckon I would've come out with at least 20bar more.
     
  6. bottlefish

    bottlefish Super dooper member
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    As Mala says, this is probably the most common question for a newbie diver. I asked similar when I first started out, was given all sorts of voodoo suggestions, however the one that worked the best for me was to simply forget about it.

    The fact is, your body will make you breath as you need to. Any attempts to control this will work against you, you simply build up more CO2 (the thing that triggers our desire to breath) as a result, both from the increased stress from worrying about it, and the increased CO2 in trying to control the urge to breath.

    The more you relax, the less CO2 your body will generate. So the other obvious thing that's going to help is increased comfort in the water.... the more you dive, the more you relax, the less you breath.

    Technique does also play a big part (which again, will improve with experience, and time in the water), the more neutrally bouyant you are, the less you have to work to hold position. The better your finning technique, the more streamlined your profile and equipment, the less effort you need to move through the water column.

    CV fitness does also play a part, if you're unfit, then you will naturally need more air.

    But basically, just chill... monitor your air on the dive, but accept the fact that you will use what you use, you may well see a reduction from that straight away.
     
  7. GemeenAapje

    GemeenAapje New Member

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    WB, what's your body type/build/fitness level?

    I'm a big guy, 6'2" large build (bit fat but I also weight lift). I'm highly unfit though which I think is a large part of the problem. I've been swimming a lot this week to get my fitness up.

    Thing is, I need to buy a tank but I don't know what size to get. As I said, a 15l tank lasts me half an hour before I have to stop. I don't wanna buy a 15l only to later find that I don't need so much and end up carrying all that extra weight for no reason.

    Gonna borrow a 12l from the shop and go into the pool a few times this week and see how long I last.[hr]
    thanks bottlefish, but as for WB I also find it lasts longer if I conciously breath deep and slow. Finally got this on my last couple of dives in my AOW, but it will still 30 mins max.

    I'll dig out my log book and tell you how I was...
     
  8. puddle fish

    puddle fish Well-Known Member

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    Why worry about carrying extra gas I use a 15 and get two dives out of tank.
     
  9. Gnomey

    Gnomey Well-Known Member

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    I am the same size as you are and I used to gulp down a 15l in 40 mins but now I use a 12l for my first dive and a 10 for the second and normally last a about 50mins to an hour.
    Good thing about diving in Zeelands where I like to dive is that you come out of the water, and without de-kitting you can fill up your tank and get back in again. Out the water in some places for just 2 mins.
     
  10. bottlefish

    bottlefish Super dooper member
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    Buying a 15 litre tank can be a false economy. You've increased the gas in the tank by 25%, however you've also added more weight on the surface (so have to do more work getting in, heart rate increases), will need more weight on the dive itself (15 litre tanks have a bigger weight drop from full to empty, and are more bouyant when empty then 12 litre tanks) and are much bigger, therefore far less streamlined (so you need to do more work to push yourself through the water). Net result, you may find your air consumption goes up, your tank lasts you no longer then your 12 litre.

    Personally I'd suggest holding off buying until you've got a bit more experience and know where you are... beg, borrow, steal or hire for the time being.
     
  11. GemeenAapje

    GemeenAapje New Member

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    thing is, hiring weights and tank costs 25 euros per day and if you just do one pool dive in the local baths then it's a pretty expensive thing (10 dives and I could have bought my own set!)

    I do like the idea of getting 2 dives out of 1 tank after I gain experience though.
     
  12. Warter Boy

    Warter Boy Member

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    I'm 6'2 (and a bit) and about 15 1/2 stone. I'm not what you would call fit in any shape way or form. I'm a bit squidgy around the middle (36" waist) and I smoke about 10-15 a day. Add onto that the fact that for a living I sit in a chair and watch buses drive past a window, I'm not in fantastic shape. I started running in January, but nearly breaking my ankle at work coupled with working double shifts to cover the cost of moving to Norwich for Uni in september means I seldom get chance to go. I usually dive with my own 15l tank (used the schools 12s last weekend as it saved me having to get mine refilled) and it normally lasts me 2 dives with ample reserve. I can't remember the exact details, but I remember a day at capernwray when I did 2 40+minute dives on one fill and still had about 80bar in reserve. I'll check my log book when I get home (still at work! talk about bored!!!).
     
  13. GemeenAapje

    GemeenAapje New Member

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    Thanks for the details WB. I've just checked my log and found that I didn't record times for all my dives (was out on a rubber boat for the OW so didn't note any info - instructor wasn't bothered so neither was I lol).

    Here's what I got logged from my liveaboard weekend, some dives were deep and one was at night. One was also in strong current but I apparently did well in that. Oh, and 2 dives required pickup cos we couldn't swim against the current to the boat lol (not jokin!).

    [​IMG]
     
  14. Gnomey

    Gnomey Well-Known Member

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    I can tell you now that you will not get two dives out of a 15l when you are more experianced, you will nearly always use the air for a longer dive.
     
  15. GemeenAapje

    GemeenAapje New Member

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    longer dive also sounds good. So I'll probably get a 15l then. Just so damn heavy on your back though.
     
  16. Warter Boy

    Warter Boy Member

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    Home now. I don't have a fancy computerised log (I dive with a gekko). Anyway, I've got my log book infront of me. The dives at Capernwray were as follows:

    Dive 1
    17.1m (podsnap Thumbs Up) 41min
    Air in 220bar
    Air out 155bar

    Dive 2
    16.8m 43min
    Air in 155bar
    Air out 80bar

    The notes in my log say the second dive my wife was navigating... and got us lost :lol: I'd forgotten about that!
     
  17. Major Clanger

    Major Clanger P-Plated Meg Diver

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    Stagger around with a twinset for a bit, then go back to a 15 and see if you still think the same. Breathing rate should improve with the 15 as you find ways that take less effort.[hr]
    Don't you have any lungs:)
     
  18. Warter Boy

    Warter Boy Member

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    My wife reckons I'm part fish! Those 2 dives were in 5 degree water, in March wearing a semi-dry!

    When I'm underwater I feel like I'm in my natural element. It's almost as though I'm medatating as I'm so relaxed. Another thing that helps is my buoyancy control. The last 2 Sundays have been spent under scrutiny doing AOW. I had a different instructor on each of the days and both said the couldn't fault my buoyancy control at all. I have focussed a lot on streamlining myself and I always make sure I'm properly weighted.
     
  19. puddle fish

    puddle fish Well-Known Member

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    If you can try diving with both and get the one you feel most comfortable with.

    As for the extra weight you will soon get used to it, I now use a transpac harness and wing rather than a BCD, I find it distributes the weight more evenly. My sons GF uses a 15l as that's the only tanks I have and she is a tiny size 10 but 2 1/2 years of diving and she is far stronger than she looks, and has gills as she doesn't use air.
     
  20. salty_scuba_peanut

    salty_scuba_peanut New Member

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    There's little difference in it. I'm around 5'7-5'8 and just under 10 stone piss wet through and I had no trouble with one, although I only used it once and then swapped onto twin 7s.

    According to Go-Dive there is just over a 3kg difference between a 12l and a 15l. It's not a huge difference, and it's easily manageable. As others have said, if your air consumption does improve dramatically, it'll just mean you can do longer dives.
     

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