08. IDEAL BUOYANCY

Being suspended in mid-water with neutral buoyancy can be compared to being in a helicopter hovering in the sky. It’s the ideal position to observe the splendor of the surroundings. Having the ability to control our position — through ideal buoyancy, allows us to easily approach objects and creatures without the worry of running into, and potentially damaging them, or injuring ourselves.

When discussing optimal buoyancy, the first thing to consider is proper weighting.

Remember, establishing proper weighting is not a “one-and-done” scenario; weight requirements will likely be different after adjustments to equipment configurations, changes in exposure protection and in new diving locations.

To determine how much weight you need, take the following steps in water deep enough for you to be able to completely submerge while upright: enter the water fully equipped, assume an upright position, and deflate the BCD completely. Hold your breath with your lungs approximately half full (the amount of a normal breath).

Watch the Video: Weight Check

When ideally weighted in this position, and without moving, the water level should be at eye level, or splitting your mask lens in the middle. Add, or remove weight as necessary to achieve this positioning.

Once you’ve reached ideal weighting for the position described above, you should start to sink by slightly exhaling and start to float by inhaling.

After you’ve determined your correct weighting, you are ready to descend.

It’s recommended to make your descent using a descent line, or the anchor line of a boat. Maintain visual contact with the line, and stay within arms reach, should you need to hold on to the line for any reason. In an upright position, begin your descent by deflating your BCD completely and slightly exhaling.

It is important, during the first phase of the descent, not to exert opposing thrusts such as strong kicking or inhaling large amounts of air.

 

Watch the Video: Descend and Equalize

 

Once below the surface (about 4-5m/10-15ft) you should establish a horizontal position and continue descending. It is essential to perform a controlled descent, which allows you to monitor the instruments and correctly perform the compensation maneuvers, for this you must maintain a normal breathing rhythm.

Due to Boyle’s Law, as your depth increases, you will become more negatively buoyant. Consequently, it will be necessary to slightly inflate your BCD to counteract the increase in pressure. Gently add gas to your BCD in small increments, pausing after each time to allow the gas to expand.

Check your buoyancy and add gas as necessary to maintain a slow descent. Once you’ve reached your predetermined depth add small amounts of gas to your BCD until you no longer sink, if you are weighted correctly, it should take very little additional gas in your BCD to achieve neutral buoyancy.

The diver with buoyancy experience and control reaches neutral buoyancy at the same time that he reaches the predetermined depth, this is a goal you should set for yourself and become an SNSI Master Buoyancy & Trim Diver.

M

Advanced Open Water Diver