Buoyancy Control, dive like a pro !

DJL diving instructor James returned to Koh Tao to help us out after spending some time in Australia. While he was here he wrote an article for the DJL blog with some great tips about perfecting buoyancy control. Buoyancy training can be included as part of the Advanced Open Water course or as a separate Speciality course. For more details about this contact us here and our staff will be happy to answer any questions.

“Pinpoint buoyancy control separates the dive paddlers from the pros and elite divers. It all begins with the fine tuning of your weighting system which can take several dives to get right. By carrying just the right amount of weight, you would float at eye level holding a normal breath with a completely empty BCD and with your tank at around 50 bar as this is when you should surface and the tank is near its most buoyant. In turn this will result in you requiring the smallest amount of BC inflation, less drag and more efficient fining. With less BC inflation comes less buoyancy shift with depth, so you’ll make fewer adjustments.

Buoyancy Control, dive like a pro !

Other factors which affect your buoyancy besides ballast weight are BCD inflation, trim, exposure suit type and condition, depth and breath control. Take the PADI Peak Performance Buoyancy which teaches precise buoyancy control, streamlining, weight and trim adjustment, equipment configuration options and relaxation techniques.

New equipment can be a major factor in potential change of personal weight requirements. A new wet suit will need more weight than an old one as they are more springy because they contain more ‘bubbles’ within it. New BCD’s may have an effect due to their internal volumes when full and so in turn when empty. New cylinders i.e. Steel cylinders are constantly negatively buoyant but obviously less so the closer you get to empty. Aluminium cylinders are negatively buoyant when full and often positively buoyant when empty.

Buoyancy Control when descending

On descents deflate your BCD and exhale to sink down slowly. Periodically add controlled bursts of air to control your descent rate. By the time you reach your intended depth the elite diver will be neutrally buoyant which comes from experience. As you swim round, things that you want to see may be slightly higher or lower than your current depth. To reach things that are slightly higher than your current position, inhale a little more than usual. This will cause you to be more positively buoyant and therefore rise up.  Exhaling sharply helps to control the ascent. Obviously when things that are slightly lower than your current position the opposite is true. Exhale a little more than usual which will cause you to be more negatively buoyant and therefore sink. Inhale sharply to control the descent.

Buoyancy Control when ascending

On ascent periodically release expanding air from your BCD. The biggest cause of runaway ascents in divers is failure to adequately (or at all in some cases) release this air. This leaves people at risk from both decompression sickness from an accelerated ascent and also ‘blowing their safety stop’. Another potential danger is lung over expansion injury.

Finally, make your safety stop count. Use this 3 minutes you get at the end of each dive more productively than staring at a rope or the bottom of a boat. Stay neutrally buoyant and fine-tune your buoyancy and trim position.”

 

James