Diver training

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.

Recreational diver training has historically followed two philosophies, based on the business structure of the training agencies. The not-for profit agencies tend to focus on developing the diver's competence in relatively fewer stages, and provide more content over a longer programme, than the for-profit agencies, which maximise profit and customer convenience by providing a larger number of shorter courses with less content and fewer skills per course. The more advanced skills and knowledge, including courses focusing on key diving skills like good buoyancy control and trim, and environmental awareness, are available by both routes, but a large number of divers never progress beyond the entry level certification, and only dive on vacation, a system by which skills are more likely to deteriorate than improve due to long periods of inactivity. This may be mitigated by refresher courses, which tend to target skills particularly important in the specific region, and may focus on low impact diving skills, to protect the environment that the service provider relies on for their economic survival.

Diver training is closely associated with diver certification or registration, the process of application for, and issue of, formal recognition of competence by a certification agency or registration authority. The training generally follows a programme authorised by the agency, and competence assessment follows the relevant diver training standard.

Training in work skills specific to the underwater environment may be included in diver training programmes, but is also often provided independently, either as job training for a specific operation, or as generic training by specialists in the fields. Professional divers will also learn about legislative restrictions and occupational health and safety relating to diving work.

Prerequisites

The entry requirements for diver training depend on the specific training involved, but generally include medical fitness to dive.

Fitness to dive, (also medical fitness to dive), is the medical and physical suitability of a diver to function safely in the underwater environment using underwater diving equipment and procedures. Depending on the circumstances it may be established by a signed statement by the diver that he or she does not suffer from any of the listed disqualifying conditions and is able to manage the ordinary physical requirements of diving, to a detailed medical examination by a physician registered as a medical examiner of divers following a procedural checklist, and a legal document of fitness to dive issued by the medical examiner.

The most important medical is the one before starting diving, as the diver can be screened to prevent exposure when a dangerous condition exists. Other important medicals are after some significant illness where medical intervention is needed. This has to be done by a doctor who is competent in diving medicine, and can not be done by prescriptive rules.

Psychological factors can affect fitness to dive, particularly where they affect response to emergencies, or risk taking behaviour. The use of medical and recreational drugs, can also influence fitness to dive, both for physiological and behavioural reasons. In some cases prescription drug use may have a net positive effect, when effectively treating an underlying condition, but frequently the side effects of effective medication may have undesirable influences on the fitness of diver, and most cases of recreational drug use result in an impaired fitness to dive, and a significantly increased risk of sub-optimal response to emergencies.

Formal educational prerequisites are variable. Diving skills are largely physical, but for professional diving a measure of literacy and numeracy is necessary to allow a reasonable chance of success with the theoretical knowledge requirements, and for effective on-site communication within the dive team. The international ''lingua franca'' of offshore diving operations is English.

Some training standards include an ability to swim as a prerequisite.

Format

Diver training is a form of competency-based adult education that generally occurs at least partly in a formal training environment for the components specified by diver training standards and for which certification is issued. There are also non-formal and informal aspects where certified divers extend their competence and experience by practicing the basic skills and learning other complementary skills in the field.

Prior learning may be recognised where applicable and permitted by the training standard. This is typically done by assessment against the requirements of the standards using the same methods as in formal training programmes for safety-critical skills and knowledge, and by accepting verifiable evidence of experience, as in signed and witnessed logbook entries.

Diving theory

Diving theory is the basic knowledge of the physical and physiological effects of the underwater environment on the diver.

Diving physics are the aspects of physics which directly affect the underwater diver and which explain the effects that divers and their equipment are subject to underwater which differ from the normal human experience out of water. These effects are mostly consequences of immersion in water, the hydrostatic pressure of depth and the effects of the pressure on breathing gases. An understanding of the physics is useful when considering the physiological effects of diving and the hazards and risks of diving.

Diving physiology is the physiological influences of the underwater environment on the physiology of air-breathing animals, and the adaptations to operating underwater, both during breath-hold dives and while breathing at ambient pressure from a suitable breathing gas supply. It, therefore, includes both the physiology of breath-hold diving in humans and other air-breathing animals, and the range of physiological effects generally limited to human ambient pressure divers either freediving or using underwater breathing apparatus. Several factors influence the diver, including immersion, exposure to the water, the limitations of breath-hold endurance, variations in ambient pressure, the effects of breathing gases at raised ambient pressure, effects caused by the use of breathing apparatus, and sensory impairment. All of these may affect diver performance and safety.

Immersion affects fluid balance, circulation and work of breathing. Exposure to cold water can result in the harmful cold shock response, the helpful diving reflex and excessive loss of body heat. Breath-hold duration is limited by oxygen reserves, and the risk of hypoxic blackout, which has a high associated risk of drowning.

Large or sudden changes in ambient pressure have the potential for injury known as barotrauma. Breathing under pressure involves several effects. Metabolically inactive gases are absorbed by the tissues and may have narcotic or other undesirable effects, and must be released slowly to avoid the formation of bubbles during decompression. Metabolically active gases have a greater effect in proportion to their concentration, which is proportional to their partial pressure, which for contaminants is increased in proportion to absolute ambient pressure.

Work of breathing is increased by increased density and viscosity of the breathing gas, artifacts of the breathing apparatus, and hydrostatic pressure variations due to posture in the water. The underwater environment also affects sensory input, which can impact on safety and the ability to function effectively at depth.

Decompression theory is the study and modelling of the transfer of the inert gas component of breathing gases from the gas in the lungs to the tissues and back during exposure to variations in ambient pressure. In the case of underwater diving, this mostly involves ambient pressures greater than the local surface pressure, but astronauts, high altitude mountaineers, and travellers in aircraft which are not pressurised to sea level pressure, are generally exposed to ambient pressures less than standard sea level atmospheric pressure. In all cases, the symptoms caused by decompression occur during or within a relatively short period of minutes to hours, or occasionally days, after a significant pressure reduction. The term "decompression" derives from the reduction in ambient pressure experienced by the organism and refers to both the reduction in pressure and the process of allowing dissolved inert gases to be eliminated from the tissues during and after this reduction in pressure. The uptake of gas by the tissues is in the dissolved state, and elimination also requires the gas to be dissolved, however a sufficient reduction in ambient pressure may cause bubble formation in the tissues, which can lead to tissue damage and the symptoms known as decompression sickness, and also delays the elimination of the gas.

Decompression modeling attempts to explain and predict the mechanism of gas elimination and bubble formation within the organism during and after changes in ambient pressure, and provides mathematical models which attempt to predict acceptably low risk and reasonably practicable procedures for decompression in the field. Both deterministic and probabilistic models have been used, and are still in use.

Diving medicine, also called undersea and hyperbaric medicine (UHB), is the diagnosis, treatment and prevention of conditions caused by humans entering the underwater environment. It includes the effects on the body of pressure on gases, the diagnosis and treatment of conditions caused by marine hazards and how a diver's fitness to dive affects the diver's safety.

Hyperbaric medicine is a related field associated with diving, since recompression in a hyperbaric chamber is used as a treatment for two of the most significant diving-related illnesses, decompression sickness and arterial gas embolism.

Diving medicine deals with medical research on issues of diving, the prevention of diving disorders, treatment of diving accidents and diving fitness. The field includes the effect of breathing gases and their contaminants under high pressure on the human body and the relationship between the state of physical and psychological health of the diver and safety.

In diving accidents it is common for multiple disorders to occur together and interact with each other, both causatively and as complications.

Diving medicine is a branch of occupational medicine and sports medicine, and first aid for diving injuries an important part of diver education.

Teaching of diving theory is usually provided as classroom lecture sessions with formative assessment tasks and exercises and a written examination for final assessment. Blended learning is used by some agencies and schools to ensure a more consistent standard.

A working knowledge of the Diving environment in which the diver is likely to operate is necessary so that the diver can to some extent understand and predict the likely conditions they will experience while diving, and the associated hazards and risks. This knowledge is also necessary for informed consent in terms of health and safety legislation, and for diving supervisors, instructors, dive leaders and recreational divers it is essential for the assessment of the risk to which they or the people for whom they have a duty of care will be exposed while diving.

Dive planning

Dive planning is the practical application of theoretical knowledge and understanding. It is the process of planning an underwater diving operation. The purpose of dive planning is to increase the probability that a dive will be completed safely and the goals achieved. Some form of planning is done for most underwater dives, but the complexity and detail considered may vary enormously. In most professional diving, dive planning is mainly the responsibility of the supervisor, but the diver is expected to understand the process sufficiently to know when it has been done correctly. In recreational diving, unless under training, the diver is generally considered equally responsible for the planning of any dive they participate in, along with the other involved divers, so dive planning at the level of certification is an important aspect of recreational diver training.

Professional diving operations are usually formally planned and the plan documented as a legal record that due diligence has been done for health and safety purposes. Recreational dive planning may be less formal, but for complex technical dives, can be as formal, detailed and extensive as most professional dive plans. A professional diving contractor will be constrained by the code of practice, standing orders or regulatory legislation covering a project or specific operations within a project, and is responsible for ensuring that the scope of work to be done is within the scope of the rules relevant to that work. A recreational (including technical) diver or dive group is generally less constrained, but nevertheless is almost always restricted by some legislation, and often also the rules of the organisations to which the divers are affiliated.

The planning of a diving operation may be simple or complex. In some cases the processes may have to be repeated several times before a satisfactory plan is achieved, and even then the plan may have to be modified on site to suit changed circumstances. The final product of the planning process may be formally documented or, in the case of recreational divers, an agreement on how the dive will be conducted. A diving project may consist of a number of related diving operations.

A documented dive plan may contain elements from the following list:
*Overview of Diving Activities
*Schedule of Diving Operations
*Specific Dive Plan Information
*Budget

For scuba dives, selection of the breathing gases and calculation of the required quantities is one of the most complex parts of dive planning, and is done in parallel with planning of the dive profile and decompression plan.

The general aspects of dive planning include the following, but not all of these apply to every dive, and in many cases there is no choice available to the diver, who must work within the constraints of what is available and appropriate to their level of competence. Planning of a complex dive may be an iterative process, and the order of steps may vary.
*Purpose of the dive.
*Site analysis, environmental aspects and known hazards of the site and task.
*Selection of mode and techniques of diving. This aspect is often severely limited, and for training purposes is usually linked to the training standard.
*Selection of team.
*Estimation of depth and time, dive profile, decompression plan. These are generally constrained by the purpose and site.
*Choice of equipment.
*Gas planning for the planned profile, allowing for contingencies and foreseeable emergencies.
*Risk assessment is based on the planning to this point. The assessed risk must be acceptable if the dive is to be done. It may be possible to reduce an unacceptable risk by changing the plan.
*Contingency and emergency planning depend on the outcome of the risk assessment.
*Other logistical considerations, arranging permits and permission to dive, schedule of tasks and budgeting.
*Schedule of tasks and budget.
Teaching of dive planning typically omits any aspects not relevant to the certification level, and to some extent the certification will be defined by the competence requirements for dive planning. Assessment of dive planning competence is commonly a combination of written exams on the details, and direct observation of performance of dive planning tasks.

Other theory based knowledge

Professional divers are required to be familiar with the law regulating their occupation, and any national or international codes of practice that apply in the region where they will practice. National legislation will commonly be included in the curriculum for entry level professional diving, and may be recognised as prior learning for further diver training. The level of knowledge required of a diving supervisor is considerably higher, and is usually part of supervisor training and assessment.

Occupational heath and safety are important aspects of professional diving. The diver is expected to understand the hazards, risks and potential consequences of diving at work and using the equipment provided in the environment of the project, and though risk assessment and team safety on the job are primarily the responsibility of the supervisor and the employer, the diver is also responsible as a member of the team and is expected to have sufficient knowledge of the processes and risks to reasonably accept the risk assessment.

Diving skills

Diving skills can be grouped by skills relating to the mode of diving – freediving, scuba, surface supplied or saturation diving – and whether the skill is a standard skill used in everyday diving, an emergency skill to keep oneself alive when something goes wrong, or a rescue skill to be used in the attempt to assist another diver in difficulty.

Scuba skills are the skills required to dive safely using self-contained underwater breathing apparatus, (scuba). Most of these skills are relevant to both open circuit and rebreather scuba, and many are also relevant to surface-supplied diving. Those skills which are critical to the safety of the diver may require more practice than is usually provided during training to achieve reliable long-term proficiency

Some of the skills are generally accepted by recreational diver certification agencies as necessary for any scuba diver to be considered competent to dive without direct supervision, and others are more advanced, though some diver certification and accreditation organizations may consider some of these to also be essential for minimum acceptable entry level competence. Divers are instructed and assessed on these skills during basic and advanced training, and are expected to remain competent at their level of certification, either by practice or refresher courses.

The skills include selection, functional testing, preparation and transport of scuba equipment, dive planning, preparation for a dive, kitting up for the dive, water entry, descent, breathing underwater, monitoring the dive profile (depth, time and decompression status), personal breathing gas management, situational awareness, communicating with the dive team, buoyancy and trim control, mobility in the water, ascent, emergency and rescue procedures, exit from the water, unkitting after the dive, cleaning and preparation of equipment for storage and recording the dive, within the scope of the diver's certification. Some of these skills affect the diver's ability to minimise adverse environmental impact.

Surface supplied diving skills are the skills and procedures required for the safe operation and use of surface-supplied diving equipment. Besides these skills, which may be categorised as standard operating procedures, emergency procedures and rescue procedures, there are the actual working skills required to do the job, and the procedures for safe operation of the work equipment other than diving equipment that may be needed.

Some of the skills are common to all types of surface-supplied equipment and deployment modes, others are specific to the type of bell or stage, or to saturation diving. There are other skills required of divers which apply to the surface support function, and some of those are also mentioned here.

Standard diving skills include skills like buoyancy control, finning, mask clearing, pre-dive checks and diver communications. They are used all the time, and are seldom lost due to lack of practice. Usually the diver gets better at these skills over time due to frequent repetition.

Emergency skills should seldom be needed, and may not be practiced often after training, but when an emergency occurs, the ability to perform the skill adequately, if not necessarily flawlessly, may be critical to the diver's health or survival.

Rescue skills are more relevant to keeping a co-worker alive than oneself. If lucky, a diver may never need to attempt the rescue of another, and these skills also need periodical scheduled repetition to retain competence. First aid skills are a similar category, and are generally re-assessed periodically to remain in date. It is generally considered a responsibility of the employer to ensure that their employees get sufficient practice in emergency and rescue skills.

Training methods for diving skills

Diving skills are practical skills, suitable for learning by performing and improvement by correct repetition and overlearning. Many of the diving skills are safety-critical – incorrect performance can put the diver or another person at risk, and in some cases incorrect response can be rapidly fatal. The skill is generally discussed, demonstrated by a skilled practitioner, and then attempted by the learner in controlled conditions. Repetition with feedback from the instructor is generally continued until the skill can be performed reliably under normal conditions. Once mastered, the critical skills may be combined with related activities and practiced until they become second nature. Professional, particularly military training, may overtrain skills until they are internalised to the extent of being conditioned reflexes, requiring very little conscious thought, as adequate performance under highly stressed and task loaded conditions may be necessary for survival.

Situations can develop during dives where external stress can distract the diver and hinder prompt and appropriate response. This can put the diver at immediate risk. Stress exposure training, which includes exercise of important existing skills in a stressful and distracting environment to develop the ability to perform them reliably in spite of the circumstances, can be used to prepare divers to function effectively under high-stress conditions. This is done after the diver has mastered the skills in a benign environment under conditions conducive to learning and retention of the skills. This form of training is generally not used in recreational diver training, and is more likely to be encountered in military and other professional diving, and occasionally in technical diver training. It is not usually required by the training standards.

Training venues for diving skills

Initial skills training is restricted to confined water, a diving environment that is enclosed and bounded sufficiently for safe training purposes. This generally implies that conditions are not affected by geographic or weather conditions, and that divers can not get lost. Swimming pools and diver training tanks are included in this category. A diver training tank is a container of water large and deep enough to practice diving and underwater work skills, usually with a window through which the exercises can be viewed by the instructor. Once competence has been demonstrated in confined water, repetition of skills in open water is usual. This is generally done in combinations that simulate realistic circumstances when reasonably practicable.

First aid skills

Most professional divers are required by national or state legislation to be qualified first aid providers to a specified standard. First aid training is not generally considered to be an integral part of diver training, but may be provided in parallel. First aid registration is generally valid for a limited period and must be updated to stay in-date to dive. Most third party first aid training does not include specific first aid for diving injuries such as high concentration oxygen administration. This is generally additional to the standard first aid training.

In recreational diving a first aid certification is needed for Rescue Diver

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