Deep_diving

The meaning of the term deep diving is defined by the level of the diver\'s diver training, diving equipment, breathing gas, and surface support:

• in recreational diving, 30 metres / 100 feet may be a "deep dive"
• in technical diving, 60 metres / 200 feet may be a "deep dive"
• in surface supplied diving, 100 metres / 330 feet may be a "deep dive"

Deep diving has had many different labels of certain depths, but the real importance is how much experience and how much training you have had. For a beginning open water diver sixty feet is an extreme depth and it is necessary to have additional training. Another important point is to not push yourself to achieving a certain depth. If you are going on a “deep dive” it is necessary to know why you are diving. This helps to increase discipline and to decrease the possibility of accident and confusion. When deep diving it is essential for psychological and physiological fitness. When traveling deeper there are many different obstacles that could affect the dive. The issue of temperature and lighting make the physical and psychological wellness essential. It is easy to get disoriented in the depths so being able to keep a level head is important. The pressure demands good physical conditioning. There also times that may require increased stamina. Along with lack of light and warmth there are also the possibilities of currents and visibility.

There are particular problems associated with deep dives:

Deep diving obviously has more consequences and dangers than basic open water diving. Nitrogen narcosis, or the “narks” or “rapture of the deep”, starts with feelings of euphoria and over-confidence but then lead to numbness and memory impairment similar to alcohol intoxication. Decompression sickness, or the “bends”, is when the gas bubbles of nitrogen get caught in the joints on an ascent. Yet, the effects tend to be delayed until reaching the surface. Bone degeneration is caused by the bubbles forming inside the bones; most commonly the upper arm and the thighs. Air embolism causes loss of consciousness and speech and visual problems. This tends to be life threatening, but sometimes the symptoms resolve before the recompression chamber are needed. All these are harms and possibly worse effects of deep diving.

• High gas consumption. Gas consumption is proportional to pressure - so at 50 metres / 165 feet (6 bar) a diver breathes 6 times as much as on the surface (1 bar). Heavy physical exertion causes even more gas to be breathed.
• Increased nitrogen narcosis. This causes stress and inefficient thinking in the diver. When breathing air many divers find 40 metres / 130 feet a safe maximum depth.
• The need to do decompression stops increases with depth. A diver at 6 metres may be able to dive for many hours without needing to do decompression stops. At depths greater than 40 metres / 130 feet, a diver may have only a few minutes at the deepest part of the dive before decompression stops are needed. In the event of an emergency the diver cannot make an immediate ascent to the surface without risking decompression sickness. The diver needs a disciplined approach to planning and conducting dives and needs to carry extra gas for the decompression stops to reduce the risk of being unable to complete the stops.
• Drifting. If long decompression stops are carried out in a tidal current, the divers may drift away from their boat cover or a safe exit point on the shore.
• Increased breathing effort. Gas becomes denser and the effort required to breathe increases with depth.
• Increasing risk of carbon dioxide poisoning.

Deep diving also requires some different equipment than if you were just shallow or surface diving. For example, a watch is crucial so that the diver can keep up and stay within the limits of the planned dive and count the decompression times. Weights are also very necessary when deep diving to hold position for decompression and also to stay at the bottom for the needed length of time.

• Oxygen toxicity

There are several solutions to these problems:

• Carry larger volumes of breathing gas to compensate for the increased gas consumption and decompression stops.
• Rebreathers are much more efficient consumers of gas than open circuit scuba.
• Use helium-based breathing gases such as trimix to reduce nitrogen narcosis and stay beyond the limits of oxygen toxicity.
• A diving shot, a decompression trapeze or a decompression buoy can help divers return to their surface safety cover at the end of a dive.

Sources

Gleason, Bill. (1994, October). Technical or Recreational. Los Angeles, 43 (10), 6.

Scully, Thecla. (2007, August 17-24) Allure of the Underwater World and Awful Ailments of the Deep. Irish Medical Times, 41 (33), 60.

Graver, Dennis and Robert Wohlers. (1984). PADI Advanced Diver Manual. PADI, 177-208.

External links

• Recreational Deep Diving

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