Recreational SCUBA Diving: An Overview

• What does SCUBA stand for?
• How popular is SCUBA Diving?
• What makes up SCUBA equipment?
• What is SCUBA certification?
• Who teaches SCUBA?
• How does recreational SCUBA diving differ from other forms of SCUBA?
• What is DAN?
• The realm of Technical Diving
• What is the buddy system?
• Why is 130 feet the maximum depth in recreational diving?
• What is mandatory decompression and why is it not a part of recreational SCUBA Diving?
• How can I learn more about SCUBA?

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WHAT DOES 'SCUBA' STAND FOR?

SCUBA is an acronym that stands for 'self-contained underwater breathing apparatus'. There are several ways one can go under water (breath-hold, helmet diving, submarine, etc.). when you are "Diving with SCUBA" this indicates that you are using equipment that is completely carried by the diver and not connected to the surface, hence self-contained.

 

HOW POPULAR IS SCUBA DIVING?

An estimated 2.5-3.5 million Americans participate in recreational SCUBA diving. Another 500 thousand become certified each year in the United States. In the early days of SCUBA diving (roughly 1950-1970), participants were predominately young men. Today the sport is enjoyed by people in all age groups and both sexes. And why not? Just about any teenager or adult who enjoys the water and can swim, and who does not have heart or lung impairment, can learn to SCUBA dive. It does not take great physical strength or unusual exercise tolerance. All it takes is the desire, plus some basic classroom and in-water training.

SCUBA originally began with military and commercial applications, where it is still employed. However, by far its widest use, in terms of number of participants, is recreational. Recreational SCUBA today is like other any other sport that requires specialized equipment and training, such as snow skiing, sailing, mountain climbing and horseback riding. Here we are trying to provide an overview of recreational SCUBA diving, and explain how it differs from other forms of diving with SCUBA equipment.

 

WHAT MAKES UP SCUBA EQUIPMENT?

SCUBA apparatus for the recreational diver consists of:

• a tank of compressed air carried by the diver on his or her back.
• a first stage regulator attached to the tank that serves to lower air pressure delivered to the diver.
• a second stage demand regulator and mouthpiece, that delivers air on inhalation and closes on exhalation.
• a face mask that covers the diver's eyes and nose, to allow for both underwater vision and equalization of air pressure within the mask.
• an extra second stage regulator and mouthpiece, carried by the diver in case of emergency (when attached to a long hose, this extra second stage is called an octopus).
• two submersible gauges, one to display an accurate depth and the other to show how much air remains in the tank (or, alternatively, a single gauge that combines both functions, e.g., as part of a dive computer).
• an inflatable vest (buoyancy compensator, BC) worn to provide a means of establishing positive buoyancy when needed.
• a weight belt and weights (or some other type of weight system), worn to compensate for the positive buoyancy of the diver and SCUBA apparatus.
• fins to facilitate self-propulsion in the water.
• a wet suit or other type of body protection to prevent hypothermia (and secondarily to prevent cuts and abrasions under water); in cold water gloves and a hood may be worn for hypothermia protection also.

Optional equipment for SCUBA diving numbers many items, such as a snorkel, dive knife, small tank of extra air, gloves, dive computer, compass, dive lights, writing slate, whistle, and inflatable signaling device. Depending on the circumstances (e.g., lights for night diving, a snorkel for surface swimming) some of these items may at times be essential, but they are not part of basic SCUBA equipment.

With the basic SCUBA equipment a qualified diver can safely remain underwater for anywhere from a few minutes to over two hours; the time limit for any given dive will depend on the depth of that dive, the rate of air consumption, and the profile of any dives made within the previous 6-12 hours.

 

WHAT IS SCUBA CERTIFICATION?

Potential hazards that every SCUBA diver must be aware of include de-compression sickness, air embolism, hypothermia, physical exhaustion, injuries from marine life, boating accidents, sunburn, and out-of-air catastrophes. Despite the list of potential problems, recreational diving is actually a safe sport if the diver is healthy and trained properly, each dive is carefully planned and dive limits are followed. The most serious problems, and how to avoid them, are covered in an entry level SCUBA course.

The entry level course, also known as 'basic open water' or 'basic certification,' takes about 30 hours. About 10 hours is spent in classroom instruction and the remainder in supervised pool and open water diving. 'Open water' means a natural body of water open to the sky. Upon completion, a certification or 'C' card is issued. The C card contains the new diver's picture, date of course completion and signature of the instructor. The basic open water course is fairly standard and is given under the auspices of one of several national training agencies.

Many people are first exposed to SCUBA through the "resort course." This is an introductory lesson offered at a resort or on a cruise, and is always taught by an instructor (i.e., one who is also qualified to teach the standard open water course). The resort course is highly variable; it may include only a brief lecture on a crowded bus on the way to the dive site, or a leisurely morning pool session before the afternoon open water dive (I have seen both methods). Because the resort course contains no textbook and very little in the way of theory or skills testing, it does not certify for independent diving. It is also good only for that resort and for the time you are a guest there. If you return six months or a year later to the same resort you would have to start all over with another resort course. (One exception is the Club Med resort course, which offers 'Club Med Certification'. The student completing a Club Med resort course can dive at any other Club Med around the world, but always with a Club Med instructor and after an initial checkout dive.)

Resort courses are fine for introduction to SCUBA, but anyone who has enjoyed the experience is encouraged to take a standard certification course and learn the necessary skills and theory. Standard certification is also more practical. The C card allows one to rent or buy SCUBA equipment anywhere in the world, and to engage in recreational diving without supervision by an instructor. The Standard certification is also a mandatory requirement for anyone wanting to join and participate in the diving activities with the Scuba Club at the University of South Carolina.

The certification process distinguishes recreational SCUBA diving from most other sports that use specialized equipment (e.g., snow skiing, mountain climbing). Without a C card (i.e., without certification) one should not go SCUBA diving (unless accompanied by a professional SCUBA instructor).

 

WHO TEACHES SCUBA?

In college the lowest academic rank is the "instructor," usually someone in graduate school who is assigned to teach and work under a "professor." In the world of SCUBA the instructor is the highest level. A SCUBA instructor is the only person trained and qualified to teach SCUBA diving. He or she works under the auspices of a national SCUBA training agencies. The SCUBA instructor can be assisted by other SCUBA professionals who are in training to become a SCUBA instructor; they may have the title of dive master (the entry level position for a SCUBA professional) or assistant instructor. However, only someone with instructor status can teach the basic open water course.

The SCUBA Club at the University of South Carolina alo provides facilities and training for Club members to become certified in several aspects of SCUBA Diving including the Basic Open Water certification. For more information about what is available in terms of certification and training please contact us at scuba@gwm.sc.edu.

 

HOW DOES RECREATIONAL SCUBA DIVING DIFFER FROM OTHER FORMS OF SCUBA DIVING?

Diving was revolutionized by the development of a workable demand regulator, co-invented in 1943 by Jacques Cousteau and Emil Gagnan. The "sport" of SCUBA diving did not catch on for another 10 years. Today the greatest use of SCUBA equipment is for recreational diving. Recreational SCUBA diving, as taught by national certifying agencies, is defined as diving that:

• Uses only compressed air as the breathing mixture.
• Is never done solo.
• Does not exceed a depth of 130 feet.
• Has a depth-time profile not requiring a decompression stop; if necessary one can ascend to the surface without stopping.
• Does not require specialized training beyond the basic open water course.
• SCUBA equipment is also widely employed by two other types of divers, loosely categorized as "professional" and "technical." By definition, these two groups are not constrained by the RSD criteria listed above.

Professional diving is done for military, governmental, commercial, or scientific purposes. Professional divers are paid to dive. They have a specific mission for each dive, e.g., lay a mine or recover a bomb (military), look for a body or a weapon (law enforcement agency), explore for oil (commercial), map an ancient wreck or examine a new species of fish (scientific).

Technical diving is the term for all diving that exceeds recreational limits but is not engaged in for profit. Although many, if not most, technical divers consider themselves involved in a recreational activity, the nature of their diving and type of equipment used exceed the boundaries of RSD. To be sure, there is not universal agreement on what constitutes technical diving, and any attempt to define it tends to degenerate into heated discussion and semantics. For the novice or basic open water diver, the following activities can be considered to be "technical diving."

 

WHAT IS DAN?

DAN is a unique organization dedicated to safety, education and research in the scuba diving community. Divers Alert Network was founded in 1980 at Duke University Medical Center as recreational scuba diving's 24-hour emergency hotline for injured divers.

Today, the nonprofit organization is an international dive safety leader supported by the largest association of divers in the world.

DAN provides important services to divers and dive travelers, including the following:

• 24-hour Diving Emergency Hotline
• 9-to-5 Medical Information Line
• Recompression Chamber Assistance program
• Oxygen Provider courses
• Dive Safety Research studies
• Educational seminars

DAN member benefits include:

• Dive accident insurance eligibility
• Access to emergency medical evacuation
• Subscription to Alert Diver, DAN's award-winning bimonthly magazine
• Dive & Travel Medical Guide
• Exclusive DAN Tag (tm) purchasing privileges
• Click here to view more information about the benefits DAN provides to their members.

 

THE REALM OF TECHNICAL DIVING

• cave diving
• ice diving
• very deep diving (to greater than 130 feet)
• mixed gas diving (using gas mixtures other than air, such as nitrox or trimix)
• deep-penetration wreck diving
• diving with specialized life-support equipment (e.g., O2 re-breathers)

Much of technical diving is taught by agencies other than the national open water certification agencies. However, recently PADI and other national agencies became involved in nitrox certification, although the activity is still not considered part of basic open 'recreational diving.' Still, the trend is to expand the envelope of technology to encompass more and more divers, and it is conceivable that some of today's advanced technology (e.g., rebreathers)will one day be routinely used by open water recreational divers. Clearly, the distinction between 'technical' and 'recreational diving' is becoming less distinct over time. (No matter how diving activities are classified, no one should engage in any diving activity unless certified in that activity or else supervised by a qualified instructor.)

 

WHAT IS THE BUDDY SYSTEM?

RSD requires that each diver be accompanied under water by a buddy who can share air or provide other assistance. SCUBA apparatus is designed to carry an extra demand regulator. This is required in case one diver runs out of air and has to share a single tank with his or her buddy. Ideally, the buddies should have similar training and skill levels; it does no good to have a buddy who dives deeper or stays down longer than you do. Buddies should stay close together and always be aware of each other's location.

 

WHY IS 130 FEET THE MAXIMUM DEPTH IN RECREATIONAL DIVING?

The 130 foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave navy divers about 10 minutes of bottom time on compressed air; going any deeper on air made no sense to the Navy because the time available to do useful work was simply too short. As with many diving issues in the early days of SCUBA (e.g., the 'no decompression' limits), the Navy standard was also adopted by the recreational training agencies.

Some experienced recreational divers do go deeper than 130 feet, and yet still stay within no decompression limits. However, since the risks of decompression illness, running out of air, and nitrogen narcosis increase as you go deeper, the training agencies feel that some arbitrary limit must be set and have stayed with 130 feet. Thus, although one can dive deeper and stay within no decompression limits, diving deeper than 130 feet a) is not taught by the recreational training agencies, and b) must be undertaken with great care and an understanding of the increased risks.

 

WHAT IS MANDATORY DECOMPRESSION AND WHY IS IT NOT PART OF RECREATIONAL SCUBA DIVING?

"Decompression" always occurs when we go from a higher to a lower ambient pressure. Thus all compressed gas diving is decompression diving. When recreational diving is referred to as "no decompression diving" it really means "no mandatory decompression stop diving." A decompression stop should never be necessary within the guidelines of RSD.

A decompression stop is often necessary in dives deeper or longer than allowed in RSD; it provides time for some of the excess nitrogen that entered the tissues to "gas off" (diffuse into the blood stream and then be ventilated out by the lungs), thereby minimizing risk of decompression sickness (DCS). Based on experiments, plus much trial and error experience, the amount of excess nitrogen remaining in the tissues after a planned, mandatory decompression stop should not cause DCS.

Since professional and technical divers often spend longer periods under water and/or dive deeper than recreational divers, they must know when to stop on ascent and how long to wait before surfacing. By contrast, each recreational dive is planned so that the diver can ascend continuously to the surface without encountering decompression sickness; the diver is still decompressing on the way up, but doesn't have to stop to allow further decompression. The basic assumption is that diving is inherently made safer by avoiding dives that require decompression stops. This is both the philosophy and practice of recreational diving today.

The "no decompression stop" limits in RSD are based on maximum depth, time under water, and extent of any preceding dives, all factors which directly affect tissue nitrogen uptake. The limits are set in dive tables known to every certified diver, and are incorporated into all dive computers.

Excess nitrogen, which enters tissues due to the increased ambient pressure under water, determines the "no-decompression stop" limits. A non-repetitive dive (no previous dive within a specified time period, typically 6-12 hours) to 130 feet has an allowable "actual bottom time" (measured from the time dive commences to start of ascent) of only about 5-10 minutes for a dive to 130 feet. Beyond this brief time span the diver risks developing decompression sickness from a continuous ascent. In contrast, at 35 feet, on a non-repetitive dive, the 'no decompression' bottom time is about 205 minutes.

Although RSD is always planned for no decompression stop required, it is routine practice to make a 3 to 5 minute "safety stop" at 15 feet before surfacing from any dive deeper than about 40 feet. This is a decompression stop but it is not mandatory, just added for extra safety to the dive; hence the term safety stop. In theory, when adhering to the recreational diving tables one should not experience DCS if a safety stop is not made. Nonetheless, all dives deeper than about 40 feet should incorporate a safety stop, and it is univerSally Grinton practiced. If any dive requires a decompression stop for any reason, it has exceeded the limits of recreational diving.

 

HOW CAN I LEARN MORE ABOUT SCUBA?

The are several commercial agencies and organizations that provide training and study in the sport of SCUBA Diving. Usually, these agencies can be contacted by looking up your local dive shop whom are usually a qualified agency for instrucution and certification.

The SCUBA Club at the University of South Carolina alo provides facilities and training for Club members to become certified in several aspects of SCUBA Diving including the Basic Open Water certification. For more information about what is available in terms of certification and training please contact us at scuba@gwm.sc.edu.