Open-water diving

Last updated

In underwater diving, open water is unrestricted water such as a sea, lake, river, or flooded quarry. It is a contradistinction to confined water (usually a swimming pool) where initial skills training takes place. Open water also means the diver has direct vertical access to the surface of the water in contact with the Earth's atmosphere. [1] Open water diving implies that if a problem arises, the diver can directly ascend vertically to the atmosphere to breathe air. Penetration diving—involving entering caves or wrecks, or diving under ice—is therefore not "open water diving". In some contexts the lack of a decompression obligation is considered a necessary condition for classification of a dive as an open water dive, as a decompression obligation is a procedural and safety restriction on immediate ascent to the surface, but this does not affect the classification of the venue as open water.

Contents

Swim-throughs – the recreational diving term for arches and short, clear, tunnels where the natural light can be seen at the far end, and there is enough clearance that it is theoretically possible for the diver to pass through the narrowest point without contact with the sides, bottom or ceiling, are technically an overhead environment, but this is often overlooked by divers as there is no risk of getting lost inside, and the risk of entrapment is generally low.

Divers progress from learning diving skills in confined or benign water such as a swimming pool to practicing skills in open water in which the environment is not restricted to a small, controlled locality and depth, with conditions more typical of a natural body of water which might be used by divers, [2] and the range of hazards and associated risk is significantly expanded. [3] In this context confined water and benign water are special cases of open water, as they comply with the more general condition of unobstructed access to the surface.

Some recreational diver certification agencies use a variation on this term in the title of their entry level certification. Open Water Diver certification implies that the diver is competent to dive in unrestricted water, with various constraints regarding the conditions, and particularly that their competence is limited to diving in open water with free access to the surface. [4] [5]

Open ocean diving

The extreme case of open water is the deep open ocean, where the bottom is at a depth which is irrelevant to the diver as there would be no chance of surviving long enough to reach it. Open oceanic water is often remarkably clear, but this is not always the case. There is no natural visual reference for depth in the open ocean, and depth monitoring is critically important to diver safety.

Blue-water diving

Tethered diver in blue water dive observing fauna in the water column Expl1969 - Flickr - NOAA Photo Library.jpg
Tethered diver in blue water dive observing fauna in the water column
Marine scientist coordinates a blue water dive for 4 companions - each at the end of a rope tether and each rope kept taut by a weight and pulley system Expl0470 - Flickr - NOAA Photo Library.jpg
Marine scientist coordinates a blue water dive for 4 companions - each at the end of a rope tether and each rope kept taut by a weight and pulley system

Blue-water diving is done in mid-water where the bottom is out of sight of the diver and there may be no fixed visual reference. It is used by scientific divers for direct observation and sampling of pelagic organisms and particulate matter, particularly the gelatinous zoo-plankton that are fragile and transparent, making them relatively inaccessible by other methods, [6] and by recreational divers for observation and photography of a range of organisms not easily seen in inshore waters.

The techniques of blue-water diving have been developed over the years to suit the conditions and address the hazards of an environment which is functionally bottomless, and has no fixed visible positional references. The diver who is focused on small organisms or instruments at close range is likely to have diminished awareness of depth, buoyancy, current, surge, other divers, large organisms, and even the direction to the surface. [6]

An accepted procedure for scientific blue-water collection diving with several working divers, is to tether the working divers to a central hub connected to a surface platform, and to have an in-water safety diver attend the hub. The tethers pass through fairleads at the hub and are tensioned by a weight at the end, which keeps slack out of the line and thereby reduces the risk of entanglement, and prevents the end of the line from passing through the fairlead. The tether serves to limit the distance a diver can move away from the hub, which is typically fastened to a substantial downline supported by a large buoy at the surface, and kept vertical by a weight. The float at the surface allows the divers to move freely in the water column within the constraint of the tether, and drift with the current. The tethers also allow rope signals between the safety diver and the working divers. The surface platform, generally a small boat, may be tethered to the buoy, and if there is sufficient wind to make this a problem a parachute sea anchor can be deployed to minimise drift. Windage will generally position the buoy and boat downwind of the parachute. The other end of the tether is clipped to the diver's harness or buoyancy compensator by some form of quick-release shackle. [6] These procedures and equipment can also be used at night.

If a sea anchor is deployed to limit drift, it must be kept clear of the divers to minimise the risk of entanglement, and it should be buoyed to prevent sinking in a calm. The sea anchor cable should be buoyant line for the same reason. Blue-water diving operations are constrained by water and weather conditions, including wind, sea state, current strength, visibility, and the presence of aggressive predators. [6]

Black-water diving and blackwater photography

Black-water diving is mid-water diving at night, particularly on a moonless night. The environment is referred to as black-water . [7] [8] The term black-water may also be used to refer to diving in zero visibility, or in sewage. Christopher Newbert, author of Within a Rainbow Sea, (1984) is credited as an early black-water diver. [9] In his book, he describes solo offshore night dives to depths of up to 150 feet (46 m). [10] Black-water diving is often done as a photographic opportunity for recreational divers as there can be a wide range of plankton that would not often be seen by day or closer inshore. [11] This is known as blackwater photography. [12]

Weighted downlines are commonly used to provide a stable vertical reference. These may be tied to the boat or supported by a buoy. Each diver may be attached to a downline using a shorter tether to ensure that divers do not go too far from the boat or too deep. [11] The downline may be marked with lights to indicate depth and to attract mobile organisms. [10] A wide range of animal life may be seen, including many species that spend the daylight hours at depths below those accessible to ambient pressure divers, and migrate vertically through the water column on a diurnal cycle. [9] Many of these are bioluminescent or translucent or both. [10]

The boat moves differently from the divers and the divers move differently from the plankton, making it necessary to work to get a position from which there will be enough time to frame and take photos of the drifting subjects. The boat will drift under the influence of current and wind, while the divers and plankton will drift with the current. If there is wind the boat will drag the downlines, and if tethered to the buoy, it will drag the buoy and divers attached. If divers swim ahead of the towing action, they will have a short time to drift with the plankton and take photos until the slack in the line has been taken up, at which point the plankton will be left behind. [11] This drift problem can be reduced by setting a parachute anchor, which will reduce wind drift to a negligible amount. The divers should stay clear of the entanglement hazard of the parachute suspension lines. [7]

Related Research Articles

<span class="mw-page-title-main">Drift diving</span> Scuba diving where the diver is intentionally transported by the water flow

Drift diving is a type of scuba diving where the diver is transported by the water movement caused by the tide, an ocean current or in a river. The choice whether to drift dive depends on the purpose of the dive, and whether there is an option. At some sites there is almost always a current running, and at others the strength and direction of water movement may vary with the tide, or other driving forces, like wind or recent rainfall. At some sites there may be considerable variation in visibility and underwater life activity based on the speed and direction of flow.

<span class="mw-page-title-main">Night diving</span> Underwater diving during the hours of darkness

Night diving is underwater diving done during the hours of darkness. It frequently refers specifically to recreational diving which takes place in darkness. The diver can experience a different underwater environment at night, because many marine animals are nocturnal.

<span class="mw-page-title-main">Surface marker buoy</span> Buoy towed by a scuba diver to indicate the divers position

A surface marker buoy, SMB, dive float or simply a blob is a buoy used by scuba divers, at the end of a line from the diver, intended to indicate the diver's position to people at the surface while the diver is underwater. Two kinds are used; one (SMB) is towed for the whole dive, and indicates the position of the dive group throughout the dive, and the other, a delayed surface marker buoy, DSMB or decompression buoy, is deployed towards the end of the dive as a signal to the surface that the divers have started to ascend, and where they are going to surface. Both types can also function as a depth reference for controlling speed of ascent and accurately maintaining depth at decompression stops. Surface marker buoys are also used by freedivers in open water, to indicate the approximate position of the diver when submerged. They may also be used to support a catch bag or fish stringer by underwater hunters and collectors. A DSMB is considered by recreational scuba divers and service providers to be a highly important item of safety equipment, yet its use is not part of the entry level recreational diver training for all training agencies, and there are significant hazards associated with incompetent use.

<span class="mw-page-title-main">Diver communications</span> Methods used by underwater divers to communicate

Diver communications are the methods used by divers to communicate with each other or with surface members of the dive team. In professional diving, diver communication is usually between a single working diver and the diving supervisor at the surface control point. This is considered important both for managing the diving work, and as a safety measure for monitoring the condition of the diver. The traditional method of communication was by line signals, but this has been superseded by voice communication, and line signals are now used in emergencies when voice communications have failed. Surface supplied divers often carry a closed circuit video camera on the helmet which allows the surface team to see what the diver is doing and to be involved in inspection tasks. This can also be used to transmit hand signals to the surface if voice communications fails. Underwater slates may be used to write text messages which can be shown to other divers, and there are some dive computers which allow a limited number of pre-programmed text messages to be sent through-water to other divers or surface personnel with compatible equipment.

<span class="mw-page-title-main">Diving shot</span> Substantial weighted near-vertical line with buoy

A diving shot line, shot line, or diving shot, a type of downline or descending line, is an item of diving equipment consisting of a ballast weight, a line and a buoy. The weight is dropped on the dive site. The line connects the weight and the buoy and is used by divers to as a visual and tactile reference to move between the surface and the dive site more safely and more easily, and as a controlled position for in-water staged decompression stops. It may also be used to physically control rate of descent and ascent, particularly by surface-supplied divers.

<span class="mw-page-title-main">Dive boat</span> Boat used for the support of scuba diving operations

A dive boat is a boat that recreational divers or professional scuba divers use to reach a dive site which they could not conveniently reach by swimming from the shore. Dive boats may be propelled by wind or muscle power, but are usually powered by internal combustion engines. Some features, like convenient access from the water, are common to all dive boats, while others depend on the specific application or region where they are used. The vessel may be extensively modified to make it fit for purpose, or may be used without much adaptation if it is already usable.

<span class="mw-page-title-main">Diver rescue</span> Rescue of a distressed or incapacitated diver

Diver rescue, usually following an accident, is the process of avoiding or limiting further exposure to diving hazards and bringing a diver to a place of safety. A safe place generally means a place where the diver cannot drown, such as a boat or dry land, where first aid can be administered and from which professional medical treatment can be sought. In the context of surface supplied diving, the place of safety for a diver with a decompression obligation is often the diving bell.

<span class="mw-page-title-main">Canoe and kayak diving</span> Recreational diving from a canoe or kayak

Canoe diving and Kayak diving are recreational diving where the divers paddle to a diving site in a canoe or kayak carrying all their gear in or on the boat to the place they want to dive. Canoe or kayak diving gives the diver independence from dive boat operators, while allowing dives at sites which are too far to comfortably swim, but are sufficiently sheltered.

<span class="mw-page-title-main">Diving equipment</span> Equipment used to facilitate underwater diving

Diving equipment, or underwater diving equipment, is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found to be suitable for diving use.

<span class="mw-page-title-main">Ascending and descending (diving)</span> Procedures for safe ascent and descent in underwater diving

In underwater diving, ascending and descending is done using strict protocols to avoid problems caused by the changes in ambient pressure and the hazards of obstacles near the surface such as collision with vessels. Diver certification and accreditation organisations place importance on these protocols early in their diver training programmes. Ascent and descent are historically the times when divers are injured most often when failing to follow appropriate procedure.

<span class="mw-page-title-main">Dive planning</span> The process of planning an underwater diving operation

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.

<span class="mw-page-title-main">Scuba skills</span> The skills required to dive safely using a self-contained underwater breathing apparatus.

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.

<span class="mw-page-title-main">Decompression equipment</span> Equipment used by divers to facilitate decompression

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.

<span class="mw-page-title-main">Outline of underwater diving</span> Hierarchical outline list of articles related to underwater diving

The following outline is provided as an overview of and topical guide to underwater diving:

<span class="mw-page-title-main">Index of underwater diving</span> Alphabetical listing of underwater diving related topics

The following index is provided as an overview of and topical guide to underwater diving:

Diving support equipment is the equipment used to facilitate a diving operation. It is either not taken into the water during the dive, such as the gas panel and compressor, or is not integral to the actual diving, being there to make the dive easier or safer, such as a surface decompression chamber. Some equipment, like a diving stage, is not easily categorised as diving or support equipment, and may be considered as either.

In underwater diving, a downline is a piece of substantial cordage running from a point at the surface to the underwater workplace, and kept under some tension. It can be used as a guideline for divers descending or ascending, for depth control in blue-water diving, and as a guide for transfer of tools and equipment between surface and diver by sliding them along the downline at the end of a messenger line. A shotline is a special case of downline which uses a heavy weight at the bottom and a float at the top. A jackstay is a more lateral equivalent, that commonly follows a surface, and will not usually allow materials transfer without a messenger line from the destination end.

Low impact diving is recreational scuba diving that is intended to minimise environmental impact by using techniques and procedures that reduce the adverse effects on the environment to the minimum that is reasonably practicable for the situation. To a large extent this is achieved by avoiding contact with sensitive reef life, but it also applies to diving on historical wrecks and in caves with delicate rock formations. It is in the interests of diving tourism service providers to help protect the condition of the dive sites on which their businesses rely. They can contribute by encouraging and teaching low impact diving and following best-practice procedures for diving in sensitive areas. Low impact diving training has been shown to be effective in reducing diver contact with the bottom, the most common cause of reef damage.

References

  1. ↑ "Section 2". Australian Standard AS2815.3-1992, Training and certification of occupational divers, Part 3: Air diving to 50m (2nd ed.). Homebush, NSW 2140: Standards Australia. 1992. p. 9. ISBN   0 7262 7631 6.{{cite book}}: CS1 maint: location (link)
  2. ↑ "General Standards and Procedures Guide". PADI Instructor Manual (Rev. 1/10 ed.). Professional Association of Diving Instructors. 2010. p. 17.
  3. ↑ Class IV Training Standard (Revision 5 ed.). South African Department of Labour. October 2007.
  4. ↑ "Open Water Diver". Professional Association of Diving Instructors. Archived from the original on 1 October 2018. Retrieved 4 October 2013.
  5. ↑ "Open Water Diver & Scuba Diver". Scuba Schools International. Archived from the original on 4 October 2013. Retrieved 4 October 2013.
  6. 1 2 3 4 Haddock, Stephen H. D.; Heine, John N. (2005). Scientific Blue-Water Diving (PDF). California Sea Grant College Program. Archived from the original (PDF) on 25 March 2016. Retrieved 23 November 2018.
  7. 1 2 Bartick, Mike (Spring 2017). "Blackwater Diving". Alert Diver. Divers Alert Network. Archived from the original on 7 November 2019. Retrieved 7 November 2019.
  8. ↑ "All you'll ever need to know about Blackwater Diving!". info@indigoscuba.com. Archived from the original on 7 November 2019. Retrieved 7 November 2019.
  9. 1 2 Hurley, Becca (6 November 2018). "Battle of the Blackwater Guides". Archived from the original on 3 January 2021. Retrieved 7 November 2019.
  10. 1 2 3 Hayward, Tom (5 August 2015). "Florida's Black Water Diving". xray-mag.com. Archived from the original on 7 November 2019. Retrieved 7 October 2019.
  11. 1 2 3 Milisen, Jeffrey. "Photo Tips for Blackwater Diving". Archived from the original on 7 November 2019. Retrieved 7 November 2019.
  12. ↑ Olsen, Erik (30 March 2021). "The Ocean's Youngest Monsters Are Ready for Glamour Shots". The New York Times . Archived from the original on 3 April 2021. Retrieved 3 April 2021.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.