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Downline (diving)
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. Arrangement and use There is no definitive arrangement. A downline is a generic piece of support equipment that can be set up using available components and is defined by its function. The top end can be secured to any suitably secure point in an appropriate place. This can be a large float or buoy, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Diving
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 context. Immersion in water and exposure to high ambient pressure have physiological effects that limit the depths and duration possible in ambient pressure diving. Humans are not physiologically and anatomically well-adapted to the environmental conditions of diving, and various equipment has been developed to extend the depth and duration of human dives, and allow different types of work to be done. In ambient pressure diving, the diver is directly exposed to the pressure of the surrounding water. The ambient pressure diver may dive on breath-hold (freediving) or use breathing apparatus for scuba diving or surface-supplied diving, and the saturation diving technique reduces the risk of decompression sickness (DCS) after long-duration deep dives ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Anchor
A sea anchor (also known as a parachute anchor, drift anchor, drift sock, para-anchor or boat brake) is a device that is streamed from a boat in heavy weather. Its purpose is to stabilize the vessel and to limit progress through the water. Rather than tethering the boat to the seabed with a conventional anchor, a sea anchor provides hydrodynamic drag, thereby acting as a brake. Normally attached to a vessel's bows, a sea anchor can prevent the vessel from turning broadside to the waves and being overwhelmed by them. Early sea anchors were crude devices, but today most take the form of a marine drogue parachute. These are so efficient that they need a tripping line to collapse the parachute for retrieval. Being made of fabric, a sea parachute may be bagged and easily stowed when not in use. A similar device to the sea anchor is the much smaller drogue, which is streamed from a vessel's stern in strong winds so as to slow the boat to prevent pitchpoling or broaching in an o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazy Shot
A diving shot line, shot line, or diving shot, a type of downline or descending line (US Navy), is an item of diving equipment consisting of a ballast weight (the shot), 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. A "lazy shot" is a shot which is suspended above the bottom. It may be tethered to the main shot line at a convenient depth. It is used for decompression and frees the main shot line for other divers. The lazy shot's line does not need to be longer than the decompression depth and is often only deep enough for the longer stops. It only needs a weight heavy enough to provide diver buoyancy cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shotline
A diving shot line, shot line, or diving shot, a type of downline or descending line (US Navy), is an item of diving equipment consisting of a ballast weight (the shot), 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. A "lazy shot" is a shot which is suspended above the bottom. It may be tethered to the main shot line at a convenient depth. It is used for decompression and frees the main shot line for other divers. The lazy shot's line does not need to be longer than the decompression depth and is often only deep enough for the longer stops. It only needs a weight heavy enough to provide diver buoyancy co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scuba Diving
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface air supply. The name "scuba", an acronym for "Self-Contained Underwater Breathing Apparatus", was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long and/or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the likelihood and effects of nitrogen narcosis during deeper dives. Open circuit scuba systems discharge the breathing gas into the environment as it is exhaled, and consist of one or more diving cylinders containing breat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anchor
An anchor is a device, normally made of metal , used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ''ancora'', which itself comes from the Greek ἄγκυρα (ankȳra). Anchors can either be temporary or permanent. Permanent anchors are used in the creation of a mooring, and are rarely moved; a specialist service is normally needed to move or maintain them. Vessels carry one or more temporary anchors, which may be of different designs and weights. A sea anchor is a drag device, not in contact with the seabed, used to minimise drift of a vessel relative to the water. A drogue is a drag device used to slow or help steer a vessel running before a storm in a following or overtaking sea, or when crossing a bar in a breaking sea.. Overview Anchors achieve holding power either by "hooking" into the seabed, or mass, or a combination of the two. Permanent moorings use large masses (common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expl0470 - Flickr - NOAA Photo Library
C mathematical operations are a group of functions in the standard library of the C programming language implementing basic mathematical functions. All functions use floating-point numbers in one manner or another. Different C standards provide different, albeit backwards-compatible, sets of functions. Most of these functions are also available in the C++ standard library, though in different headers (the C headers are included as well, but only as a deprecated compatibility feature). Overview of functions Most of the mathematical functions are defined in ( header in C++). The functions that operate on integers, such as abs, labs, div, and ldiv, are instead defined in the header ( header in C++). Any functions that operate on angles use radians as the unit of angle. Not all of these functions are available in the C89 version of the standard. For those that are, the functions accept only type double for the floating-point arguments, leading to expensive type conversions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Divers Ascending At Shotline Labeled
Diver or divers may refer to: *Diving (sport), the sport of performing acrobatics while jumping or falling into water *Practitioner of underwater diving, including: **scuba diving, **freediving, **surface-supplied diving, **saturation diving, and ** atmospheric suit diving People * Diver (surname) *Edward Divers (1837–1912), British chemist *"Diver", nickname of Tom Derrick (1914–1945), Australian Second World War recipient of the Victoria Cross Military *V-1 flying bomb, code named "diver" by the British World War II armed forces **Operation Diver, the British countermeasures against the German V-1 flying bomb campaign *AUM-N-4 Diver, a proposed U.S. Navy torpedo-carrying missile of the late 1940s. * Diver (United States Navy) Arts and entertainment * ''Diver'' (EP), a 2006 EP by A Wilhelm Scream * "Diver" (Nico Touches the Walls song), a 2011 song by Nico Touches the Walls * "Diver" (Kana-Boon song), a 2015 song by Kana-Boon * ''Divers'' (album), a 2015 album by Joanna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decompression Trapeze
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 obligation for a given dive profile must be calculated and monitored to ensure that the risk of decompression sickness is controlled. Some equipment is specifically for these functions, both during planning before the dive and during the dive. Other equipment is used to mark the underwater position of the diver, as a position reference in low visibility or currents, or to assist the diver's ascent and control the depth. Decompression may be shortened ("accelerated") by breathing an oxygen-rich "decompression gas" such as a nitrox blend or pure oxygen. The high partial pressure of oxygen in such decompression mixes produces the effect known as the oxygen window. This decompression gas is often carried by scuba divers in side-slung cylinders. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rope
A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similarly constructed cord, string, and twine. Construction Rope may be constructed of any long, stringy, fibrous material, but generally is constructed of certain natural or synthetic fibres. Synthetic fibre ropes are significantly stronger than their natural fibre counterparts, they have a higher tensile strength, they are more resistant to rotting than ropes created from natural fibres, and they can be made to float on water. But synthetic ropes also possess certain disadvantages, including slipperiness, and some can be damaged more easily by UV light. Common natural fibres for rope are Manila hemp, hemp, linen, cotton, coir, jute, straw, and sisal. Synthetic fibres in use for rope-making include polypropylene, nylon, polyesters (e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catenary
In physics and geometry, a catenary (, ) is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends in a uniform gravitational field. The catenary curve has a U-like shape, superficially similar in appearance to a parabola, which it is not. The curve appears in the design of certain types of arches and as a cross section of the catenoid—the shape assumed by a soap film bounded by two parallel circular rings. The catenary is also called the alysoid, chainette,MathWorld or, particularly in the materials sciences, funicular. Rope statics describes catenaries in a classic statics problem involving a hanging rope. Mathematically, the catenary curve is the graph of the hyperbolic cosine function. The surface of revolution of the catenary curve, the catenoid, is a minimal surface, specifically a minimal surface of revolution. A hanging chain will assume a shape of least potential energy which is a catenary. Galileo Galil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jackstay (diving)
A jackstay is a cable or bar between two points to support and guide a load between those points, or as an anchor to attach something to be constrained along that line. The term is mostly used in a marine context and originated on sailing ships. Note the use of "stay" implies load bearing working rigging. In diving it is also a line to guide the movements of a diver between the endpoints. Nautical applications Jackstays are used in several maritime applications. These include: * Support and guidance for transfer of personnel and materials between vessels at sea (Replenishment at sea), suspended from a traveller block and controlled by lines running in both directions. * Support and guidance for rescue or transport by breeches buoy, * A rope or rod secured along a vessel's spar to attach an edge of a sail or the end of a gaff, * A rope or rod running vertically on the forward side of the mast on which the yard moves. * A stay for racing or cruising vessels used to steady the ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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