Terms and Definitions

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Classification Project: Terms and Definitions

Term	Definition(s)
Batteries	All types of batteries used topside (out of water) can also be used undersea. There are a few factors unique to using batteries underwater. One is that some batteries can produce gases that are potentially explosive. In the open air this is usually not a problem because the small volume of off-gases is quickly diluted. However, in sealed pressure housing, gas build-up can cause problems ranging from water leaks to explosive failure. Pressure relief valves can safely vent gas to eliminate these problems. Some batteries and other subsea electronics use pressure-balanced, oil-filled packaging. In this method, all air spaces and voids in a housing are filled with oil or hydraulic fluid. A flexible membrane on the housing transmits ambient water pressure through the housing. Because the pressure inside the housing is the same as the outside water pressure, it is said to be equalized. Since there is no pressure gradient, a heavy pressure-proof housing is not required. ... (more at Batteries)
Bottom Samplers	are sediment sampling devices. There are many different types of bottom samplers. A box corer can be dropped into the mud to bring back a block of nearsurface sediment. A piston corer can return a cylinder of sediment up to 100 feet (33 meters) long that may encompass several million years of sedimentary history. For researchers especially interested in the seawater-seafloor interface, a gravity corer can return cores up to 20 feet (6 meters) long with little core-top disturbance. Vibracorers use a motor that produces a high-frequency oscillatory vibration to help propel a long core barrel into unconsolidated sediments.
Buoys	There are two main classes of buoys: drifting and moored. As the name implies, drifting buoys are not anchored to the seafloor. They are typically used to study currents and circulation patterns. A drogue (a cylindrical or funnel-shaped device) is sometimes added to have the surface buoy follow a subsurface current. ... (more at Buoys)