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Deployment Of A Decopression Buoy
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 ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoy
A buoy (; ) is a buoyancy, floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. History The ultimate origin of buoys is unknown, but by 1295 a seaman's manual referred to navigation buoys in the Guadalquivir River in Spain. To the north there are early medieval mentions of the French / Belgian River Meuse, Maas being buoyed. Such early buoys were probably just timber beams or rafts, but in 1358 there is a record of a barrel buoy in the Dutch Maasmond (also known as the Maas Sluis or Maasgat). The simple barrel was difficult to secure to the seabed, and so a conical ''tonne'' was developed. They had a solid plug at the narrow end through which a mooring ring could be attached. By 1790 the older conical tonne was being replaced by a ''nun'' buoy. This had the same conical section below the waterline as the tonne buoy, but at the waterline a barrel shape was used to allow a truncated cone to be above the water. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy Compensator (diving)
Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus, the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. For this reason, an object with average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of the fluid it displaces. If the object is less dense, buo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bolt Snap
A bolt snap is a type of snap hook with a manually operated bolt action slide gate of medium security used to clip a light load to a ring, eye, loop or bight to temporarily secure or suspend an object. They are used for a wide variety of applications including dog leads and for clipping scuba equipment to the diving harness. A similar but more secure device used to attach sails to a stay is known as a piston hank. The most common type has a single snap hook at one end and a swivel ring at the other, but double ended bolt snaps and single ended snaps with a swivel shackle are also available. There are a few variations on the style of the hook, gate opening and swivel style. The characteristic element of the bolt snap is the bolt action gate. This is a spring loaded rod which slides longitudinally inside the body of the clip against a compression spring to open the gate of the hook, and returns to rest against the tip of the hook by the action of the spring when released. Bolt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slate (writing)
A slate is a thin piece of hard flat material, historically slate stone, which is used as a medium for writing on. Writing on a slate is impermanent and easily erased, and the same slate is then reused. Usage The writing slate consisted of a piece of slate, typically either 4x6 inches or 7x10 inches, encased in a wooden frame. Split slate was prepared by scraping with a steel edge, grinding with a flat stone and, finally, polishing with a mix of slate powder in water. Pencils were of a softer stone, such as shale, chalk or soapstone. In 1853 Charles Goodyear patented a compound of hard-vulcanised rubber with powdered porcelain, from which to make white pencils for writing on slates. Usually, a piece of cloth or slate sponge, sometimes attached with a string to the bottom of the writing slate, was used to erase it for reuse. History The exact origins of the writing slate remain unclear. References to its use can be found in the fourteenth century and evidence suggests t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyalume Stick
A glow stick, also known as a light stick, chem light, light wand, light rod, and rave light, is a self-contained, short-term light-source. It consists of a translucent plastic tube containing isolated substances that, when combined, make light through chemiluminescence. The light cannot be turned off and can be used only once. The used tube is then thrown away. Glow sticks are often used for recreation, such as for events, camping, outdoor exploration, and concerts. Glow sticks are also used for light in military and emergency services applications. Industrial uses include marine, transportation, and mining. History Bis(2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl)oxalate, trademarked "Cyalume", was invented in 1971 by Michael M. Rauhut, of American Cyanamid, based on work by Edwin A. Chandross and David Iba Sr. of Bell Labs. Other early work on chemiluminescence was carried out at the same time, by researchers under Herbert Richter at China Lake Naval Weapons Center. Sever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strobe Light
A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning "act of whirling". A typical commercial strobe light has a flash energy in the region of 10 to 150 joules, and discharge times as short as a few milliseconds, often resulting in a flash power of several kilowatts. Larger strobe lights can be used in “continuous” mode, producing extremely intense illumination. The light source is commonly a xenon flash lamp, or ''flashtube'', which has a complex spectrum and a color temperature of approximately 5,600 kelvins. To obtain colored light, colored gels may be used. Scientific explanation of flashtubes Strobe lights usually use flashtubes with energy supplied from a capacitor, an energy storage device much like a battery, but capable of charging and releasing energy much faster. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reel With DSMB P9027417 (cropped)
A reel is a tool used to store elongated and flexible objects (e.g. yarns/ cords, ribbons, cables, hoses, etc.) by wrapping the material around a cylindrical core known as a '' spool''. Many reels also have flanges (known as the ''rims'') around the ends of the spool to help retain the wrapped material and prevent unwanted slippage off the ends. In most cases, the reel spool is hollow in order to pass an axle and allow it to spin like a wheel, a winding process known as ''reeling'', which can be done by manually turning the reel with handles or cranks, or by machine-powered rotating via (typically electric) motors. Construction The size of the core is dependent on several factors. A smaller core will obviously allow more material to be stored in a given space. However, there is a limit to how tightly the stored material can be wound without damaging it and this limits how small the core can be. Other issues affecting the core size include: * Mechanical strength of the core ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lifting Bag
A lifting bag is an item of diving equipment consisting of a robust and air-tight bag with straps, which is used to lift heavy objects underwater by means of the bag's buoyancy. The heavy object can either be moved horizontally underwater by the Underwater diving, diver or sent unaccompanied to the surface. Lift bag appropriate capacity should match the task at hand. If the lift bag is grossly oversized a runaway or otherwise out of control ascent may result. Commercially available lifting bags may incorporate dump valves to allow the operator to control the buoyancy during ascent, but this is a hazardous operation with high risk of entanglement in an uncontrolled lift or sinking. If a single bag is insufficient, multiple bags may be used, and should be distributed to suit the load. There are also lifting bags used on land as short lift jacks for lifting cars or heavy loads or lifting bags which are used in machines as a type of pneumatic actuator which provides load over a large ... [...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 cylinder ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
