How to Place Your Tank for Perfect Buoyancy: Tank Up or Down
There is one little trick to buoyancy control that many divers miss: where they place their dive tank!
Buoyancy control is by far the most important skill for scuba divers. It makes it possible to maintain your position in the water column, it reduces air consumption, it makes diving less stressful and more enjoyable, and a whole load of other advantages.
Improve your buoyancy
And there are number of things that can be done to improve your buoyancy. First and foremost, if you’re an entry level scuba diver, take an advanced scuba course, and make buoyancy training a part of your training. You could also consider taking a buoyancy specialty course, or simply pay for a few dives with an instructor, where he or she helps you practice your buoyancy skills.
Simply diving more is also important, as more experience leads to better buoyancy control. Making sure you’re properly weighed is another important element. All of these elements (and arguably more) are part of the entire package of perfect buoyancy control.
Place your tank correct
But there’s one thing I’ve noticed many divers, even experienced ones, neglect to consider: the placement of their dive tanks. Of course, unless you’re a sidemount diver, you’ll probably wear your tank on your back, but how high or low can be key.
How high or low on your back (when standing) is a major element of your trim control, that is, how close to horizontal your position is in the water.
Too high tank placement
Place your tank too high on you back, and the weight shifts forward, pushing your torso towards the bottom. This will inadvertently lead you to inflate your BCD more to compensate, which then gives you too much buoyancy, meaning you need more weight to stay down. And presto, you’re overweighed and your buoyancy control is gone.
Too Low on your back
Put it too low, and the problem reverses. Your legs drop, meaning when you fin, you’re doing so in a position that is too close to vertical, meaning every fin kick actually, to some extent, pushes you towards the surface. To counteract this, you either put too little air in your BCD or put on too much weight to compensate.
This means that as soon you stop swimming, you start sinking. Then you inflate your BCD more, and when you start swimming again, you head for the surface, making you deflate your BCD again. So you spend the dive deflating and inflating your BCD, losing you air and making for a complicated dive.
How to solve the tank placement
Unfortunately, there’s no magic formula for where the tank should go. The only way to nail it is by trial and error. If you have your own tank, or you dive regularly with the same dive operator (provided they have only one type of tanks), the process is quite simple. During a dive, take note of your buoyancy and trim. Then, on the next dive, try and adjust it a bit up or down and note the difference. Adjust more up or down over the subsequent few dives and see what happens.
Over the course of a few dives, you’ll figure out where you want it placed. Do not change any other factors on these dives. So don’t also change your weight, suit or any other factor, as this would make it difficult to isolate the effect of the tank placement.
Not using same dive tank
If you habitually dive with different dive operators, maybe because you do most of your diving on holidays, it gets a bit trickier. Here, the trial and error takes on a further element as you need to figure out the ideal placement for different types of tanks, longer, shorter, aluminum, steel, etc.
In this case, taking note of the various factors in a notebook or in your dive log can help you keep track. Over a number of dives with various types of tanks, you’ll start to have an idea of what is the ideal placement for a long, 15-liter tank versus a short one. Or a 12-liter one, or one made of steel, or any other variation.
Over time, you’ll be able to make a reasonable guesstimate on how to place a type of tank that you haven’t used before.
How do you place your tank?
Do you have any personal tank placement preferences? Or any advices for your fellow diver to find the perfect trim by placing the tank in a certain way, share it in a comment below.