Those radionavigation systems providing positioning capability beyond the range of short range systems, but their use is generally limited to ranges permitting reliable positioning for about 1 day prior to making landfall; Decca is an example.
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ALUM
Is an aluminum sulfate or filter alum. Acts in the range of 5.0 to 8.0 pH.
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ISO SOLID CONTAMINANT CODE (ISO 4406)
A code assigned on the basis of the number of particles per unit volume greater than 5 and 15 micrometers in size. Range numbers identify each increment in the particle population throughout the spectrum of levels.
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GYRO
Short for GYROSCOPE
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HARMFUL INTERFERENCE
Any emission, radiation or induction which endangers the functioning of a radionavigation service or of other safety services or seriously degrades, obstructs or repeatedly inter- rupts a radio-communication service operating in accordance with the International Telecommunications Union Regulations.
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HYDROLANT
A radio message disseminated by the National Imagery and Mapping Agency and restricted to important marine incidents or navigational changes which affect navigational safety. The HYDROLANT broadcast covers those water areas outside and eastward of NAVAREA IV in the Atlantic Ocean. HYDROLANTS constitute part of the U.S. long range radio navigational warning system. The text of HYDROLANTS issued during a week which are in effect are available through NAVINFONET and are printed in the weekly Notice to Mariners.
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HYPERBOLIC NAVIGATION
Radionavigation based on the measurement of the time differences in the reception of signals from several pairs of synchronized transmitters. For each pair of transmitters the isochrones are substantially hyperbolic. The combination of isochrones for two or more pairs of transmitters forms a hyperbolic lattice within which position can be determined according to the measured time differences
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HYDROPAC
A radio message disseminated by the National Imagery and mapping Agency and restricted to important marine incidents or navigational changes which affect navigational safety. The HYDROPAC broadcast covers those water areas outside of NAVAREA XII in the Pacific Ocean. HYDROPACS constitute part of the U.S. long range radio navigational warning system. The text of HYDROPACS issued during a week which is in effect are available through NAVINFONET and are printed in the weekly Notice to Mariners.
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MULTIGRADE OIL
An oil meeting the requirements of more than one SAE viscosity grade classification, and may therefore be suitable for use over a wider temperature range than a single-grade oil.
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ANNULAR BEARING
Usually a rolling bearing of short cylindrical form supporting a shaft carrying a radial load.
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VISCOSITY INDEX IMPROVER
Additive that increase the viscosity of the fluid throughout its useful temperature range. Such additives are polymers that possess thickening power as a result of their high molecular weight and are necessary for formulation of multi-grade engine oils.
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