|
Penetration Diving
An overhead or penetration diving environment is where the diver enters a space from which there is no direct, purely vertical ascent to the safety of breathable atmosphere at the surface. Cave diving, wreck diving, ice diving and diving inside or under other natural or artificial underwater structures or enclosures are examples. The restriction on direct ascent increases the risk of diving under an overhead, and this is usually addressed by adaptations of procedures and use of equipment such as redundant breathing gas sources and guide lines to indicate the route to the exit. There are some applications where scuba diving is appropriate and surface-supplied diving is not, and other where the converse is true. In other applications either may be appropriate, and the mode is chosen to suit the specific circumstances. In all cases risk is managed by appropriate planning, skills, training and choice of equipment. Environments Penetration diving is also known as diving in overhe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cave Diving
Cave-diving is underwater diving in water-filled caves. It may be done as an extreme sport, a way of exploring flooded caves for scientific investigation, or for the underwater search and recovery, search for and recovery of divers or, as in the Tham Luang cave rescue, 2018 Thai cave rescue, other cave users. The equipment used varies depending on the circumstances, and ranges from Free-diving, breath hold to Surface-supplied diving, surface supplied, but almost all cave-diving is done using scuba equipment, often in specialised configurations with engineering redundancy, redundancies such as Sidemount diving, sidemount or backmounted twinset. Recreational cave-diving is generally considered to be a type of technical diving due to the lack of a free surface during large parts of the dive, and often involves planned Decompression (diving), decompression stops. A distinction is made by recreational diver training agencies between cave-diving and cavern-diving, where cavern diving i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cave Diver Running A Reel
Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance underground (such as rock shelters). Caves which extend further underground than the opening is wide are called endogene caves. Speleology is the science of exploration and study of all aspects of caves and the cave environment. Visiting or exploring caves for recreation may be called Caving, ''caving'', ''potholing'', or ''spelunking''. Formation types The formation and development of caves is known as ''speleogenesis''; it can occur over the course of millions of years. Caves can range widely in size, and are formed by various geological processes. These may involve a combination of chemical processes, erosion by water, tectonic forces, microorganisms, pressure, and atmospheric influences. Isotopic dating techniques can be applied to cave sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Equipment
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. The fundamental item of diving equipment used by divers other than freedivers, is underwater breathing apparatus, such as scuba equipment, and surface-supplied diving equipment, but there are other important items of equipment that make diving safer, more convenient or more efficient. Diving equipment used by recreational scuba divers, also known as scuba gear, is mostly personal equipment carried by the diver, but professional divers, particularly when operating in the surface supplied or saturation mode, use a large amount of support equipment not carried by the diver. Equipment which is used for underwater work or other activities which is not directly related to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decompression (diving)
The decompression of a diver is the reduction in ambient pressure experienced during ascent from depth. It is also the process of elimination of dissolved inert gases from the diver's body which accumulate during ascent, largely during pauses in the ascent known as decompression stops, and after surfacing, until the gas concentrations reach equilibrium. Divers breathing gas at ambient pressure need to ascend at a rate determined by their exposure to pressure and the breathing gas in use. A diver who only breathes gas at atmospheric pressure when free-diving or snorkelling will not usually need to decompress. Divers using an atmospheric diving suit do not need to decompress as they are never exposed to high ambient pressure. When a diver descends in the water, the hydrostatic pressure, and therefore the ambient pressure, rises. Because breathing gas is supplied at ambient pressure, some of this gas dissolves into the diver's blood and is transferred by the blood to ot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Surface
In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress, such as the interface between two homogeneous fluids. An example of two such homogeneous fluids would be a body of water (liquid) and the air in the Earth's atmosphere (gas mixture). Unlike liquids, gases cannot form a free surface on their own. Fluidized/ liquified solids, including slurries, granular materials, and powders may form a free surface. A liquid in a gravitational field will form a free surface if unconfined from above. Under mechanical equilibrium this free surface must be perpendicular to the forces acting on the liquid; if not there would be a force along the surface, and the liquid would flow in that direction. Thus, on the surface of the Earth, all free surfaces of liquids are horizontal unless disturbed (except near solids dipping into them, where surface tension distorts the surface in a region called the meniscus). In a free liquid that is not affecte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical Diving
Technical diving (also referred to as tec diving or tech diving) is scuba diving that exceeds the List of diver certification organizations, agency-specified limits of recreational diving for non-Professional diver, professional purposes. Technical diving may expose the diver to hazards beyond those normally associated with recreational diving, and to a greater risk of serious injury or death. Risk may be reduced by using suitable equipment and procedures, which require appropriate knowledge and skills. The required knowledge and skills are preferably developed through specialised training, adequate practice, and experience. The equipment involves breathing gases other than air or standard nitrox mixtures, and multiple gas sources. Most technical diving is done within the limits of training and previous experience, but by its nature, technical diving includes diving which pushes the boundaries of recognised safe practice, and new equipment and procedures are developed and honed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sidemount Diving
Sidemount is a scuba diving equipment configuration which has scuba sets mounted alongside the diver, below the shoulders and along the hips, instead of on the back of the diver. It originated as a configuration for advanced cave diving, as it facilitates penetration of tight sections of cave, allows easy access to cylinder valves, provides easy and reliable gas redundancy, and tanks can be easily removed when necessary. These benefits for operating in confined spaces were also recognized by divers who conducted technical wreck diving penetrations. Sidemount diving is now growing in popularity within the technical diving community for general decompression diving, and is becoming an increasingly popular specialty training for recreational diving 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, amus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Redundancy
In engineering and systems theory, redundancy is the intentional duplication of critical components or functions of a system with the goal of increasing reliability of the system, usually in the form of a backup or fail-safe, or to improve actual system performance, such as in the case of GNSS receivers, or multi-threaded computer processing. In many safety-critical systems, such as fly-by-wire and hydraulic systems in aircraft, some parts of the control system may be triplicated, which is formally termed triple modular redundancy (TMR). An error in one component may then be out-voted by the other two. In a triply redundant system, the system has three sub components, all three of which must fail before the system fails. Since each one rarely fails, and the sub components are designed to preclude common failure modes (which can then be modelled as independent failure), the probability of all three failing is calculated to be extraordinarily small; it is often outweighed by othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scuba Equipment
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 word ''scuba'' is an acronym 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, affording them greater independence and movement than surface-supplied divers, and more time underwater than freedivers. Although the use of compressed air is common, other gas blends are also used. Open-circuit scuba systems discharge the breathing gas into the environment as it is exhaled and consist of one or more diving cylinders containing breathing gas at high pressure which is supplied to the diver at ambient pressure through a diving regulator. They may include additional cylinders for range extension, decompression gas or emergency breathing gas. Closed-cir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface-supplied Diving
Surface-supplied diving is a mode of underwater diving using equipment supplied with breathing gas through 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 scuba diving, where the diver's breathing equipment is completely self-contained and there is no essential link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work. The copper helmeted free-flow standard di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free-diving
Freediving, free-diving, free diving, breath-hold diving, or skin diving, is a mode of underwater diving that relies on apnea, breath-holding until resurfacing rather than the use of breathing apparatus such as scuba set, scuba gear. Besides the limits of Apnea, breath-hold, immersion in water and exposure to high ambient pressure also have physiological effects that limit the depths and duration possible in freediving. Examples of freediving activities are artisanal fishing, traditional fishing techniques, competitive and non-competitive freediving, competitive and non-competitive spearfishing and freediving photography, synchronised swimming, underwater football, underwater rugby, underwater hockey, underwater target shooting and snorkeling. There are also a range of "competitive apnea" disciplines; in which competitors attempt to attain great depths, times, or distances on a single breath. Historically, the term ''free diving'' was also used to refer to scuba diving, due to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tham Luang Cave Rescue
In June/July 2018, a junior association football team became trapped for fifteen days in Tham Luang Nang Non, a cave system in Chiang Rai province, northern Thailand, but were ultimately rescued. Twelve members of the team, aged 11 to 16, and their 25-year-old assistant coach entered the cave on 23 June after a practice session. Shortly after they entered, heavy rainfall began and partially flooded the cave system, blocking their way out and trapping them deep within. Efforts to locate the group were hampered by rising water levels and strong currents, and the team were out of contact with the outside world for more than a week. The cave rescue effort expanded into a massive operation amid intense worldwide public interest and involved international rescue teams. On 2 July, after advancing through narrow passages and muddy waters, British divers John Volanthen and Rick Stanton found the group alive on an elevated rock about from the cave mouth. Rescue organisers d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
