Monday, January 5, 2009

Scuba diving: Fitness required

Life on earth, and even the embryological development of individual life, has its origins in water. Even the mineral composition of seawater is remarkably similar to that of human blood. And over millions of years, everything on the earth returns to the sea through erosion and other geological phenomena. 37 phyla of life forms have been identified so far on earth and 34 of them can be found in the sea – that’s 92%.

Water is 775 times denser than air; a few feet of descent in water is equivalent to descending several hundreds of feet in atmosphere. The pressure increases by 1 ATM for every 33 feet descent into the water – which means, the pressure exerted on the body is twice as much at 33 feet as it is on the surface, thrice at 66 feet and so on…

As the specific heat of water is 1000 times that of air, it takes 1000 times more heat energy to warm up a given volume of water than the same volume of air – by one degree. Moreover, water takes away heat from a body 25 times faster than air does. Therefore the number of hours an individual can survive in cold air is approximately equivalent to the same number of minutes he would survive in water of the same temperature.

Sound conduction is 25 times greater in water than in air; it becomes almost impossible in water to tell where the sound is coming from. With depth, illumination and colors are lost. At 33 feet, red disappears and at 75 feet, yellow is lost. Things appear uniformly blue-grey, which might lead to disorientation – even way up or way down might get confusing beyond such depths.

Nitrogen in the compressed air that is breathed by divers is capable of setting off nitrogen narcosis. Every 50 feet of descent into the sea, breathing compressed air from the cylinder, the narcotic effect of nitrogen becomes equivalent to consuming one large peg of whiskey. At 200 feet, it becomes equivalent to having had four drinks. The effect varies according to the diver's constitution.

So if you intend to venture into scuba diving, do ensure that you are at a reasonable level of fitness to enjoy the underwater adventure...

1 comment:

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