Scuba Diving - Section 2

- Contrast the differences in heat loss between air and water and describe the effect of heat loss on the body while diving.

While air is an excellent insulator for blocking heat transmission, water is an excellent conductor. Water absorbs your body’s heat 25 times faster than air does.

The body’s primary responsibility is to keep the brain and torso warm. If the body can no longer do that, a phenomenon called blood shunting occurs. This is when circulation to the outer extremities of the body is slowed, in order to preserve blood and warmth for the brain and major internal organs. It is not good for you if you are underwater.

As depth increases, pressure increases. This increase in pressure causes the amount of Nitrogen, which you breathe in, to increase in the bloodstream and tissues. The Nitrogen is transported from the lungs through the circulatory system and into the tissues. The build up of Nitrogen in the tissues limits our time underwater and divers must control it by regulating time, depth, and rate of ascent. In order to control the process and have proper absorption and elimination of this nitrogen, it is important to remain warm throughout your dives.

- Describe the most effective and efficient breathing pattern for SCUBA.

Recreational divers can also take advantage of the latest diving technology. Closed circuit, electronic rebreathers are similar to the Primary Life Support Systems used by astronauts. They recycle and recondition the gas breathed by the diver and provide increased dive time. Because there are no bubbles, divers can frequently get much closer to marine life they wish to observe or photograph. 

The most efficient breathing pattern for scuba is a deep inhalation followed by an even exhalation — deep, balanced and rhythmic. The key is to relax in the water and realise that your breathing pattern will automatically become normal with experience.

- Explain why a diver’s gas consumption increases as depth increases and identify at least four factors that can affect gas consumption rate while diving.

While at rest, we normally breathe about 6 to 12 litres of gas per minute. A warm and comfortable adult diver with minimal experience will breathe 12 to 15 litre per minute. This is useful as our scuba cylinders are rated in capacity by the amount of gas they hold in litres. For example, a 12 Litre cylinder filled with 200 bar (the most common cylinder) would last a diver with a surface consumption rate of 15 litres per minute a total of 160 minutes. A simple formula can be used to determine how long a cylinder of gas will last you at any depth.

- List the individual components of a Delivery System and describe basic functions of each component.

The Delivery System includes a regulator, alternate air source and a high pressure scuba cylinder.

• The purpose of a scuba diving regulator is to reduce the high-pressure air in a scuba tank to a breathable pressure on demand.The regulator…