Dive planning
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Dive planning 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.
Professional diving Professional diving is underwater diving where the divers are paid for their work. The procedures are often regulated by legislation and codes of practice as it is an inherently hazardous occupation and the diver works as a member of a team. Du ...
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 Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure ...
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


Objective

Commercial diving contractors will develop specifications for the operation in cooperation with the client, who will normally provide a specific objective. The client will generally specify what work is to be done, and the diving contractor will deal with the logistics of how to do it. Other professional divers will usually plan their diving operations around an objective related to their primary occupation. Recreational divers will generally choose an objective for entertainment value, or for training purposes. It will generally be necessary to specify the following: * Work to be done, or the recreational equivalent * Equipment needed * Procedures to be used * Personnel required * Places * Times


Analysis of available information on the site

* Expected surface conditions, such as sea state, air temperature, and
wind chill factor Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...
* Expected underwater conditions, including water temperature, depth, type of bottom, tides and currents, visibility, extent of pollution, and other hazards * Assistance and emergency information, including location, status, and contact procedures for the nearest
recompression chamber A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of ...
, evacuation and rescue facilities, and nearest hospital. * Location and accessibility of the site


Selection of techniques and mode of diving

Detailed planning depends on the mode and techniques selected for the dive, and the choice of these depends to a large extent on the physical constraints of the dive, but also to the legal, financial and procedural constraints of the divers. The mode and techniques chosen must also allow the dive to be done at an acceptable level of risk. There is usually more than one mode which is physically feasible, and often a choice between modes which are otherwise acceptable. In some cases detailed planning may show that the initial choice was not appropriate, and the process has to be repeated for an alternative choice.


Diving without breathing apparatus

Free diving Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear. Besides the limits of breath- ...
does not involve the use of external breathing devices, but relies on a diver's ability to hold his or her breath until resurfacing. Free diving is limited in depth and time, but for some purposes it may be suitable.


Scuba diving

Diving Diving most often refers to: * Diving (sport), the sport of jumping into deep water * Underwater diving, human activity underwater for recreational or occupational purposes Diving or Dive may also refer to: Sports * Dive (American football), a ...
with a
self-contained underwater breathing apparatus A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diver and provides the diver with breathing gas at the ambient pressure. ''Scuba'' is an anacronym for self-contained underwater breathing ...
, which is completely independent of surface supply, provides the diver with the advantages of mobility and horizontal range far beyond what is possible when supplied from the surface by the umbilical hoses of
surface-supplied diving equipment Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scub ...
. Scuba has limitations of
breathing gas A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed h ...
supply, communications between diver and surface are problematic, the location of the diver may be difficult to monitor, and it is considered a higher-risk mode of diving in most circumstances. Scuba is specifically forbidden for some professional applications. Decompression is often avoided, and if necessary, is generally in-water, but may use a variety of gases.


Open circuit

Open-circuit scuba systems discharge the breathing gas into the environment as it is exhaled, and consist of one or more
diving cylinder A diving cylinder or diving gas cylinder is a gas cylinder used to store and transport high pressure gas used in diving operations. This may be breathing gas used with a scuba set, in which case the cylinder may also be referred to as a scu ...
s containing breathing gas at high pressure connected to a primary
diving regulator A diving regulator is a pressure regulator that controls the pressure of breathing gas for diving. The most commonly recognised application is to reduce pressurized breathing gas to ambient pressure and deliver it to the diver, but there are als ...
, and may include additional cylinders for decompression gas or emergency breathing gas.


Rebreathers

Closed-circuit or semi-closed circuit rebreather systems allow recycling of exhaled gases. This reduces the volume of gas used, so that a smaller cylinder, or cylinders, than open-circuit scuba may be used for the equivalent dive duration, and giving the ability to spend far more time underwater compared to open circuit for the same gas consumption. Rebreathers also produce far less bubble volume and less noise than scuba, which makes them attractive to military, scientific and media divers. They also have a larger number of critical
failure mode Failure causes are defects in design, process, quality, or part application, which are the underlying cause of a failure or which initiate a process which leads to failure. Where failure depends on the user of the product or process, then human er ...
s, are more expensive and require more training to use at a reasonable level of safety.


Surface supplied diving

Breathing gases may be supplied from the surface through a
diver's umbilical Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scub ...
, or airline hose, which provides breathing gas, communications and a safety line, with options for a hot water hose for heating, a video cable and gas reclaim line. The diver's breathing gas supply is significantly more secure than for scuba; communications are simplified and the divers position is either known or can be traced reliably by following the umbilical. Several major risks are thereby mitigated, but the system also has serious disadvantages in some applications, as diver mobility is constrained by the length of the umbilical, and it may snag on obstructions. Surface-oriented, or bounce diving, is how commercial divers refer to diving operations where the diver starts and finishes the diving operation at atmospheric pressure. The alternative, while retaining surface supply, is
saturation diving Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working ...
. For bounce dives, the diver may be deployed directly, often from a
diving support vessel A diving support vessel is a ship that is used as a floating base for professional diving projects. Basic requirements are the ability to keep station accurately and reliably throughout a diving operation, often in close proximity to drilling or ...
or indirectly via a
diving bell A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which c ...
. Decompression procedures include in-water decompression or surface decompression in a deck chamber. Small closed bell systems which include a two-man bell, a launch and recovery frame and a chamber for decompression after
transfer under pressure 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 r ...
(TUP) are reasonably mobile, and suited to deep bounce dives.


Saturation diving

Saturation diving Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working ...
lets divers live and work at depth for days or weeks at a time. After working in the water, divers are transferred in a closed
diving bell A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which c ...
to rest and live in a dry pressurized
underwater habitat Underwater habitats are underwater structures in which people can live for extended periods and carry out most of the basic human functions of a 24-hour day, such as working, resting, eating, attending to personal hygiene, and sleeping. In thi ...
on the bottom or a saturation life support system of pressure chambers at the surface. Decompression at the end of the dive may take many days, but since it is done only once for a long period of exposure, rather than after each of many shorter exposures, the overall risk of decompression injury to the diver and the total time spent decompressing are reduced. This type of diving allows greater economy of work and enhanced safety, but the capital and running costs are high and the systems are expensive to transport. Mobility of the diver is restricted because of the umbilical.


Atmospheric diving suits

Atmospheric diving suits An atmospheric diving suit (ADS) is a small one-person articulated submersible which resembles a suit of armour, with elaborate pressure joints to allow articulation while maintaining an internal pressure of one atmosphere. An ADS can enable di ...
can be used for very deep dives of up to for many hours, and eliminate several
physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
dangers associated with
deep diving Deep diving is underwater diving to a depth beyond the norm accepted by the associated community. In some cases this is a prescribed limit established by an authority, while in others it is associated with a level of certification or training, an ...
: the occupant need not decompress; there is no need for special gas mixtures; and there is no danger of
decompression sickness Decompression sickness (abbreviated DCS; also called divers' disease, the bends, aerobullosis, and caisson disease) is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompressio ...
or
nitrogen narcosis Narcosis while diving (also known as nitrogen narcosis, inert gas narcosis, raptures of the deep, Martini effect) is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gas ...
. Disadvantages include high cost, limited availability, bulk and limited diver dexterity.


Diving team selection

The diving team personnel selection will depend largely on the diving mode selected and organisational requirements. Professional dive team members will generally be selected on documented evidence of proven competence or qualification for the tasks allocated. Professional diving teams will usually include (the precise terminology may vary between organisations): * A supervisor * One or more working divers * One or more stand-by divers * One or more diver's attendants * Other surface support personnel, which may include: ** Medical support (not necessarily on-site) ** Chamber operator or
life support technician Professional diving is underwater diving where the divers are paid for their work. The procedures are often regulated by legislation and codes of practice as it is an inherently hazardous occupation and the diver works as a member of a team. Du ...
** Support vessel crew ** Equipment technicians,
gas panel Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from sc ...
operators, timekeepers, riggers Technical teams will also generally base appointments on proven competence, certification or personal trust. Technical diving groups vary in complexity, but will generally comprise: * Dive team * In-water support team * Surface support team Recreational groupings may be based on personal experience and trust, but are frequently relatively arbitrary allocations by the service provider, based on
certification Certification is the provision by an independent body of written assurance (a certificate) that the product, service or system in question meets specific requirements. It is the formal attestation or confirmation of certain characteristics of a ...
. Recreational diving groups commonly comprise a buddy pair of divers, but may also be a solo diver or a group of divers who will be led by a
divemaster 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 respo ...
. Selection may be by mutual agreement to dive together, or may simply be the result of booking on the same dive.


Depth and time

Depth is often one of the more straightforward parameters, as it is often fixed by the
topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...
of the site. Time is influenced by limitations of equipment and decompression constraints, as well as the actual time required to perform the intended task, which in turn is influenced by the underwater environment in general, and specific to the site.


Environmental factors

The specific diving environment must be taken into account during dive planning. The environment at the dive site will determine several factors which may require specific planning, such as the depth, water salinity and altitude which affect decompression planning, an overhead environment affects navigation and gas planning, water temperature and contaminants affect the choice of exposure and environmental protection, site topography affects choice of entry and exit points.


Hazards of the proposed diving operation

Divers face specific physical and health risks when they go underwater with diving equipment, or use high pressure breathing gas. A hazard is any biological, chemical, physical, mechanical or environmental agent or situation that poses a level of threat to life, health, property, or environment. The presence of a combination of several hazards simultaneously is common in diving, and the effect is generally increased risk to the diver, particularly where the occurrence of an incident due to one hazard triggers other hazards with a resulting cascade of incidents. Diving hazards may be classified under several groups: * The aquatic environment itself * Use of breathing equipment underwater * Exposure to a pressurised environment and pressure changes ** Pressure changes during descent ** Pressure changes during ascent ** Breathing gases at high ambient pressure * The specific diving environment * Pre-existing physiological and psychological conditions in the diver * Diver behaviour and competence * Failure of diving equipment other than breathing apparatus * Hazards of the dive task and special equipment


Risk assessment

The assessed risk of a dive would generally be considered unacceptable if the diver is not expected to cope with any single reasonably foreseeable incident with a significant probability of occurrence during that dive. Professional diving organisations tend to be less tolerant of risk than recreational, particularly technical divers, who are less constrained by occupational health and safety legislation.


Dive profile

The planned dive profile is an important input parameter for gas planning and decompression planning, and is generally based on the time required to perform the task of each specific dive, and the depth at which the task will be performed, in combination with environmental considerations and the breathing gas mixtures chosen. Limits are often due to exposure to cold, work load, decompression time, safety constraints and logistics of breathing gas supply.


Route

For some dives the route to be followed and navigation procedures to follow the planned route may be important, either for achieving the objective, for safety, or for both. There may be known hazards that can be avoided by following a specific route or constraining the possible extent of diver excursion. In all penetration dives the route may be critical for safety. The diver must be assured of getting out from the overhead zone before running out of gas. The standard method is to follow a
guideline A guideline is a statement by which to determine a course of action. A guideline aims to streamline particular processes according to a set routine or sound practice. Guidelines may be issued by and used by any organization (governmental or pri ...
into and out of the
overhead environment Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment. It is also often referred to as diving, an ambiguous term with several possible meanings, depending on contex ...
, and laying the line or laying and recovering the line may be part of the dive plan. In explorations and surveys the route may be unknown or uncertain, and contingency plans must be known to the divers so that the dive plan can be altered to suit the situation as it unfolds. Professional divers may follow a planned route to the worksite which prevents the diver from close approach to known hazards. This may involve limiting umbilical length and manned or unmanned underwater tending points, downlines and jackstays.


Choice of equipment

Equipment will be chosen based on several constraints, including: *Legal and procedural requirements of the organisation *Availability of equipment *Diver skills and certification *Suitability for the purpose *Risk and benefit considerations Equipment and supplies selection would normally include: * Diving equipment * Breathing gas, including a backup supply * Tools or equipment for the task if appropriate * Dive platform and support equipment, including diver/crew shelter * Oxygen
resuscitator A resuscitator is a device using positive pressure to inflate the lungs of an unconscious person who is not breathing, in order to keep them oxygenated and alive. There are three basic types: a ''manual'' version (also known as a ''bag valve mask ...
and first aid kit * Dive flag * Communications equipment A recreational diver may expect many of these items to be arranged by the service provider (the dive boat operator, shop, or school providing thansport to the dive site and organising the dive).


Decompression planning

Decompression is planned based on the intended dive profile, the chosen gas mixtures, and the chosen
decompression tables There are several categories of decompression equipment used to help divers decompress, which is the process required to allow divers to return to the surface safely after spending time underwater at higher ambient pressures. Decompression o ...
or
algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing c ...
. There are two basic approaches to decompression for surface oriented dives, and one for saturation diving. *Real time computation of tissue gas levels and the appropriate decompression schedule may be monitored by
personal decompression computer A dive computer, personal decompression computer or decompression meter is a device used by an underwater diver to measure the elapsed time and depth during a dive and use this data to calculate and display an ascent profile which according to th ...
s worn by the diver. This system is popular with recreational, technical and scientific scuba divers. Any deviation from the planned profile is automatically taken into account, and the diver can keep track at all times of the current total time required for ascent. The surface team is not aware of the decompression status of a diver unless there is voice communication and the diver reports the information. *Decompression schedules are drawn up for the planned dive profile before the dive from tables or a program. Contingency schedules are usually prepared for scuba divers, which allow for all the reasonably probable deviations from the planned schedule, and usually allow for variations in depth and time. These schedules are carried by the diver and used to manage the ascent profile and decompression. Surface supplied divers are monitored by the surface team, and if they deviate from plan the supervisor can change the schedule to suit. *Saturation diving will decompress the divers only at the end of the diving contract, in the controlled and relatively comfortable environment of the saturation system. The schedule will depend on the pressure and breathing gas mixture, not on the duration of exposure. The procedures chosen will to a large extent depend on the mode of diving and equipment available.


Gas planning

Gas planning for diving operations where divers use open circuit equipment with breathing gas mixtures is more complex than operations where atmospheric air is supplied via low pressure compressor from the surface, or the breathing gas is reclaimed, processed and re-used.


Scuba gas planning

Scuba gas planning is the aspect of dive planning which deals with the calculation or estimation of the amounts and mixtures of gases to be used for a planned
dive profile A dive profile is a description of a diver's pressure exposure over time. It may be as simple as just a depth and time pair, as in: "sixty for twenty," (a bottom time of 20 minutes at a depth of 60 feet) or as complex as a second by second grap ...
, and can be critical to the safety of the dive. The scuba diver by definition is independent of surface supply and, in general, must carry all gas needed for the dive, though in limited circumstances depots of drop cylinders may be placed along the route of the dive for use on the return. This requires the route to be marked and the divers to return along the marked route, and is particularly suited to penetration dives, such as wreck and cave dives. Deep dives with open water ascents can also occasionally make use of surface standby divers who can provide contingency gas to ascending divers whose position is marked by a shotline or decompression buoys. The calculations assume that the dive profile, including decompression, is known, but the process may be iterative, involving changes to the dive profile as a consequence of the gas requirement calculation, or changes to the gas mixtures chosen. Scuba gas planning includes the following aspects: * Choice of
breathing gas A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed h ...
es **to limit decompression requirements **to limit
inert gas narcosis Narcosis while diving (also known as nitrogen narcosis, inert gas narcosis, raptures of the deep, Martini effect) is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gas ...
**to limit
work of breathing Work of breathing (WOB) is the energy expended to inhale and exhale a breathing gas. It is usually expressed as work per unit volume, for example, joules/litre, or as a work rate (power), such as joules/min or equivalent units, as it is not partic ...
* Choice of Scuba configuration * Estimation of gas quantities required for the planned dive, including bottom gas, travel gas, and decompression gases, as appropriate to the profile. * Estimation of gas quantities for reasonably foreseeable contingencies. * Choice of cylinders to carry the required gases. Each cylinder volume and working pressure must be sufficient to contain the required quantity of gas. * Calculation of the pressures for each of the gases in each of the cylinders to provide the required quantities. * Specifying the critical pressures of relevant gas mixtures for appropriate stages (waypoints) of the planned dive profile.


Surface supplied gas planning

Open circuit Open circuit may refer to: *Open-circuit scuba, a type of SCUBA-diving equipment where the user breathes from the set and then exhales to the surroundings without recycling the exhaled air * Open-circuit test, a method used in electrical engineerin ...
surface supplied diving mostly uses air as the breathing gas, though mixed gases may also be used. Surface supplied air is generally supplied by low pressure compressor, and the continuous supply is limited only by the compressor continuing to run effectively, and to provide air of suitable quality. There is also a reserve air supply, either from a second compressor, or from fairly large high pressure cylinders. Each diver also carries a scuba
bailout cylinder A bailout bottle (BoB) or, more formally, bailout cylinder is a scuba cylinder carried by an underwater diver for use as an emergency supply of breathing gas in the event of a primary gas supply failure. A bailout cylinder may be carried by a scu ...
, which should carry sufficient gas to safely surface from any point in the planned dive. Running out of air is a relatively low risk with these facilities, and gas planning centres on ensuring that the primary and, if present, backup compressors are correctly sized to provide the necessary pressure and flow rates. These are specified by the breathing equipment manufacturer based on depth and workload, and by the compressor manufacturer for the standard running speed of the machine. Reserve surface supply cylinder contents are based on the gas requirement for safe ascent from any part of the dive, allowing for reasonably foreseeable delays, and for a rescue by the standby diver. The diver's bailout cylinder should contain adequate gas in case of an emergency at the planned depth. Critical pressure should be calculated based on the planned profile and must allow change-over, ascent and all planned decompression. In some jurisdictions the stand-by diver must be supplied from an air source which is independent of that supplying the working divers, as the cause of an emergency may be failure or contamination of the main air supply to the working diver.


Low pressure compressor delivery

Compressors are rated according to the volume of air taken in each minute. This is also the free gas volume that will be supplied to the divers. The volume of air used by the divers will depend on work rate and depth. Short term variations are compensated by the air receiver on the compressor. The delivery volume at maximum ambient pressure for the planned dive must be sufficient for all the divers to be supplied from the compressor. The supply pressure must be in excess of minimum functional pressure for the regulator to be enough to get air to the diver. In practice a delivery pressure of about 20 bar is commonly used. The manufacturer of the helmet or full-face mask will specify a pressure range which will deliver sufficient air for a given dive depth, which is usually from 6 to 10 bar more than the ambient pressure due to depth.


Free flow helmets

Free flow helmets generally require a considerably higher compressor delivery than demand helmets, as the flow is continuous, and should never drop below peak inhalation rate of the diver. Flow rates up to 1500 litres per minute surface equivalent are quoted for the Divex AH-5 helmet at 50
metres sea water The metre (or meter) sea water (msw) is a metric unit of pressure used in underwater diving. It is defined as one tenth of a bar. The unit used in the US is the foot sea water (fsw), based on standard gravity and a sea-water density of 64  ...
for heavy work. Delivery pressure at the AH-5 helmet is recommended at 3.5 bar above ambient.


Saturation gas planning

Saturation systems frequently use gas reclaim equipment to minimize the loss of expensive
helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...
, and this makes the gas usage relatively independent of dive duration and depth, however reserves must be available in case of loss or leakage. Scrubber systems are used to remove
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
from the breathing gas, and other filters to remove odours and other contaminants.
Booster pump Booster may refer to: Amusement rides * Booster (Fabbri ride), a pendulum ride * Booster (HUSS ride), an evolution of the Breakdance ride * Booster (KMG ride), a pendulum ride Arts, entertainment, and media Fictional characters *Booster, a cha ...
systems are used to return gas to high pressure storage.


Contingency plans

Contingency planning covers what to do if something happenes that is not according to the planned operation. The hazard identification and risk assessment will suggest the range of foreseeable contingencies, and the specifics of how much to organise to deal with them will depend on the consequences. In general, contingencies that have serious health and safety consequences should have plans in place to deal with them, while those which are merely an inconvenience may be accepted if they occur. Some contingency classes are listed here: *Environmental condition changes **Weather and sea state *Equipment malfunctions *Incorrect information **Position of site **Accessibility **Environmental conditions **Unexpected hazards **Extent of work, equipment required One contingency that must always be considered is an out-of-gas emergency, as there are several ways it can happen, it is known to have happened by most of these ways on more than one occasion, and the consequences can be fatal. The diver must be able to safely reach a reliable alternative source of breathing gas at all times during the planned dive. Plans for technical contingencies may include arrangements for alternative equipment, spares, alternative boat etc. The level of contingency planning will depend on the project, and the importance of the task. Plans for adverse conditions may include arrangements for alternative dates, or in some cases alternative venues.


Emergency plans

In general, there should be plans to deal with reasonably foreseeable emergencies that pose a risk to health and safety wherever there is a duty of care, these may include where relevant: *First Aid for medical emergencies *Search and recovery *Casualty evacuation *Site evacuation *
Hazmat Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabi ...
emergencies Some of the action generally taken to prepare for possible medical emergencies will include: *Appropriate first aid equipment available on site *Adequate oxygen administration equipment available on site *A plan for evacuation of a casualty to a hyperbaric chamber *A list of contact numbers, call codes and frequencies for local emergency services. *How to reach the nearest suitable emergency medical facility from the site.


Permits and permission

It may be necessary to arrange for clearance to dive. Permits or permission for access or to dive at the site may be required, and making the arrangements can be considered part of dive planning. This may include, but is not limited to: *Permits to dive in a
marine protected area Marine protected areas (MPA) are protected areas of seas, oceans, estuaries or in the US, the Great Lakes. These marine areas can come in many forms ranging from wildlife refuges to research facilities. MPAs restrict human activity for a conserv ...
*Permits to collect specimens at a specific site or in general. *Permits to use specific collecting methods. *Permits to operate specific equipment. *Permits to dive on an
archaeological site An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology an ...
. *Permits to perform salvage work. *Permits to perform
drilling and blasting Drilling and blasting is the controlled use of explosives and other methods, such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel o ...
work. *Permits or permission to launch or recover a vessel at a specific place. *Permits to operate a vessel in restricted areas. *Permission from harbourmaster to dive within harbour limits. *Permission from port control to dive in shipping lanes. *Permission from landowners to access the water, and to dive in inland waters. *Permission from utilities companies to dive in reservoirs. *Clearance from vessel operators or installation operators that the site is safe to dive. *Clearance that contamination is acceptable for the diving equipment to be used. This may require a water sample to be tested before the dive.


Schedule of operational tasks

* Travel to the site * Preparation of diving and support equipment * Predive briefing * Actual diving operations * Recovery, cleaning, inspection, repair, and storage of gear * Debriefing


Budget

Estimating the
cost In production, research, retail, and accounting, a cost is the value of money that has been used up to produce something or deliver a service, and hence is not available for use anymore. In business, the cost may be one of acquisition, in which ...
of a diving operation is an important component of the planning process, and is dependent on almost all the factors described above.


References

{{Underwater diving, divsaf Underwater work