Buddy diving is the use of the buddy system by scuba divers. It is a set of safety procedures intended to improve the chances of avoiding or surviving accidents in or under water by having divers dive in a group of two or sometimes three. When using the buddy system, members of the group dive together and co-operate with each other, so that they can help or rescue each other in the event of an emergency. [1] This is most effective if both divers are competent in all relevant skills and sufficiently aware of the situation that they can respond in time, which is a matter of both attitude and competence. [2]
In recreational diving, a pair of divers is usually considered best for buddy diving. With threesomes, one diver can easily lose the attention of the other two, and groups of more than three divers are not using the buddy system. The system is likely to be effective in mitigating out-of-air emergencies, non-diving medical emergencies and entrapment in ropes or nets. When used with the buddy check it can help avoid the omission, misuse and failure of diving equipment.
The buddy system is the situation which occurs when two divers of similar interest and equal experience and ability share a dive, continuously monitoring each other throughout the entry, the dive and the exit, and remaining within such distance that they could render immediate assistance to each other if required. [1]
— Bob Halstead, Line dancing and the buddy system
In technical diving activities such as cave diving, threesomes are considered an acceptable practice. [3] This is usually referred to as team diving to distinguish it from buddy diving in pairs.
When professional divers dive as buddy pairs their responsibility to each other is specified as part of standard operating procedures, code of practice or governing legislation.
Buddy diving is intended to enhance the safety of scuba diving by having two or three competent divers acting as safety divers for each other during a dive in conditions that are within their capabilities, and using equipment that is familiar to all team members. In principle, each diver is capable of rendering assistance to the other in any reasonably foreseeable contingency, and willing to do so within the scope of acceptable personal risk. [4] The buddy divers are expected to take mutual responsibility for the safety of the buddy pair above and below the water, and this responsibility commences when the divers prepare for the dive. It is assumed that it is unlikely that both divers will experience the same problem at the same time, allowing the diver not in trouble to assist when the other diver has difficulties. [4] [5] This mutual responsibility is usually not required by legislation, is entirely voluntary unless required by terms of service of a service provider, and generally cannot be enforced.
This purpose is theoretically fulfilled by the buddy assisting the diver to kit up, checking that the diver's equipment is correctly assembled and mounted, assisting the diver into the water where appropriate, checking for leaks, monitoring gas usage, providing an alternate breathing gas supply in case of an emergency, performing a rescue if the diver is unable to manage an emergency, and assisting the diver out of the water after the dive if appropriate. [4] This system can mitigate high-risk emergencies when performed to the standards. This is not a controversial issue. This level of assistance requires the buddy to be familiar with the diver's equipment in detail, including the adjustment of harness and emergency release of weighting systems, control of inflation and dump valves, siting and attachment of secondary demand valve, knife and any other safety equipment. Recreational divers may be trained in some or all of these skills depending on their certification. [4] The buddy system is not considered sufficient on its own. Dive planning, medical and physical fitness to dive, suitable and correctly functioning equipment, appropriate surface support, skills, experience and knowledge are all part of the diving safety system. [4] To be fully effective, the buddy system is applied to an agreed dive plan, with effective communications, the willingness and ability to assist each other in all reasonably foreseeable circumstances associated with the dive plan, and the will to follow the dive plan. [4] [5]
For the buddy system to function effectively, each buddy must be sufficiently competent to provide the required service, and be present when it is needed. Several conditions must exist for the buddy system to succeed:
Most recreational divers never advance to a high level of competency as might be indicated by certification and experience, and furthermore, many divers do not dive sufficiently frequently to maintain their skills. [7] Nevertheless, they are routinely expected to provide assistance to their dive buddies in the event of an emergency, and are also routinely allocated to dive with complete strangers who may be using unfamiliar equipment. It is standard practice for many, if not most diving charter organisations to allocate buddy pairs among divers they have never assessed for competence on the basis of their certification and claimed experience. Optimal conditions are seldom encountered on open-water recreational dives. [2]
The three alternatives, solo diving, diving in teams of three, and diving as an individual in a large group, may have disadvantages when compared to the buddy system, especially for the novice:
Scuba diving has roots in the many small and enthusiastic snorkelling and spearfishing clubs in the decades just before and after the Second World War. [10] After the invention of the "aqualung" by Cousteau and Gagnan, the first commercially manufactured underwater breathing apparatus became available for sale for recreational purposes in the late 1940s. As the new sport of scuba diving rapidly expanded through the 1950s, several organisations—notably the YMCA—began programmes to train swimming enthusiasts in this new aquatic pastime, and began to codify what they believed were proper practises for this expanding sport. [11] The YMCA considered the buddy system a useful corollary to the "never swim alone" rule of their swimming and lifesaving programmes. Cousteau himself independently implemented a buddy system from the earliest days of exploratory diving after a number of harrowing diving incidents. [12] The buddy system did have some useful aspects: cross checking of equipment before dives, facilitating assistance for possible entanglement problems or equipment failures, and enhancement of the social nature of diving. The YMCA remained a major force in the development of diver certification for the first 50 years of the sport. When these programmes were adopted by the emerging scuba certification agencies such as NAUI, PADI, and BS-AC, buddy diving developed into one of the two most widely known rules of the activity: "Never hold your breath," and "Never dive alone." [13]
The official terminology of recreational diving defines only the two extremes: buddy/team diving, and solo diving. In practice, many dives are somewhere between these extremes, in a continuum with some informal descriptors, and many behaviours deviate from the buddy diving standard.[ citation needed ]
Opinions differ in how best to form buddy teams among a group of divers. One school of thought holds that buddies should always be closely matched in skills, experience, and interests so that one diver does not hold back the other in achieving an enjoyable dive. [5] This becomes particularly true when a diver is on an especially expensive or unique diving trip or holiday. This is a suitable arrangement for purely recreational dives. The problem with this approach is that it also pairs up inexperience – which can be dangerous if a diving emergency arises (fortunately, this is not statistically very often).[ citation needed ] The alternative is to buddy-up a more experienced diver with a less experienced buddy to counter this "experience gap". This also helps to advance diving skills by having one buddy essentially act as a tutor. The British Sub Aqua Club strongly encourages and practices this approach, which is appropriate in a club environment where non-instructing members assist in post-certification training. [14] The problems with this system, are that they may limit the more experienced diver's opportunity to dive as he would have wished, and that the less experienced diver is not an ideal buddy to the more experienced diver, who must take an unbalanced share of responsibility, and this constitutes an informal training scenario. Compatibility problems are magnified when divers who do not know one another are paired off as buddies by the dive operator. [15] [5] Numerous harrowing stories abound about diving with "the tail-end-Charlie" or the "buddy from hell" out of such practices. [16] The "perfect buddy" is a long term friend or acquaintance, a partner who matches one's own high level of diving skills, who has the same interests, the same stamina and fitness, and who enjoys the companionship in sharing enjoyable diving. [17] Although the principal reason for instituting the buddy system is the mitigation of the risks in diving, the sharing of diving experiences and the enjoyment of being paired together with a friend, family member, or keen fellow enthusiast while on a dive ranks very highly in the reasons many divers enjoy the recreation of scuba diving. [5]
The buddy system is expected to provide a level of redundancy within the pair of divers, as a safety backup in case of any equipment failure. Within the overall buddy pair almost all equipment can be seen as part of a combined "redundant system": two tanks, two depth gauges/ dive computers, two lights, two knives or line-cutters, – even two brains. During the dive, measurement instruments (gauges, dive computers, compass, etc.) are available to cross-check one another, a second set of life support equipment (i.e. gas supply) is there as a backup in case of a failure in one of the divers' systems. Sometimes a single special-purpose but non-critical piece of equipment is shared by the buddy team, like a single deployable surface marker buoy on which to ascend and mark the team’s position or a single underwater metal detector. For the system to work effectively, a buddy team must have a shared and agreed dive plan, and both divers must accept the responsibilities of executing it. [18] The plan will specify the basic parameters of the dive such as maximum depth, route, duration, critical breathing gas pressures and decompression plan, who will lead and who follows, buddy separation procedures, etc. and the dive objectives: is it general sightseeing, to view a wreck, photography, hunting a type of game?. In technical diving, these objectives often become much more complex and very specific – penetration of a particular part of a cave to a particular point. Many diving objectives require allocation of specific roles and responsibilities. For example, in lobster hunting on the west coast of America, buddy teams often split into assigned roles of hunter-game catcher, and stower-catchbag carrier, and overall dive success depends on teamwork and carrying out assigned roles. [19] [5]
An important aspect of the buddy function is providing breathing gas in an out of air (OOA) emergency. This can happen in the event of a regulator failure or using up most of the breathing gas while inattentive, distracted, or dealing with an urgent problem. Part of an effective buddy system is preventing and avoiding out of air emergencies by effective gas management, and effectively managing emergencies when they do occur in spite of diligent monitoring. [20]
In the early years of scuba, each diver carried a single second-stage regulator, and in the case of an out of air emergency, the buddy pair made an emergency ascent to the surface while the two divers took turns buddy breathing from the mouthpiece of remaining functional scuba set. [21] Though this system worked effectively enough in a swimming pool or in open water practice sessions, and sometimes worked for skilled and disciplined divers in actual emergencies, in some cases stress and physical difficulties made it fail.[ citation needed ]
To simplify the procedure for air sharing, the recreational diving industry moved to a configuration that provided each diver an additional second-stage regulator, as a backup to the primary. The backup is known variously as the octopus stage, backup, secondary, or (obsolescent) safe second. The term octopus came about because several regulator and other hoses hanging from the first stage made the unit look a bit like an octopus. [22] Two general systems have evolved for carrying and deploying the backup demand valve—one more prevalent in recreational diving and the other commonly found in technical diving (although some crossover exists). In both systems, each diver carries two demand valves. They may be attached to the first-stage regulator of a single tank or to two first stage regulators of twin cylinders. The primary regulator is for normal breathing during the dive, and the secondary regulator ("octopus") is a backup for oneself or an out-of-air buddy.[ citation needed ]
Two basic procedures are in common use: Donating the primary and donating the octopus.
A system recommended by some organisations, mostly those involved in technical diving (GUE, [23] CMAS-ISA, other tech and cave diving groups) is to equip the regulator normally used throughout the dive (the "primary") with a long hose, typically 1.5 to 2 metres (5 to 7 ft) long, proportional to the height of the diver. This is the regulator that is donated to a diver who is out of air. The "secondary" or "backup" regulator is then reserved for the donor diver and is on a short hose, suspended just under the chin by a "necklace" that can break free in an emergency. The principal advantage is that the diver who is in trouble receives a regulator that is known to be working and provides breathing gas appropriate for the current depth—and quite possibly gets air more quickly than if the clipped off octopus were donated. Donation of the long hose is particularly beneficial for cave and wreck penetration diving where divers sharing air may need to pass through small openings, as the hose length lets them swim in single file where necessary. The length of the hose also allows the divers to swim side-by-side or one above the other in all possible arrangements. Another advantage is that the secondary regulator stows out of the way, protected from strong water flow, contamination and snags, and where the diver can notice if it leaks—but remains accessible without requiring the use of hands, as divers can pick up the mouthpiece by dipping their chin. [24] [25] This arrangement is slightly more cumbersome to use and requires greater skill to wear, deploy and recover. Benefits may not outweigh disadvantages for open water divers in relatively low hazard conditions. [26] [27]
The octopus is usually clearly marked, the convention is a yellow hose and yellow second stage though a luminescent green is sometimes favoured. Many dive equipment manufacturers provide secondary regulators marked exactly to this standard and "tune" them specifically to the role of octopus. The octopus second stage is usually stowed in an easily located, accessible position and is easily detachable from the device that holds it. Most recreational agencies recommend or specify [28] [29] that this position be in the "Golden Triangle" drawn between a divers chin and nipples. [30] The octopus hose is usually made long enough (1.2 metres (4 ft)) so that the divers are not inconveniently crowded against one another when the octopus regulator is in use. The procedure to provide the octopus is that the donor diver hands over the octopus [31] —but if a buddy does not notice the buddy’s distress, the out-of-air diver has been taught to take the stowed octopus. An advantage with this method is that donor handover is consistent in both octopus handover and for handover of any independent bailout device such as a removable pony bottle. As part of pre-dive checks, the team should review the procedure for handing-over or accessing the octopus in out-of-air emergency. In recreational diving, if good gas management practice has been followed, either buddy should have sufficient air for both to safely ascend to the surface, even if the emergency occurs at the end of the dive. This may not be the case where an unplanned decompression obligation exists. [32]
It is helpful if divers wear their equipment in a way that follows standardised conventions so that buddy partners know where to access that equipment if called on to assist their buddy. As there are several conventions, and divers who do not follow locally popular conventions, it is important for divers planning to dive as buddies to familiarise themselves with the configuration used by the other in the pre-dive checks. [5]
Diving takes place in what Cousteau called "The Silent World." The relative silence of the sea is one of the enjoyable aspects of scuba diving, but does not help foster natural means of communication within a buddy team. If they haven't invested in expensive full-face masks that incorporate through-water voice transmission, buddy divers must communicate via non-audible means: standardized hand signals or submersible writing slates. [33]
In an effort to insure universal, easily understood signals between divers, [34] the Recreational Scuba Training Council agencies together defined a set of hand signals intended for universal use, which are taught to diving students early in their entry-level diving courses. [33] Hand signals may also have more than one variation that may benefit when one hand is occupied, or in limited visibility. In darkness it may be necessary to illuminate the hand signal for it to be understandable.
Underwater slates are useful when there is more detailed information to communicate or remember. A large variety of designs are available. Some clip to the divers BCD, some fit into pockets, some integrated with other units such as the compass and some attach to the wrist or forearm with bungee straps. The basic parts comprise just an underwater pencil attached to a plastic board by a short tether, and a way to attach these to a convenient point on the diver's equipment. Slates are particularly useful for information that must be written down prior to a dive and referenced during the dive: elements of the dive plan (depths, durations, decompression schedule) or a drawn map of the dive area. [35]
A buddy line is a line or strap physically tethering two scuba divers together underwater to avoid separation in low visibility conditions. [36] A buddy line is commonly a short length of about two meters with a floating element between divers to reduce risk of snagging on the bottom. A buddy line is a means of communication. It doesn't need to be particularly strong or secure, but should not pull off under moderate loads. Divers may communicate by rope signals, but more usually just use the line to attract attention before moving closer and communicating by hand signals. The disadvantage of a buddy line is an increased risk of snagging and entanglement. Divers may need to disconnect the line quickly at either end in an emergency, which is done via a quick release mechanism or by cutting the line, both of which require at least one free hand. A velcro strap requires no tools for release and can be released under tension.[ citation needed ]
In more advanced diving (particularly penetration diving) divers often use additional underwater communication methods, including signalling with lights, pulls along connecting lines, or tapping on tanks. [35]
Ultrasonic signalling devices that attract the buddy's attention by vibration have been marketed and may have some limited utility. [37]
The generally accepted procedure in the case of buddy separation (or lost buddy), in a recreational open water dive is to search for the buddy for one minute, and if not found in this time, to start the ascent, following appropriate procedures based on any decompression obligations. This rule is taught fairly consistently by recreational diver training agencies, but it is not compulsory and variations in this procedure may be agreed upon by the divers during dive planning. Compliance is variable, as ascent in most cases implies termination of the dive, which may not be welcome to either party. Loss of buddy contact is commonly reported in diving fatalities, but in many cases it is not clear whether loss of contact was a cause or an effect of the fatal incident. [38] [5]
With buddy diving, each of the divers is presumed to have a responsibility to the other. [39] The actual legal responsibilities for recreational buddies may vary between jurisdictions and are seldom if ever clear. The buddies are expected to monitor each other, to stay close enough together to help in an emergency, to behave safely and to follow the plan agreed by the group before the dive. [1] When the system fails, it is generally because one of the divers does not fulfill his or her responsibilities as a buddy. [40] If one of the divers is incapable of providing the expected assistance the buddy system has already failed. With professional divers, buddy responsibility may vary and will be specified in the code of practice, operations manual, and dive plan. Each diver in this case must be capable of fulfilling their responsibilities according to the dive plan. [5]
The responsibilities of each buddy during a recreational dive are generally accepted to be: [41] [42] [4]
These responsibilities may not be legally binding. A recreational diver is not normally expected to take unacceptable risks to their own safety to assist another recreational diver, [7] and it is not reasonable to expect performance of skills in which the diver has not been trained or assessed.
The US Navy does not require buddy diving in all circumstances, but it does specify that buddy divers are responsible for both the assigned task and each other's safety. They must: [44]
Other professional divers' buddy responsibilities are likely to be similar and should be clearly described in the operations manual.
With the increased popularity of solo diving as a possible alternative to the buddy system, there has been debate as to what really constitutes safe diving practise and how divers can best control the risks associated with their sport. [2] Statistically speaking, scuba is a reasonably safe activity, [45] with incidents of injury below several other "risk" sports such as football, horse riding or even tennis.[ citation needed ] Yet unlike these other sports, scuba divers are in a hostile environment for which humans are not adapted, breathing from a portable and limited capacity life support system. Under these conditions, fatality is always a possible outcome, as even simple equipment or procedural problems can be mishandled. In dealing with this reality a number of major concerns about potentially inherent flaws or negative impacts that can exist within the buddy system have been identified. [2] Few, if any, of these problems, are defects in the concept of the buddy system, they are problems with the application of the system. [2]
Every time I read, in an accident [ sic ] report, that the buddy system failed, I get livid. The buddy system does not fail, it is the people using it that have the problems. The system is fine, it is the implementation that falls down. [46]
— Glen Egstrom, Emergency air sharing
There are circumstances in which the buddy system must be abandoned as unacceptably risky to the buddy. The buddy is not expected or legally obliged to unduly put themself at risk of death or serious injury in the attempt to rescue a diver in distress. The level of risk acceptable has been determined in some legislations to be that acceptable to the reasonable man . A conviction of criminal negligence made by a magistrate on Malta was overthrown by the appeals judge on these grounds, among others. [43]
Liability issues strongly affect the structure of the diving industry, its organisation and even the implementation of recommended diving practices – and this is very much the case with buddy diving. Diving is a risky sport, where serious accidents occasionally occur. In an increasingly litigious world, accidents often trigger a search for "blame", and aspersions of blame often trigger ensuing litigation. It is a natural thing for those who may face the potential risks of litigation to take measures to mitigate these risks. Diving certification agencies must necessarily insure themselves against liability risks and must act to minimise the cost of this insurance for both themselves and their operatives. The buddy system, beneficial as it can be in enhancing diver safety, has the legal effect of creating an involved intermediary person between the certifying agency and any injured party, an intermediary who could be easily identified as not having provided "duty of care" if an accident occurs. [7] This may afford a legal cushion for the agency, or trainer, or boat - but it is not exactly good news for someone acting in the role of a buddy. The more skilled the buddy partner, the more these duties of care may be assumed to increase, often without legal justification.
Liability waivers are signed whenever a diver interacts with an operative of the diving industry, e.g. the training agent or dive boat. [56] No such waiver is commonplace for the buddy in a buddy team. As case law develops, more precedents become established for situations where buddy action may make them particularly liable. [7] It is recommended[ by whom? ] now that buddy divers carry insurance that provides coverage of themselves against legal actions by buddies, particularly if diving takes place in those countries where a culture of litigation may exist. This is particularly necessary for scuba diving professionals who earn a living in the recreational diving industry, when they "buddy-up". More experienced or more qualified divers may also unreasonably be expected to bear a higher duty of care for their less qualified buddies,[ citation needed ] and therefore a serious burden can be placed on a vacationing diver asked to buddy up with a stranger, especially in litigious jurisdictions, and specially if either diver is not as competent as their certification and experience may suggest.
A divemaster (DM) is a role that includes organising and leading recreational dives, particularly in a professional capacity, and is a qualification used in many parts of the world in recreational scuba diving for a diver who has supervisory responsibility for a group of divers and as a dive guide. As well as being a generic term, 'Divemaster' is the title of the first professional rating of many training agencies, such as PADI, SSI, SDI, NASE, except NAUI, which rates a NAUI Divemaster under a NAUI Instructor but above a NAUI Assistant Instructor. The divemaster certification is generally equivalent to the requirements of ISO 24801-3 Dive Leader.
Recreational diver training is the process of developing knowledge and understanding of the basic principles, and the skills and procedures for the use of scuba equipment so that the diver is able to dive for recreational purposes with acceptable risk using the type of equipment and in similar conditions to those experienced during training.
Recreational diving or sport diving is diving for the purpose of leisure and enjoyment, usually when using scuba equipment. The term "recreational diving" may also be used in contradistinction to "technical diving", a more demanding aspect of recreational diving which requires more training and experience to develop the competence to reliably manage more complex equipment in the more hazardous conditions associated with the disciplines. Breath-hold diving for recreation also fits into the broader scope of the term, but this article covers the commonly used meaning of scuba diving for recreational purposes, where the diver is not constrained from making a direct near-vertical ascent to the surface at any point during the dive, and risk is considered low.
The buddy check is a procedure carried out by scuba divers using the buddy system where each diver checks that the other's diving equipment is configured and functioning correctly just before the start of the dive. A study of pre-dive equipment checks done by individual divers showed that divers often fail to recognize common equipment faults. By checking each other's equipment as well as their own, it is thought to be more likely that these faults will be identified prior to the start of the dive.
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.
Solo diving is the practice of self-sufficient underwater diving without a "dive buddy", particularly with reference to scuba diving, but the term is also applied to freediving. Professionally, solo diving has always been an option which depends on operational requirements and risk assessment. Surface supplied diving and atmospheric suit diving are commonly single diver underwater activities but are accompanied by an on-surface support team dedicated to the safety of the diver, including a stand-by diver, and are not considered solo diving in this sense.
Buddy breathing is a rescue technique used in scuba diving "out-of-gas" emergencies, when two divers share one demand valve, alternately breathing from it. Techniques have been developed for buddy breathing from both twin-hose and single hose regulators, but to a large extent it has been superseded by safer and more reliable techniques using additional equipment, such as the use of a bailout cylinder or breathing through a secondary demand valve on the rescuer's regulator.
A pony bottle or pony cylinder is a small diving cylinder which is fitted with an independent regulator, and is usually carried by a scuba diver as an auxiliary scuba set. In an emergency, such as depletion of the diver's main air supply, it can be used as an alternative air source or bailout bottle to allow a normal ascent in place of a controlled emergency swimming ascent. The key attribute of a pony bottle is that it is a totally independent source of breathing gas for the diver.
In underwater diving, an alternative air source, or more generally alternative breathing gas source, is a secondary supply of air or other breathing gas for use by the diver in an emergency. Examples include an auxiliary demand valve, a pony bottle and bailout bottle.
An emergency ascent is an ascent to the surface by a diver in an emergency. More specifically, it refers to any of several procedures for reaching the surface in the event of an out-of-gas emergency, generally while scuba diving.
Diver training is the set of processes through which a person learns the necessary and desirable skills to safely dive underwater within the scope of the diver training standard relevant to the specific training programme. Most diver training follows procedures and schedules laid down in the associated training standard, in a formal training programme, and includes relevant foundational knowledge of the underlying theory, including some basic physics, physiology and environmental information, practical skills training in the selection and safe use of the associated equipment in the specified underwater environment, and assessment of the required skills and knowledge deemed necessary by the certification agency to allow the newly certified diver to dive within the specified range of conditions at an acceptable level of risk. Recognition of prior learning is allowed in some training standards.
A diving instructor is a person who trains, and usually also assesses competence, of underwater divers. This includes freedivers, recreational divers including the subcategory technical divers, and professional divers which includes military, commercial, public safety and scientific divers.
Scuba gas management is the aspect of scuba diving which includes the gas planning, blending, filling, analysing, marking, storage, and transportation of gas cylinders for a dive, the monitoring and switching of breathing gases during a dive, efficient and correct use of the gas, and the provision of emergency gas to another member of the dive team. The primary aim is to ensure that everyone has enough to breathe of a gas suitable for the current depth at all times, and is aware of the gas mixture in use and its effect on decompression obligations, nitrogen narcosis, and oxygen toxicity risk. Some of these functions may be delegated to others, such as the filling of cylinders, or transportation to the dive site, but others are the direct responsibility of the diver using the gas.
Scuba skills are skills required to dive safely using self-contained underwater breathing apparatus, known as a scuba set. Most of these skills are relevant to both open-circuit scuba and rebreather scuba, and many also apply to surface-supplied diving. Some scuba skills, which are critical to divers' safety, may require more practice than standard recreational training provides to achieve reliable competence.
Dive leader is the title of an internationally recognised recreational diving certification. The training standard describes the minimum requirements for dive leader training and certification for recreational scuba divers in international standard ISO 24801-3 and the equivalent European Standard EN 14153-3. Various organizations offer training that meets the requirements of the dive leader standard. Some agencies use the title "Dive Leader" for their equivalent certification, but several other titles are also used, "Divemaster" may be the most widespread, but "Dive Supervisor" is also used, and should not be confused with the very different status and responsibilities of a professional diving supervisor. CMAS affiliates certifications which meet the requirements of CMAS 3-star diver should meet the standard by default. The occupation of a dive leader is also known as "dive guide", and is a specialist application of a "tour guide".
Diving safety is the aspect of underwater diving operations and activities concerned with the safety of the participants. The safety of underwater diving depends on four factors: the environment, the equipment, behaviour of the individual diver and performance of the dive team. The underwater environment can impose severe physical and psychological stress on a diver, and is mostly beyond the diver's control. Equipment is used to operate underwater for anything beyond very short periods, and the reliable function of some of the equipment is critical to even short-term survival. Other equipment allows the diver to operate in relative comfort and efficiency, or to remain healthy over the longer term. The performance of the individual diver depends on learned skills, many of which are not intuitive, and the performance of the team depends on competence, communication, attention and common goals.
The history of scuba diving is closely linked with the history of the equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
The following index is provided as an overview of and topical guide to underwater diving: Links to articles and redirects to sections of articles which provide information on each topic are listed with a short description of the topic. When there is more than one article with information on a topic, the most relevant is usually listed, and it may be cross-linked to further information from the linked page or section.
A dive briefing or pre-dive briefing is a meeting of the diving team or dive group before the dive to allow the supervisor, dive leader or dive boat skipper to inform the attendees of the dive plan, contingency plans and emergency plans for the dive. The amount of detail presented should be appropriate to the dive, but there are several topics which are considered standard components of a dive briefing. The topics may vary depending on context.
Recreational scuba certification levels are the levels of skill represented by recreational scuba certification. Each certification level is associated with a specific training standard published by the certification agency, and a training programme associated with the standard., though in some cases recognition of prior learning can apply. These levels of skill can be categorised in several ways:
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