M5 – Buoyancy Control

The second of the 10 golden rules of the good diver (Module 18 – The Marine Environment), is exactly a good control of the buoyancy that is required for the diver to comply with the third rule, which is to keep away from contact with the seabed and the living beings that inhabit it.

This requires the diver to pay constant attention, to maintain a good hydrostatic balance by perfect controlling the volume of his vest, i.e. the amount of air it contains. This physical phenomenon will be properly explained in Module 8 – Principles of Physics.

It is essential that the diver is trained to handle the BCD. If the technique is not perfected, there is a risk of rapid ascending and accidents, especially the risk of pulmonary overpressure.

THE INSUFFLATION AND RELEASE OF THE BCD MUST BE DONE IN A CAREFUL MANNER SO THAT THE BUOYANCY CONTROL IS NOT LOST. THEREFORE, THE AIR MUST BE INFLATED INTO THE BCD ALWAYS IN SMALL QUANTITIES.

AT THE END OF THE MODULE THE STUDENT MUST KNOW

1. The main functions of the diving BCD.
2. The essential features to which diving BCD must be obeyed.
3. The fundamental parts of diving BCD and its functions.
4. The possible ways to fill the BCD.
5. What function do the safety valves have.
6. How it should be adjusted to the diver’s body.
7. How to use the BCD on the surface.
8. How to maintain hydrostatic balance during diving.
9. What are the dangers of not controlling the handling of the BCD.
10. What care to take in conservation and maintenance.