History of Scuba Diving
Man’s reliance on the sea as a source of food and a means for conducting commerce and warfare dates back to ancient times. While the earliest of swimmers and divers were limited by their inability to breathe underwater for an extended length of time, the use of hollow reeds as a simple type of snorkel facilitated their breathing while submerged. Diving bells came into existence in the 4th century B.C. when divers were let down into the water in a type of cauldron that retained air for breathing. It is believed that the first modern diving bell was used in the early 1500’s. Over the next 300 years, various inventors devised increasingly sophisticated apparatus that served to retain and replenish breathing air so that men would be able to remain underwater for extended periods of time. Included among these inventions were modified diving bells, diving masks, and diving suits. They were all, however, limited in their functionality. Breathing properly and comfortably underwater requires more than simply supplying air for that purpose.
Diving experimenters eventually learned that water exerts ever-increasing pressure on the chest and lungs the further down a diver descends— pressure that is in addition to normal atmospheric pressure. As a result, in order to properly inflate the lungs, the pressure of an inhaled breath needs to counter the ambient pressure virtually exactly. Therefore, if breathing gas is delivered to the diver at ambient levels of pressure and it is correctly regulated, the diver should be able to inhale and exhale without effort regardless of depth. In the early 1800’s, divers were first introduced to the scuba, acronym for self-contained underwater breathing apparatus. The scuba diver carries his own breathing apparatus that provides the gas necessary for breathing, typically compressed air. This allows for greater freedom of movement. Early scuba apparatus allowed divers to remain underwater for a period of time up to one hour.
In 1943, Jacque-Yves Cousteau and Emile Gagnan patented their modern breathing gas demand regulator which became a commercial success. Commonly known as the Aqua-Lung, a name coined by Cousteau, this scuba was the first open-circuit, free-swimming underwater breathing set. It was a twin-hose design, comprised of a high pressure diving cylinder and a diving regulator that provided a supply of breathing gas to the diver at ambient pressure by way of a demand valve. Pressure was regulated in one to three stages on the cylinder itself. In essence, the diver inhaled compressed gas (air) from a tank and then exhaled it into the water adjacent to the tank.
A single-hose 2-stage design set was also developed. With this type, the first stage regulator reduces the pressure at the cylinder and the second stage demand valve regulator delivers the breathing gas at the correct ambient pressure to the diver’s mouth and lungs at the mouthpiece. The single-hose open circuit 2-stage diving regulator coupled to a single pressurized gas cylinder is the most commonly used type of scuba diving equipment today.
In contrast to the open-circuit scuba apparatus, semi-closed circuit and closed circuit designs require the use of a rebreather system in which the air the diver exhales is reprocessed to remove the carbon dioxide, and then reused, or rebreathed, by the diver. While Cousteau experienced oxygen toxicity when using this type of system, modern, more technologically advanced rebreather systems are available today, thanks to the perfecting of the system. These are the second main type of scuba diving apparatus, and are used mostly for technical diving, such as deep sea diving. British, Germans, and Italians adapted oxygen rebreathers for use by their frogmen during World War II. The Americans, specifically USA Major Christian J. Lambertsen, also developed and patented his own series of rebreathers in 1940 and again in 1944. Because they do not cause bubbles and are therefore not visible from the surface, military frogmen in all countries continued to use rebreathers post-World War II. While design details and numbers of cylinders have changed over the years, the scuba diving set remains virtually the same today.
There are many other types of scuba diving beyond the initial diving done by frogmen. With the inventions of the Aqua-Lung and subsequently the wetsuit, the doors were opened for diving to become a recreational activity. In the 1950’s and 1960’s scuba diving equipment was expensive and training very limited. Initially, the only scuba diving training available was for professional diving organizations and the navy. As recreational diving became more popular, however, diving equipment manufacturers began to develop equipment that was more affordable and easier to use, and professional instruction became more widely available.
Today, the types of diving range from recreational and technical to professional. Recreational dives typically do not exceed 100 to 130 feet (30 to 40 meters). Technical diving includes such areas as wreck diving, cave diving, ice diving, deep diving, and usually exceed 130 feet (40 meters). Professional, or commercial divers are employed to perform a job or task underwater. Professional divers can perform civil engineering tasks relating to underwater welding, offshore construction, or oil exploration. Marine activities employ commercial divers to perform such tasks as repair and inspect boats, salvage wrecks, or perform underwater fishing. Other specialized divers include those who work in the military, for the police, as part of a fire department or lifeguard rescue unit, or those who work in areas such as marine biology and underwater photography. Each type requires its own level of training and specialized equipment.
There are many different types of scuba diving equipment, all intended to make diving a safe, efficient, and convenient activity. The basic equipment any diver needs is a scuba set which provides independent underwater breathing with breathing gas, for example an Aqua-Lung or rebreather. This is the diver’s life support equipment.
For thermal protection, divers wear a dry suit if the water temperature is between 32-50°F (0-10°C) or they wear a wet suit in temperatures between 70-77°F (21-25°C). Protective clothing, dive skins, or even a normal bathing suit is worn when water temperatures are very warm, 79-86°F (26-30°C). When determining what to wear while diving, in addition to thermal protection, divers must also consider other factors such as protection from animal stings or environmental abrasion. Other protective equipment includes diving gloves, boots, and hoods. Some divers use safety helmets. Diver’s cages are used in waters where potentially dangerous organisms exist. Shark proof cages, for example, are cages made of extremely tough metal that can withstand ramming by powerful, large sharks. These cages afford scuba divers the opportunity to view dangerous sharks such as the Great White shark up close.
To stabilize a diver’s movements, a backplate and wing device is used to compensate for buoyancy. The cylinder is attached to the backplate, which rests against the diver’s back, and the wing, an inflatable buoyancy bladder, is wedged between the backplate and the cylinder. Some divers use propulsion vehicles to increase their range of movement underwater, weighting systems that help the diver to descend, and fins to propel themselves forward efficiently.
Divers must take constant measurements while underwater, including those that help navigate while submerged. The use of a dive computer and decompression tables helps to ensure the diver avoids decompression sickness. Depending on the diver’s profile, the diving computer will indicate the necessary decompression stops. The computer can also indicate the diver’s depth, the timing and rate of ascent, and levels of oxygen toxicity. For navigating and monitoring depth, specifically the maximum operating depth, divers use a compass and depth gauge, respectively. A diving watch, when used with a depth gauge, helps with monitoring decompression. If underwater visibility is limited or poor, a distance line is used to help guide the diver back to the origination point.
Communication underwater is very important. Unless the diver is wearing a full-face mask, he cannot speak. Instead, divers will communicate via specific hand signals. In fact, regular, two-way hand signal communication during a dive can be critical should problems arise. When one diver signals, his companion should always respond by repeating the signal which indicates acknowledgement and comprehension. There are 10 primary hand signals all divers use. Their intended meanings range from stop to go up or down to distress to danger. Divers may also utilize underwater writing slates and pencils to document observations and to communicate with each other.
In order to see clearly underwater and protect the eyes, divers wear masks. Some masks are full face, offering protection from cold or dirty water. Some divers use diving helmets which, in addition to offering head protection, also provide a secure connection between the gas supply and the diver. Not all diving occurs in crystal blue waters with excellent visibility. Oftentimes dives take place at night or in other environments of darkness or low visibility such as caves or ship wrecks. In these cases, divers utilize torches or flashlights to ensure their safety as well as to communicate both underwater and on the surface.
There are also many tools that are specific to diving. One such tool is a decompression trapeze. This is used in both recreational and technical diving, and it serves to make a diver’s decompression stops safer and more comfortable. A decompression trapeze also provides a visual reference for the diver’s position to the person who is covering the dive on the surface. A diving shot is used where strong tides or low visibility make underwater navigation between the surface and the dive site is difficult. A dive shot consists of a weight and a line connected to a buoy. The weight is dropped at the dive site and the buoy marks the dive site for the people who have remained on the dive boat. Divers can use the line to help control buoyancy and the people in the dive boat use the buoy as a point of reference for where the divers will most likely return to the surface.
Another tool used in scuba diving is a distance line, also known as a guideline or penetration line. This helps divers return safely to their starting point if the diving conditions offer low visibility, water currents, or make piloting difficult, for example in wreck and cave diving. In these cases, the diver must return to open water after completing the penetration but may not be able to determine the return route to the diving ship. The distance line is wound onto a spool or reel, and its length is proportional to the length of line needed for the specific dive. Other miscellaneous tools some divers use include airlifts, dry boxes, lifting bags, net cutters, underwater cameras and housing, and dry boxes.
Equally important is the equipment used by the people in the dive support boat who are monitoring the dive and need to locate divers on the surface during or after a dive. This equipment, referred to as surface detection aids, also serve to mark a diver’s position during drift diving or at a decompression stop, and to help rescue services if necessary to locate a diver. Surface detection aids include marker buoys, red and yellow collapsible flags, flashlights, strobe lights, whistles, flares, orange water dye, and reflective material such as a mirror or compact disc.
Surface equipment serves multiple purposes. Diving air compressors are used to fill the diving cylinders with the high pressure air or other gasses that will be used during a dive. A dive boat will fly a diver down flag to indicate to others that divers are underwater in a particular area. A global positioning system (GPS) is used to locate specific dive sites while a SONAR is used to measure the depth and profile of a dive site.
For those interested in learning how to scuba dive, courses are available in many locations. An Open Water Diver course is the most common and takes at least three days to complete. This course provides a full introduction to scuba diving, and the people who successfully complete it receive certification which allows them to go on to take more advanced training. Divers should generally be in good overall health and able to meet diving fitness and swimming requirements. Equipment is usually available for students to rent for the duration of their dive course. Upon completion, the newly trained diver will then be able to buy his or her own alternate air source, buoyancy control device, fins, cylinder, depth gauge, and more, tailoring specific dive equipment to ensure it aligns well with the type of diving the user expects to be doing.
