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Mastering Buoyancy Control

Discussion in 'DIR Diving' started by Gareth Burrows, Jan 26, 2011.

  1. Gareth Burrows

    Gareth Burrows Super Moderator
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    I had a lot of hits on an article I wrote about the importance of buoyancy control (see here)

    However, I also had a lot of questions from people asking if it was so important, were there any useful tips and tricks I can use to further explain the concept. Of course there are. I thought I'd post them up here....

    So. In the last article, we discuss the importance of buoyancy control. We also defined it. As a reminder, we defined it as a conscious control of the balance between the items of our equipment that are attempting to sink us, with the items of our equipment that are trying to float us. At first glance, this would seem to be easy. We have thr gas in our wing, our drysuit, and our lungs trying to send us to the surface, and all the heavy junk we have strapped to us trying to send us to the bottom. And indeed, a macro level control of these elements is within the grasp of most divers.

    True buoyancy control is, however, not done at a macro level. True buoyancy control uis a fine control, not lost when distracted or task loaded. this sort of control takes decent training, and a considerable amount of practice.

    So are there any shortcuts?

    Firstly, let's talk about what neutral buoyancy really is. Picture a descent. The diver drops onto a wreck at ten metres. They left the surface negatively buoyancy, and it's fairly safe to assume that they remained negatively buoyant all the way done to the bottom, else they would have arrested or at least slowed their descent. now they begin to add air into the wing. Just before they hit the bottom, they take a big lungful of gas and stop their descent, floating gracefully above the wreck They are not going up. they are not going down. Are they neutrally buoyant. No.

    The reason I saw not is because they are not in control of that balance. A diver in this position, and I must add that this consists of the vast majority of all divers that come to me for training or coaching, will now be breathing in the upper half of their lungs. They have to, because if they breathe out fully they will become negatively buoyant and will begin to sink. You can see this clearly with divers that are distracted by something. they forget about their breathing, breathe out fully, and end up planting a hand on the wreck, not knowing why they have suddenly become negatively buoyant. When they have better contro, it might just be a finger bouncing on the wreck every now and again. Neither diver is truly neutrally buoyant. Of course, you only see this when the diver stops, because all the time that they are finning along they are unconsciously compensating for this negative buoyancy. they are also going to get more tired, and use more gas, because they are not breathing efficiently.

    Let's step away from that diver for a moment, and really think about what we mean when we say "neutral buoyancy". Neutral buoyancy, for me, is when a diver is vertically motionless in the water column, when they have HALF a lungful of gas. When they breathe in fully, they will be slightly positively buoyant. When they breathe out fully they will be slightly negatively buoyant. In the middle of their lungs, they don't move.

    So here is the first tip. Find neutral buoyancy and get used to how it feels

    Next time you are in the water, and not finning around. Take a few deep, slow breaths, then let half a breath out and stop breathing at that point. try to avoid waggling your fins or your arms. Do you stay exactly where you are, or do you drift up or down. By fine tuning the amount of gas in your wing you can now get yourself truly negatively buoyant, which as we have discussed in the first article, just makes everything easier.

    Let's go back to our diver on the wreck. He has the same issue when ascending and trying to hold a safety stop. He gets to his safety stop depth, but he's a little light so he breathes all the way out to keep himself at the right depth. now he has the opposite problem to the descent. He can only breathe in half way. again, I see this a great deal. When you write down the fact that the diver cannot take a full breathe without affecting his buoyancy control, all of a sudden that safety stop sounds like hard work.

    So here's tip 2. If you are not breathing correctly at any point in the dive, stop what you are doing and sort your buoyancy control out. You will immediately feel less stressed and you will enjoy the dive more.

    I vizualise buoyancy control like a see saw. If you are standing on the centre of the see saw, you can make very small adjustments quite easily by leaning one way or the other. However, if you make a large adjustment, its very difficult to come immediately back to the centre. You will tend to rock back and forth a bit until you manage to get it level again. Let's take that analogy underwater. the centre of the see saw is neutrally buoyant. standing in the centre and making small changes is the equivalent of making small adjustments with your lungs. Making big steps along the see saw is the equivalent of using macro controls such as the wing dump, or the wing or drysuit inflator. It is far more difficult to make a macro change and get it precisely correct.

    Let me demonstrate what I mean. At six metres I can initiate an ascent, stop it, and regain neutral buoyancy at 5 metres, without going near my wing. I might then make a tiny adjustment to my wing so that i am able to breathe comfortably. If I rush to inflate my wing at 6 metres, it is far more difficult to do a precise dump of gas. Just like the person on the see saw, I am more more likely to overcompensate and end up negatively buoyant again. This is again something I see often. People trying to achieve a stable depth alternative between positively buoyant and negatively buoyant. They overcompensate each way. eventually they get it under control, but this takes time and effort. It's far easier to do the same thing with micro changes.

    So here's tip number 3. Use your lungs to make micro changes rather than you wing or drysuit.

    When you are cooking, and you want to add 300 grams of flour, do you try to pour it on to the scales all in one go, and put it back in the bag if you add too much. No, that would be a little foolish. what you do is add a bit, then a bt more, then a bit more, until you reach the correct weight. Let's take that one underwater. The overcompensation I was talking about earlier occurs because divers who are approaching a target depth panic or worry about stopping and either put one huge burst of gas into their wing, or dump it all out. then there is a cascade of overcompensation, wasting gas, stressing the diver, and taking time to resolve. A much more effective technique is to put small bursts of gas int your wing, or let small amounts out. It is easier as your hand is already in the right place to do a little more, than to switch between inflating and deflating, and vice versa.

    Tip Number 4. Use lot of small adjustments to correct or adjust your buoyancy rather than one large change.

    Let's stay with the cooking analogy a little earlier. If you are boiling milk, it is a somewhat foolish strategy to watch the milk boil over, and then turn the gas off. It's far more effective to watch for the signs that the milk is going to boil, then switch the gas off in time to stop the milk climbing up the sides of the pan. So let's take that one underwater. If you are descending towards a wreck, the time to reach for your wing inflater is not when you are two feet above it. you are going to smash itno the wreck, send up a cloud of silt, and general looking like you are. Out of control. Similarly, if you are ascending towards a planned stop depth, whether it be a decompression stop or just a safety stop, its too late to control that stop when you are at the right depth. One of the true keys to accurate buoyancy control is pre-emptive action. If i want to move from six metres to 3 metres, my hand will be at the dump by four metres and dumping by 3.5. By the time I get to 3 metres i should have arrested my descent. This pre-emptive action also applies to the bottom part of the dive. When you are swimming around, if you swim over a part of a wreck and ascend a few metres in the process, your training should tell you that this will have a ramification on your buoyancy. don;t wait until you are starting to ascend away from the wreck. Be ready to dump as you are moving up it. you know it's going to happen so there's no need for you to wait for the laws of physics to prove they are still in place. If it takes you a degree of time to get your hand into place to dump or insert gas into your buoyancy device, then include that time in your anticipation.

    Tip Number 5. Pre-empt buoyancy changes and act in time. Anticipate what will happen rather than wait for it and you will remain in control.

    My final point, is to make life easy for yourself. So what can make life difficult. Being overweighted is probably the most common problem I see. People overweight themselves, often ironically in a misplace belief that it will help avoid a rapid ascent. In fact the opposite is true. If you are overweighted, you need a bigger bubble of gas to compensate for all that extra lead. When it's time to ascend, along come those pesky laws of physics again. he bubble expands, and now you have a bigger bubble of gas to contend with than if you were correctly weighted. Now, this does not mean weight yourself correctly to the gram, but I've taken 17Kg off people in the past. Significant overweighting is not your friend. the other thing that make life easy is practice. No-one jumps in the water and is instantly proficient. Proficiency takes practice. Try moving up and down a line between 4 and 6 metres. Get used to movign and stopping. Get used to stopping at a depth you wanted to be at. Learn how much to dump when changing depth, or how much you need to add to stop a descent. Once you get a feeling for all of this, the rest becomes so much easier.

    and that's my take on buoyancy control.
     
    AdsDiving833 likes this.
  2. Flyingspanner

    Flyingspanner Well-Known Member

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    Thanks Garf
    I'm just moving onto a wing, I shall take your advice on board.

    FS
     
  3. Air-Guzzler

    Air-Guzzler Cannot spel and I cannut delet your post :-)

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    Nick
    Come to Cappers on Saturday I know a couple of people will be trying a few things out again that will help you understand the above article
     
  4. Imogen

    Imogen New Member

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    :D enjoy!!! I#ll be doing just that on monday too....mustn't forget the loo roll ;)
     
  5. starwatcher

    starwatcher Member

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    Excellent article Gareth, cheers!

    Think there's a typo*. Did you mean neutrally?

    All the best,

    Mark

    *just proving I've read it :)
     
  6. Imogen

    Imogen New Member

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    Thanks for the proof read....now corrected on divedir site too!!! ;)
     
  7. big si

    big si Well-Known Member

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    just goes to show how many people read something and have no idea what your on about, or understand what you trying to explain.
     
  8. Air-Guzzler

    Air-Guzzler Cannot spel and I cannut delet your post :-)

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    Well for somebody who has experienced what Gareth has described I would like to say to ALL of those divers that have In there own mind goody bouyancy skills.

    Go and try it.

    descend to 6mtrs and settle yourself.
    then rise from 6-5 and wait 1 min
    then rise from 5-4 and wait 1 min
    then rise from 4-3 and wait 1 min
    then rise from 3-2 and wait 1 min
    then drop back down to 5.


    When you have done that come back and tell us how easy it is :)
     
  9. Suggsy

    Suggsy Banned

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    What about 2-1?[hr]
    Also, we started at 5m mate.
     
  10. Air-Guzzler

    Air-Guzzler Cannot spel and I cannut delet your post :-)

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    That depended on who's computer you where looking at ;)
     
  11. Gareth Burrows

    Gareth Burrows Super Moderator
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    and then go do it again whilst putting up an SMB on the way to distract from the buoyancy control :)
     
  12. indyblade

    indyblade Member

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    Fascinating article, printed it off for future reference, Slightly off the original thread I was amazed at what type wetsuit you wear affects bouyancy, and yes I can see the benefits of a dry suit as you would only have the floatability of the water to compensate for weightwise. I dive in a 7mm semi in the UK and need 12kg to get me neutrally bouyant in fresh water, when I was in turkey I dived in a 3mm shorty with all my own gear and thought I'd be more floaty with it be salt water but only needed 6kg.
     
  13. Major Clanger

    Major Clanger P-Plated Meg Diver

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    Then do it without any references. That rise from 4 to 3 gets me every time.
     
  14. Gareth Burrows

    Gareth Burrows Super Moderator
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    There's nearly always a visual reference. Instead of focussing on your team mate, allow your eyes to defocus slightly. You will still be in place for your team mate if they have a problem, but you will be able to focus on the particulates in the water. As a general rule, if they are not moving, neither are you :)
     
  15. Major Clanger

    Major Clanger P-Plated Meg Diver

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    Good suggestion. Last time I tried it those particulates wouldn't do as they're told. Nothing to do with fins swirling things up, honest.
     
  16. big si

    big si Well-Known Member

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    6m to surface in 1m incrament for 1 min every metre isnt any special circus trick if your familiar with deco diving you should be able to do this second nature ;)
     
  17. Major Clanger

    Major Clanger P-Plated Meg Diver

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    Behave yourself big chap.
     
  18. Suggsy

    Suggsy Banned

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    I don't believe anybody did say it was a 'circus trick'. We all aspire to one day have your internet diving skills, or just not care and just get on with it thankful of helpful instructors such as Garf, who are willing to take the time to help others.
    Saying that I bet you've no need for fins with those clown shoes.
     
  19. big si

    big si Well-Known Member

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    woops, iv upset the monkey and its jumped out of its tree
     
  20. Major Clanger

    Major Clanger P-Plated Meg Diver

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