The six factors that affect your buoyancy are your ballast weight and your BC inflation, of course, and also your trim, your exposure suit buoyancy, your depth and your breath control. All these factors vary throughout a dive, the only two that remain the same are your trim and ballast weight. Some you can control, some you can’t. Buoyancy control isn’t as easy as it looks.
Lets go into some more detail about these six factors…
The ballast weight you carry doesn’t change during a dive, but it’s often the biggest problem. Many if not most divers are, carrying more lead than they need.
Most instructors during an open water course will overweight their students, it’s not a wrong thing to do, its very similar to a parent putting training wheels onto a kids bike when they are learning to ride it, only trouble is those training wheels need to be removed to progress on from the novice stage. This is a reason why the Advanced course is so advantageous to most open water students, you learn the basics of diving during your open water then during the advanced you get time with the instructor to really refine your diving.
The first step is to just do it–take off 1kg before your next dive. Can’t get below the surface? Before you reach for the lead again, make sure you really need it. Getting below the surface, especially on the first dive of the day, can be surprisingly difficult and can trick you into carrying more lead than you really need. Here are a few tips:
Be patient- especially when wearing a wet suit, it may take time to get that wetsuit fully soaked through.
Reach up. Hold the inflator hose over your head and stretch it upward a little so its attachment point to your BC is highest. This is the main problem students have when trying to deflate, if you don’t hold that inflator hose all the way up you will still have trapped air in your BCD.
Relax. Without realising you may still be kicking your legs and moving your arms, its just nerves, without realising you are kicking your way back to the surface.
Exhale.Exhale and hold it until you start sinking, holding a lung full of air is another manifestation of nerves, it also adds a lot of buoyancy and can be the difference between going down or not, exhale and take shallow intakes of breath until you are below 2 meters.
Force it. Last method, try to force your decent by generating some downwards thrust and kicking down.
Once you are correctly weighted the most important factor to consider is your trim. Trim is your positioning in the water, we want to be completely horizontal in the water, if you try to swim with your legs slightly lower than the rest of your body then whilst your trying to kick to go forwards you are also kicking yourself to the surface. this will cause any air in your BCD to expand so when you vent this you are also making yourself negatively buoyant. if you remain in perfect trim through your dive you wll end up fiddling with your BCD a lot less and conserving a lot more air. Perfect trim is what we aim for in diving and is also helped by the Peak Performance buoyancy speciality.
Tank weight is another thing to consider when diving, especially when using aluminium tanks, you will be considerably heavier at the beginning of a dive than towards the end of a dive, thankfully this change of weight is gradual, so the change wont come as a surprise and you can adjust for this buoyancy change gradually throughout the dive.
There is no escaping the fact that wetsuits make you more buoyant, the tiny neoprene bubbles inside a wetsuit will cause gas to get trapped and the deeper you go the less buoyant your wetsuit will make you. The good news is once you have your buoyancy dialled in at a given depth the buoyancy wont change unless you change your depth. Many people in the tropics wont wear wetsuits to avoid this problem however in some circumstances wetsuits/dry suits are essential. practise makes perfect when using wetsuits, and the thicker the wetsuit the more buoyant it will make you.
Breath control is the most important way to maintain good buoyancy, its the way you want to learn to eventually dive, as long as you remain neutrally buoyant with lungs half full you can exhale and sink and inhale and rise, this will gradually increase the effectiveness of your air usage, if you don’t need to waste air by inflating and deflating your BCD underwater and just use your lungs to control your buoyancy it will give you longer dives.
Putting it all together
Once you have mastered all of this you can start putting this together, the best thing to do is get diving, the more practice you have the more time you have to play with your buoyancy, the end result being that perfect photo or being able to be inches away from the reef without harming it in anyway, your instructor or dive master will applaud. The peak performance buoyancy speciality will be a massive step up to helping you along the way with achieving this.