Archive for November, 2005

World War II provided the incentive for rapid strides in the development of scuba. In September, 1941, Italian Navy

The modern scuba diver goes to sea with a full load of equipment. In addition to the basic breathing apparatus, undersea hunting weapons and photographic equipment add new dimensions to the sport.

scuba divers dramatically demonstrated its importance and potential military value when they carried out a successful attack against a British tanker at Gibraltar. This attack and others that followed did much to give the United States and British Navies an interest in developing scuba and training scuba divers.

However, the attempts to develop a scuba system go far back in time. There are many reports of different primitive tribes whose divers went under water with inflated bladders full of air which provided an underwater air supply. Man’s first self-contained recirculating diving apparatus is probably the equipment designed in 1680 by Giovanni Borelli, an Italian astronomer and mathematician. Crude by any modern standards, his equipment demonstrated man’s desire to be able to dive free of encumbrances and independent of a surface supply of air.

The apparatus consisted of a large air bag which fitted over the diver’s head. It had a single glass port for vision. Air circulated through a tube running outside, through a smaller bag intended to trap moisture, and back into the air bag. Borelli believed that water cooling would remove impurities from the exhaled air, making it suitable for rebreathing. In order to help the diver regulate his displacement in water, the apparatus also had a complicated cylinder and piston displacement. Although this equipment did not work, it foreshadowed later closed-circuit scuba.

A great stride toward modern scuba came in 1825, when W. H. James, an Englishman, designed a self-contained diving suit incorporating a supply of compressed air contained in an iron reservoir worn about the waist. Unfortunately, this equipment aroused little interest and was not considered important at the time, but this suit was the first to incorporate a supply of compressed air. In 1866, Benoit Rouquayrol of France patented the first satisfactory regulator for open-circuit scuba. This device constituted a milestone in man’s work toward freedom and mobility beneath the sea. The drawback to his equipment, however, was the lack of a suitable supply of high-pressure air such as we have today. As a result, his equipment was developed into a surface-supplied diving suit, and the development of true scuba had to wait.

Then, in 1878, H. A. Fleuss of the British firm, Siebe-Gorman & Co., designed a workable closed-circuit oxygen rebreathing scuba. The unit utilized a solution of caustic potash to remove carbon dioxide from the exhausted gases. In 1902 Fleuss improved the unit in collaboration with Sir Robert H. Davis. This apparatus was the prototype of modern submarine-escape appliances and the forerunner of modern closed-circuit scuba.

Borelli’s design

James’s design

By late 1940, the Americans were in the field of scuba development. In that year, Christian J. Lambertsen developed and demonstrated his oxygen-rebreathing scuba the LARU (Lambertsen Amphibious Respiratory Unit). This device was first adopted by the Office of Strategic Services, and early in 1942 the first American scuba divers were in training. The same unit was later adopted by our Underwater Demolition Teams for use in operations requiring stealth.

THE exploits of TV scuba divers have done much to spur interest in underwater swimming as a participant sport, although “self-contained diving” has been gaining momentum rapidly among water sports since World War II when stories of the activities of military “Frogmen” were released and the equipment became available for civilian use.

The word “scuba,” which has become part of the language of water sports in recent years, refers to “self-contained underwater breathing apparatus,” or diving using a tank (or tanks) of compressed air strapped to the back, a connecting hose, face mask and nippers. Scuba equipment enables a swimmer to remain under water for varying lengths of time, limited by tank volume and the depth of the dive.

Obviously there is some inherent danger in scuba diving. Because so many persons have ventured into this new activity without the proper skill or supervised instruction and practice, there have been a number of accidents and fatalities. In some areas restrictive legislation has been adopted prohibiting scuba diving or limiting it to certain areas, or requiring certain safety precautions and the display of the skin-diver’s flag where diving is being practiced.

The Boy Scouts of America have adopted a general policy that scuba equipment should not be used in scouting under any conditions except in an emergency, and then only by experts. Most experts in the field of aquatic sports agree that only persons eighteen years of age or over should be encouraged to go into scuba diving, and that a long period of training, conditioning and practice under a qualified and certified expert is basic preparation for the sport.

Skill Requirements for Skin Diving

The Boy Scouts of America have established a set of skill performances for skin diving that might well be adopted by any skin-divers’ club or by a parent as minimum standards before allowing free use of skin-diving equipment. The B.S.A. requirements state:

1. Enter water feetfirst, holding mask in hand. Attach mask to face and swim on surface for 20 feet, holding breath.
2. Tread water with fins for 2 minutes.
3. Swim 200 yards with fins, using frog, scissors and flutter kicks.
4. With snorkel adjusted, swim for 3 minutes slowly on surface, breathing through tube.
5. Surface dive with fins and mask in 8-10 feet of water and retrieve a 2-pound object.
6. Surface dive with fins and mask in 8 feet of water 5 times in succession, with brief rest intervals on float between dives.
7. Locate brightly colored underwater object from surface, dive and retrieve same.

A float or buoy should be used by every individual or group of skin divers. An inflated rubber inner tube painted yellow is highly visible and serves as a resting place, an assembly point, and emergency buoy. The tube should be anchored. In large-group skin diving, one such float should be provided for every 4 divers.

The skin diver’s warning flag has been recognized by the boating laws of many states and in Canada. It is a red flag with a diagonal white band, flying from any floating object. The flag signifies to boatmen that a skin diver is in the general area. Boats are required to avoid the area, or if they must pass through it, to do so at very reduced speeds and to keep a sharp lookout to avoid swimmers, floating objects, or passing through air bubbles. Skin divers are required by law to display the flag in some areas.

Hyperventilation-the practice of taking several deep breaths before swimming under water can endanger life. Repeated deep breathing will not provide the diver with an additional supply of usable air. Instead, this type of breathing may cause a swimmer to become dizzy or even unconscious after submersion. Another effect of hyperventilation is that it seems to turn off the body’s built-in safety regulators which normally indicate when it is necessary to come up for air.

The basic safety practices for skin diving are:

-> Have your general physical condition checked by a physician before undertaking skin diving.
-> Know the area where you are diving. Avoid murky water or diving amid pilings or other obstacles.
-> Never dive alone.
-> Avoid fatigue or chill from too long periods of diving.
-> Always use a float with line and diver’s flag.
-> Always enter water feetfirst.
-> Do not swim under water for long distances or periods of time.
-> Do not skin dive in rivers with strong currents or in ocean inlets.
-> Avoid diving in boat channels or where there is any boat traffic.
-> Always look up when surfacing.