When I first started scuba diving, it wasn’t the whole “breathing under water,” thing that I struggled with the most. I was fortunate in that I didn’t suffer any anxiety on early dives.
But one of the things I did struggle immensely with was buoyancy control. Let’s face it – the human body isn’t made for maneuvering with any degree of elegance under water. And for me, buoyancy control is something that still doesn’t come naturally.
But with the help of some far more advanced divers than myself, I’ve become more accustomed over time to controlling buoyancy. The benefits of great buoyancy control include:
• The ability to get your dive mask up close to marine life without disturbing them
• You’ll use les air on dives
• You’ll feel far less fatigued at the end of your dives
What affects scuba diving buoyancy?
There are 6 things that affect buoyancy control when scuba diving:
• Your ballast weight
• Your BC inflation
• Exposure suit buoyancy
• Breath control
Of course, most of the above vary depending on a host of factors and controlling them isn’t as easy as we might like. But here are a few tips and tricks to help you better control buoyancy on a dive:
Cut the weight
We’re not telling you to diet! Most scuba divers are overweighted when they dive. Instructors commonly accept this. In some cases, instructors actually admit to encouraging over weighting to aid students, but this can cause problems later on.
So, the first step is just drop a couple of pounds of lead. Give it a go! You might find you can’t get below the surface initially, but before you go adding more weight, you should try a few other steps:
• Make sure your suit is completely wet. Give it a couple of minutes from getting in the water to ensure all the material is wet
• Try to relax. Many scuba divers are tense without realising it and move their limbs perhaps more than they realise. So try this positioning:
o Place your right arm by your side
o Hold up your exhaust hose with your left arm
o Extend your legs right out and have them pointing downwards
o Have your fins point completely downwards to
• Breathe out! Another thing many of us divers do without even realising it is holding our breath. Breathe out. It will help!
Taking care of the above is a good start. You might find you don’t need as much weight as you thought you did to descend
Getting your trim right
Your position in the water has a huge impact on your ability to control your buoyancy. While most beginner scuba courses teach about buoyancy control, not all of them even mention trim. It’s surprising, considering the impact one has on the other.
Consider this: if your fins are lower than your body in the water, a kicking motion to propel yourself forward will also have the impact of propelling you upwards! That will make you feel that you’ve become buoyant and you’ll generally then vent air from your BC. The effect of that will be that you will become too heavy and sink.
What we’re saying, in short, is that you need to ensure your position in the water is such that your kicking doesn’t interfere with your buoyancy. This means your legs should be pretty much horizontal. A good way to check on your trim is to put yourself in a neutral position, hold yourself with your legs stretched right out behind you. If your legs sink, move some weight from your waist to a point a little higher up on your body.
The weight of your tank
We all know that as we use up air in our tanks, the tanks get lighter. So you will need to remember to compensate for this shift in buoyancy throughout your dive.
Things to consider about your exposure suit
Your suit will become less buoyant over time. Neoprene traps gas in tiny bubbles and that makes it buoyant. A thin tropical suit of just a couple of mm thick neoprene will have a near negligible surface buoyancy (almost certainly 2lbs or less). On the other hand, cold water suits are much thicker and could have 20 lbs of buoyancy.
You will, of course, become accustomed to your own suit. However, the thing to bear in mind here is that as your suit becomes more worn, the bubbles of gas collapse or fill with water, meaning your suit becomes les buoyant. So over time, you may have to adjust other factors to compensate.
How depth affects buoyancy
Whatever type of neoprene suit you have, the depth will influence its buoyancy. At deeper levels, the bubbles we talked about are compressed and the suit therefore becomes less buoyant.
Most of the impact is in the first few feet, but it something you should be acutely aware of and should make the necessary changes to allow for it.
Controlling your breathing
This is so hugely important. Scuba diving buoyancy is affected by how you breathe – it’s as simply as that. Your lungs are your body’s own natural buoyancy compensator. Use them to your advantage.
Consider this – a normal resting breath would expand your lungs by around a pint. This in turn gives you one pound more buoyancy. However, you can choose to put that one pound shift anywhere in that 10 pound range.
So, you could breathe with almost full lungs and stay between 8 and 9 pounds of buoyancy, or you could breathe with emptier lungs and stay between 2 and 3. This basically means you can use your lungs to rise and fall easily.
The full picture
When you become aware of things that influence your buoyancy and you begin to be able to predict when shifts and changes might happen, you can simply use your BC to compensate. Using your BC isn’t the tricky bit with scuba diving buoyancy control – the tricky part is knowing when to use it. And mastering the above is a great start.
Of course, buoyancy control, as with anything, will take time to truly master. But keep at it!
For scuba diving BCDs, we recomend Simply Scuba.